Khan Academy Behavioral Sciences Review PDF

MCAT2015 BEHAVIORAL SCIENCES REVIEW Table of Contents NOTE: “x” before the topic means it refers to notes elsewhere Visual Cues........................................................................................................................................................... 8 Sensory Adaptation.......................................................................................................................................... 10 Weber’s Law...................................................................................................................................................... 10 Absolute Threshold of Sensation................................................................................................................... 11 Somatosensation.............................................................................................................................................. 11 The Vestibular System..................................................................................................................................... 12 Signal Detection Theory – Part 1.................................................................................................................... 13 Signal Detection Theory – Part 2.................................................................................................................... 14 Bottom-Up vs. Top-Down Processing............................................................................................................ 15 Gestalt Principles.............................................................................................................................................. 15 Structure of the Eye.......................................................................................................................................... 17 Visual Sensory Information............................................................................................................................. 19 The Phototransduction Cascade..................................................................................................................... 21 Photoreceptors (Rods and Cones)................................................................................................................. 23 Photoreceptor Distribution in Retina............................................................................................................ 24 Visual Field Processing..................................................................................................................................... 25 Feature Detection and Parallel Processing................................................................................................... 26 Auditory Structure – Part 1............................................................................................................................. 27 Auditory Structure – Part 2............................................................................................................................. 29 Auditory Processing.......................................................................................................................................... 30 xSomatosensation............................................................................................................................................ 31 Sensory Adaptation and Amplification......................................................................................................... 32 Somatosensory Homunculus.......................................................................................................................... 32 Proprioception and Kinaesthesia................................................................................................................... 32 Pain and Temperature..................................................................................................................................... 33 Pheromones....................................................................................................................................................... 33 Olfaction – Structure and Function................................................................................................................ 34 Gustation – Structure and Function............................................................................................................... 35 States of Consciousness................................................................................................................................... 38 Sleep Stages and Circadian Rhythms............................................................................................................. 38 Dreaming............................................................................................................................................................ 40 Dream Theories – Freud and Activation Synthesis Hypothesis................................................................. 41 Sleep Disorders................................................................................................................................................. 41 xBreathing-Related Sleep Disorders.............................................................................................................. 42 Hypnosis and Meditation................................................................................................................................ 42 Overview of Psychoactive Drugs.................................................................................................................... 43 Psychoactive Drugs: Depressants and Opiates............................................................................................ 45 Psychoactive Drugs: Stimulants..................................................................................................................... 46 Psychoactive Drugs: Hallucinogens................................................................................................................ 47 Drug Dependence and Homeostasis.............................................................................................................. 47 Routes of Drug Entry........................................................................................................................................ 48 Reward Pathway in the Brain......................................................................................................................... 49 Tolerance and Withdrawal.............................................................................................................................. 50 1 Substance Use Disorders................................................................................................................................. 50 Treatments and Triggers for Drug Dependence.......................................................................................... 52 Divided Attention, Selective Attention, In-attentional Blindness, and Change Blindness................... 54 Theories of Selective Attention...................................................................................................................... 56 The Spotlight Model of Attention and Multitasking................................................................................... 58 Information Processing Model: Sensory, Working, and Long-term Memory......................................... 59 Encoding Strategies.......................................................................................................................................... 63 Retrieval Cues.................................................................................................................................................... 64 Retrieval Cues: Free Recall, Cued Recall, and Recognition........................................................................ 65 Memory Reconstruction, Source Monitoring, and Emotional Memories............................................... 66 Decay and Interference................................................................................................................................... 67 Aging and Cognitive Abilities.......................................................................................................................... 68 Alzheimer’s Disease and Korsakoff syndrome............................................................................................. 69 Semantic Networks and Spreading Activation.................................................................................... 71 Piaget’s Stages of Cognitive Development............................................................................................ 72 Schemas, Assimilation and Accommodation....................................................................................... 75 Problem Solving............................................................................................................................................. 76 Decision Making............................................................................................................................................ 77 Semantic Networks and Spreading Activation.................................................................................... 79 Intelligence...................................................................................................................................................... 79 Theories of Intelligence.............................................................................................................................. 81 Aging and Cognitive Abilities.................................................................................................................... 83 Language and the Brain: Aphasia and Split-Brain Patients............................................................ 83 Theories of Language and Cognition...................................................................................................... 86 Theories of Language Development: Nativist, Learning, Interactionist..................................... 88 Language Components (not a video)/Other language...................................................................... 89 Emotions: Limbic System............................................................................................................................ 90 Emotions: Cerebral Hemispheres and Prefrontal Cortex................................................................ 91 Autonomic Nervous System (ANS) and Physiological Markers of Emotion............................... 92 Three Components of Emotion and the Universal Emotions......................................................... 93 Theories of Emotion..................................................................................................................................... 94 What is Stress?............................................................................................................................................... 98 Stressors........................................................................................................................................................... 99 Responding to Stress.................................................................................................................................... 99 Physical Effects of Stress.......................................................................................................................... 100 Behavioural Effects of Stress.................................................................................................................. 101 Stress Management.................................................................................................................................... 102 Types of Maladaptive Coping Mechanisms:....................................................................................... 104 Structure of the Nervous System........................................................................................................... 105 Functions of the Nervous System.......................................................................................................... 106 Motor Unit..................................................................................................................................................... 106 Peripheral Somatosensation.................................................................................................................. 106 Muscle Stretch Reflex................................................................................................................................ 108 ANS (No Conscious Involvement).......................................................................................................... 108 Gray and White Matter............................................................................................................................. 109 Upper Motor Neurons............................................................................................................................... 109 Somatosensory Tracts.............................................................................................................................. 109 Overview of the Functions of the Cerebral Cortex.......................................................................... 110 2 Hemisphere Differences and Hemisphere Dominance................................................................. 111 The Old Brain............................................................................................................................................... 112 Cerebellum................................................................................................................................................... 112 Brainstem..................................................................................................................................................... 112 Subcortical Cerebrum............................................................................................................................... 114 Neurotransmitter Anatomy.................................................................................................................... 115 Types of Neurotransmitters:.................................................................................................................. 116 Early Methods of Studying the Brain................................................................................................... 118 Lesion Studies and Experimental Ablation....................................................................................... 119 Modern Ways of Studying the Brain.................................................................................................... 120 Endocrine System and Influence on Behaviour – Parts 1 & 2..................................................... 121 Egg, Sperm, Fertilization:......................................................................................................................... 123 Implantation................................................................................................................................................ 124 Germ Layer Derivatives........................................................................................................................... 124 Gestation....................................................................................................................................................... 124 Major Motor Milestones........................................................................................................................... 125 Motor Development................................................................................................................................... 125 Neonatal Reflexes....................................................................................................................................... 126 Physical Development in Adolescence................................................................................................ 126 Brain Changes During Adolescence..................................................................................................... 127 Temperament, Heredity, and Genes.................................................................................................... 128 Twin Studies and Adoption Studies..................................................................................................... 129 Heritability................................................................................................................................................... 132 Regulatory Genes....................................................................................................................................... 133 Gene Environment Interaction.............................................................................................................. 134 Adaptive Value of Behavioral Traits.................................................................................................... 135 Physiological Concept of Positive and Negative Feedback........................................................... 136 Instincts, Arousal, Needs, Drives: Drive-Reduction and Cognitive Theories......................... 136 Maslow’s Hierarchy of Needs................................................................................................................. 138 Incentive Theory........................................................................................................................................ 139 Biological and Sociocultural Factors – Food, Sex, and Drugs...................................................... 139 Components of Attitude........................................................................................................................... 141 Attitudes Influence Behavior................................................................................................................. 142 Behavior Influences Attitude................................................................................................................. 144 Cognitive Dissonance Theory................................................................................................................. 144 Situational Approach................................................................................................................................ 145 xSituational Approach.............................................................................................................................. 147 Psychoanalytic Theory............................................................................................................................. 147 xMaslow’s Hierarchy of Needs............................................................................................................... 148 Humanistic Theory.................................................................................................................................... 148 Biological Theory....................................................................................................................................... 150 Behaviourist Theory................................................................................................................................. 151 Trait Theory................................................................................................................................................. 151 Observational Learning: Bobo Doll Experiment and Social Cognitive Theory...................... 152 Defense Mechanisms................................................................................................................................. 153 Freud – Death Drive, Reality Principle, and Pleasure Principle................................................. 155 Mental Disorders........................................................................................................................................ 155 Categories of Mental Disorders............................................................................................................. 156 Schizophrenia.............................................................................................................................................. 159 3 Biological Basis of Schizophrenia......................................................................................................... 160 Biological Basis of Depression............................................................................................................... 163 Anxiety Disorders and Obsessive Compulsive Disorder............................................................... 164 Dissociate Identity Disorder................................................................................................................... 166 Somatic Symptom Disorders and Other Disorders......................................................................... 167 Personality Disorders............................................................................................................................... 168 xSleep Disorders......................................................................................................................................... 169 Sleep Wake Disorders Breathing Related Sleep Disorders / Breathing Related Sleep Disorders....................................................................................................................................................... 169 xReward Pathway in the Brain.............................................................................................................. 170 xDrug Dependence and Homeostasis.................................................................................................. 170 xTolerance and Withdrawal................................................................................................................... 170 xSubstance Use Disorder......................................................................................................................... 170 Biological Basis of Alzheimer’s disease.............................................................................................. 170 Biological Basis of Parkinson’s Disease.............................................................................................. 171 Depression and Major Depressive Disorder..................................................................................... 172 Depression and Bipolar Disorder......................................................................................................... 174 Conformity and Groupthink................................................................................................................... 175 Conformity and Obedience..................................................................................................................... 176 Asch Conformity Studies (Asch Line Studies)................................................................................... 179 Events That Inspired the Milgram Studies on Obedience............................................................. 180 Milgram Experiment on Obedience..................................................................................................... 181 What Can We Learn from Milgram Experiment?............................................................................. 183 Zimbardo Prison Study – the Stanford Prison Experiment.......................................................... 184 Closer Look at the Stanford Prison Experiment.............................................................................. 185 Factors that Influence Conformity and Obedience......................................................................... 186 Bystander Effect.......................................................................................................................................... 188 Social Facilitation and Social Loafing.................................................................................................. 189 Agents of Socialization.............................................................................................................................. 190 What is Normal? Exploring Folkways, Mores, and Taboos.......................................................... 191 Perspectives on Deviance: Differential Association, Labelling Theory, and Strain Theory.......................................................................................................................................................................... 192 Aspects of Collective Behavior: Fads, Mass Hysteria, and Riots................................................. 194 Types of Learning....................................................................................................................................... 196 Classical Conditioning: Neutral, Conditioned, and Unconditioned Stimuli and Responses.......................................................................................................................................................................... 196 Classical Conditioning: Extinction, Spontaneous Recovery, Generalization, Discrimination.......................................................................................................................................................................... 197 Operant Conditioning: Positive and Negative Reinforcement and Punishment................... 199 Operant Conditioning: Shaping............................................................................................................. 200 Operant Conditioning: Schedules of Reinforcement...................................................................... 201 Operant Conditioning: Innate vs. Learned Behaviours................................................................. 202 Operant Conditioning: Escape and Avoidance Learning............................................................... 203 xObservational Learning: Bobo Doll Experiment and Social Cognitive Theory.................... 203 xLong Term Potentiation and Synaptic Plasticity........................................................................... 203 Non Associative Learning........................................................................................................................ 203 Biological Constraints on Learning...................................................................................................... 204 xComponents of Attitude......................................................................................................................... 206 xAttitude Influences Behavior............................................................................................................... 206 4 xBehavior Influences Attitude............................................................................................................... 206 Persuasion, Attitude Change, and the Elaboration Likelihood Model...................................... 206 Reciprocal Determinism.......................................................................................................................... 207 Personal Control (Locus of Control, Learned Helplessness, and the Tyranny of Choice).. 208 Self-Control................................................................................................................................................... 209 Self Concept, Self Identity, and Social Identity................................................................................. 211 Self-Esteem, Self-Efficacy, and Locus of Control............................................................................... 212 Overview of Theories of Development............................................................................................... 213 Freud’s Psychosexual Development.................................................................................................... 214 Erikson’s Psychosocial Development - (Note the acronyms are from psychfiles and are a stretch).......................................................................................................................................................... 216 Vygotsky Sociocultural Development................................................................................................. 218 Kohlberg Moral Development................................................................................................................ 219 Social Influences [Branch of Social psychology].............................................................................. 221 George Herbert Mead: The I and the Me............................................................................................. 223 Charles Cooley – Looking Glass Self..................................................................................................... 225 Attribution Theory – Basic Co-variation............................................................................................ 226 Attribution Theory – Attribution Error and Culture...................................................................... 227 Stereotypes: Stereotype Threat and Self-fulfilling Prophecies.................................................. 228 Emotion and Cognition in Prejudice.................................................................................................... 229 Prejudice and Discrimination Based on Race, Ethnicity, Power, Social Class, and Prestige.......................................................................................................................................................................... 230 Stigma – Social and Self............................................................................................................................ 231 Social Perception – Primacy and Recency Bias................................................................................ 233 Social Perception – The Halo Effect...................................................................................................... 234 Social Perception – The Just World Hypothesis............................................................................... 235 xSelf Esteem, Self Efficacy, and Locus of Control............................................................................. 237 xSelf Concept, Self Identity, and Social Identity............................................................................... 237 xSocial Influences....................................................................................................................................... 237 xLocus of Control, Learned Helplessness, and the Tyranny of Choice..................................... 237 Proximity and the Mere Exposure Effect............................................................................................ 238 Physical Attraction.................................................................................................................................... 239 Similarity....................................................................................................................................................... 239 Harlow Monkey Experiments................................................................................................................. 240 Secure and Insecure Attachment.......................................................................................................... 241 Aggression.................................................................................................................................................... 242 Altruism......................................................................................................................................................... 244 Social Support.............................................................................................................................................. 244 Status.............................................................................................................................................................. 245 Role Strain and Role Conflict.................................................................................................................. 246 Primary and Secondary Groups............................................................................................................ 247 xEthnocentrism and Cultural Relativism – In Group and Out Group........................................ 247 Dramaturgical Approach......................................................................................................................... 247 Impression Management......................................................................................................................... 248 xAggression.................................................................................................................................................. 249 xHarlow Monkey Experiments.............................................................................................................. 249 xAltruism...................................................................................................................................................... 249 Discrimination – Individual vs. Institutional.................................................................................... 249 Prejudice vs. Discrimination.................................................................................................................. 250 5 Organizations and Bureaucratization................................................................................................. 250 Characteristics of an Ideal Bureaucracy............................................................................................. 251 xSocial Support........................................................................................................................................... 252 xCharles Cooley – Looking Class self.................................................................................................... 252 x George Herbert Mead – The I and the Me........................................................................................ 252 xThree Components of Emotion and Universal Emotions............................................................ 252 Animal Behavior: Foraging..................................................................................................................... 252 Animal Communication............................................................................................................................ 253 Types of Animal Communication.......................................................................................................... 253 Mating Behavior and Inclusive Fitness............................................................................................... 254 Evolutionary Game Theory..................................................................................................................... 255 xDiscrimination -- Individual vs institutional.................................................................................. 256 xPrejudice and discrimination Based on Race, Ethnicity, Power, Social Class, and Prestige.......................................................................................................................................................................... 256 xStereotypes, Stereotype Threat, and Self-Fulfilling Prophecy.................................................. 256 Macrosociology vs. Microsociology...................................................................................................... 257 Social Institutions...................................................................................................................................... 257 Social Institutions – ex. Education, Family, Religion...................................................................... 258 Social Institutions – Government, Economy, Health and Medicine........................................... 259 Functionalism.............................................................................................................................................. 261 Conflict Theory............................................................................................................................................ 262 Social Constructionism............................................................................................................................. 263 Symbolic Interactionism.......................................................................................................................... 264 Feminist Theory.......................................................................................................................................... 265 Rational Choice Theory and Exchange Theory................................................................................. 266 Social Theories Overview (Part 1)....................................................................................................... 268 Social Theories Overview (Part 2)....................................................................................................... 268 Relating Social Theories to Medicine.................................................................................................. 269 Demographic Structure of Society – Age............................................................................................ 270 Demographic Structure of Society – Race and Ethnicity............................................................... 272 Demographic Structure of Society – Immigration........................................................................... 274 Demographic Structure of Society – Sex, Gender, and Sexual Orientation............................. 275 Demographic Structure of Society Overview [Lots of repeat to above but a new KA video].......................................................................................................................................................................... 278 Urbanization................................................................................................................................................ 280 Population Dynamics................................................................................................................................ 282 Demographic Transition (some material included above under growth rate).................... 284 Globalization Theories............................................................................................................................. 287 Globalization – Trade and Transnational Corporations............................................................... 289 Social Movements....................................................................................................................................... 290 Overview of Demographics..................................................................................................................... 292 Culture and Society.................................................................................................................................... 295 Overview of Culture................................................................................................................................... 295 Subculture vs. Counterculture............................................................................................................... 296 Jim Goes to College Subculture.............................................................................................................. 297 Culture Lag and Culture Shock............................................................................................................... 297 Diffusion........................................................................................................................................................ 298 Mass Media................................................................................................................................................... 298 Evolution and Human Culture............................................................................................................... 300 6 Overview of Social Inequality................................................................................................................ 302 Upward and Downward Mobility,......................................................................................................... 302 Inter-Generational and Intra-Generational Mobility, Social Mobility...................................... 303 Absolute and Relative Poverty.............................................................................................................. 303 Social Reproduction.................................................................................................................................. 304 Social Exclusion.......................................................................................................................................... 306 Environmental Justice.............................................................................................................................. 306 Residential Segregation........................................................................................................................... 307 Global Inequality........................................................................................................................................ 307 Heath and Healthcare Disparities in the US...................................................................................... 307 Intersectionality......................................................................................................................................... 308 Class Consciousness and False Consciousness................................................................................. 308 Statistics........................................................................................................................................................ 309 Study Types.................................................................................................................................................. 309 Unformatted Extras................................................................................................................................... 311 Requirements for generalizability....................................................................................................... 319 7 Sensory Perception Visual Cues When we look at something, we need to make inferences Visual cues allows us to perceptually organize by taking into account the following cues: depth, form, motion, constancy Humans have two eyes which allow them to receive visual cues from their environment by binocular cues. These give them a sense of depth. o This gives them retinal disparity. Eyes are ~2.5 inches apart which allows humans to get slightly different views of objects of world around. Gives humans an idea on depth. o Convergence: Gives humans an idea of depth as well based on how much eyeballs are turned. Gives humans a sense of depth. § Things far away – muscles of eyes relaxed. § Things close to us – muscles of eyes contract. Humans also have visual cues they receive which they do not need two eyes for. These are monocular cues. o These give humans a sense of form of an object § Relative size- Can infer with one eye. The closer an object it is perceived as being bigger. Gives us an idea of form. 8 § Interposition (overlap)- Perception that one object is in front of another. An object that is in the front is closer. § Relative height- things higher are perceived to be farther away than those that are lower. § Shading and contour- using light and shadows to perceive form depth/contours – crater/mountain. o Monocular cues can also give a sense of motion § Motion parallax- “relative motion” Things farther away move slower, closer moves faster. o Monocular cue of constancy § Constancy – Our perception of object doesn’t change even if the image cast on the retina is different. Different types of constancy include size constancy, shape constancy, color constancy. Size Constancy: One that appears larger because its closer, we still think it is the same size. Shape Constancy: a changing shape still maintains the same shape perception. 9 o Ex. A door opening means the shape is changing. But we still believe the door a rectangle Color Constancy: despite changes in lighting which change the image color falling on our retina, we understand (perceive) that the object is the same color. Sensory Adaptation Sensory adaptation: Our senses are adaptable and they can change their sensitivity to stimuli. o Hearing adaptation - inner ear muscle: higher noise = muscle contract (this dampens vibrations in inner ear, protects ear drum.) Takes a few seconds to kick in! So does not work for immediate noises like a gun shot, but it works for being at a rock concert for an entire afternoon o Touch - temperature receptors desensitized over time. o Smell – desensitized receptors in your nose to molecule sensory information over time. o Proprioception – is the sense of the position of the body in space i.e. “sense of balance/where you are in space.” § Experiment: goggles that make everything upside down and the perception of the world, and eventually you would accommodate over time, and flip it back over. o Sight – down regulation or up regulation to light intensity. § Down regulation: light adaptation. When it is bright out, pupils constrict (less light enters back of eye), and the desensitization of rods and cones become desensitized to light) § Up regulation: dark regulation. Pupils dilate-, rods and cones start synthesizing light sensitive molecules Weber’s Law 2 vs. 2.05 lb weight feel the same. 2 vs. 2.2 lb weight difference would be noticeable. The threshold at which you’re able to notice a change in any sensation is the just noticeable difference (JND) So now take 5 lb weight, in this case if you replace by 5.2 weight, might not be noticeable. But if you take a 5.5 lb it is noticeable. I = initial intensity of stimulus (2 or 5 lb), ΔI = JND (0.2 or 0.5). Thus, Weber’s Law is: o ΔI (JND)/I (initial intensity) = k (constant) o ex. 0.2/2 = 0.5/5 = 0.1, change must be 0.1 of initial intensity to be noticeable If we take Weber’s Law and rearrange it, we can see that it predicts a linear relationship between incremental threshold and background intensity. 10 o ΔI = Ik. o If you plot I against ΔI it’s constant Absolute Threshold of Sensation Absolute threshold of sensation: The minimum intensity of stimulus needed to detect a particular stimulus 50% of the time. At low levels of stimulus, some subjects can detect and some can’t. Also there are differences in an individual. Not the same as the difference threshold (JND – Just Noticeable Difference) – that’s the smallest difference that can be detected 50% of the time. Related but different concepts. Absolute threshold can be influenced by a # of factors. Not a fixed unchanging number. Particularly, it is influenced by a variety of Psychological states. o Expectations – ex. Are you expecting a text. o Experience (how familiar you are with it) – ex. Are you familiar of the phones text vibration sound. o Motivation – ex. Are you interested in the response of the text o Alertness – Are you awake our drowsy. Ex. You will notice text if you are awake Subliminal stimuli – stimuli below the absolute threshold of sensation. Somatosensation Receive information about the types of somatosensation, the Intensity, Timing, and Location Types: Temperature (thermoception), pressure (mechanoception), pain (nociception), and position (proprioception) Intensity – how quickly neurons fire for us to notice. Slow = low intensity, fast = high intensity. 11 Timing: Neuron encodes 3 ways for timing: non adapting, fast adapting, or slow adapting o Non-adapting- neuron consistency fires at a constant rate o Slow-adapting - neuron fires in beginning of stimulus and calms down after a while o Fast-adapting - neuron fires as soon as stimulus start…then stops firing. Starts again when stim stops). Location: Location-specific stimuli by nerves are sent to brain. Relies on dermatomes. *Note: This graph doesn’t relate rows to columns, read columns separately The Vestibular System A type of sensation. Balance and spatial orientation Comes from both inner ear and limbs. Focus on inner ear - in particular the semicircular canals (posterior, lateral, and anterior; each orthogonal to each other) Canal is filled with endolymph, and when we rotate the fluid shifts in the semicircular canals – allows us to detect what direction our head is moving in, and because we can detect how quickly the endolymph is moving we can determine the strength of rotation. Otolithic organs (utricle and saccule) help us to detect linear acceleration and head positioning. In these are CaCO3 (Calcium carbonate) crystals attached to hair cells in viscous gel. If we go from lying down to standing up, they move, and pull on hair cells, which triggers AP. These would not work very well w/o gravity! Buoyancy can have effects as well, particularly without visual cues on which way is up/down. Also contribute to dizziness and vertigo (when you or objects around you are moving when they are not) o Endolymph doesn’t stop spinning the same time as we do, so it continues moving and indicates to brain we’re still moving even when we’ve stopped – results in feeling of dizziness. 12 Signal Detection Theory – Part 1 Signal Detection Theory: Looks at how we make decision under conditions of uncertainty – discerning between important stimuli and unimportant “noise” At what point can we detect a signal o Origins in sonar – is signal a small fish vs. large whale. o Its role in psychology – Imagine being given a list. Then a second list. Now experimenter asks, which words on the second list were on the first. Person has to have uncertainty as they are not sure whether a certain word is exact or similar than the one in the first list. (Which words on second list were present on first list.) o Real world example – traffic lights. It’s foggy day & you have to decide when to start driving. How strong does a signal have to be for you to drive? Signal is present or absent (red). o Options: hit/miss/false alarm/correct rejection § Hit, the subject responded affirmative when a signal was present, § False Alarm, the subject perceived a signal when there was none present; § Correct Rejection, a correct negative answer for no signal § Miss, a negative response to a present signal 13 *Note: Do not mistake this for Type I/Type II errors. This is different terminology. Strength of a signal is variable d’, and c is strategy o d’: Strength § hit > miss (when there is a strong signal), § miss > hit (weak signal) o c: strategy § 2 strategies Conservative strategy - always say no unless 100% sure signal is present. Bad thing is might get some misses. Or liberal strategy- always say yes, even if get false alarms. Signal Detection Theory – Part 2 For any signal, have noise distribution (background). And get a second graph – the signal distribution. o The difference between means of the two is d’. So if signal shifted to right, d’ would be big and easy to detect. If left, d’ very small and more difficult to detect. o X-axis has intensity. o The strategy C can be expressed via choice of threshold – what threshold individual deems as necessary for them to say Yes vs. No. Ex. B, D, C, beta, just diff variables. o If we were to use the strategy B, let’s say choose this threshold à 2. So anything > 2 will say Yes, anything microphone -> transmitter (outside the skull) sends info to the receiver (inside skull). Then it sends info to the stimulator, into the cochlea, and cochlea converts electrical impulse into neural impulse that goes to brain. Restores some degree of hearing. Somatosensation xSomatosensation See Notes above 31 Sensory Adaptation and Amplification Sensory Adaptation is change over time of receptor to a constant stimulus – down regulation of a sensory receptor in the body o Ex. As you push down with hand, receptors experience constant pressure. But after few seconds receptors no longer fire. o Important because if cell is overexcited cell can die. Ex. If too much pain signal in pain receptor (capsaicin), cell can die. o Ex; light pressure receptor in your hand. They fire constantly, but over time they adapt and stop firing if there is no change in stimuli. Information does not get sent to the brain if there is no change in stimuli. Amplification is up regulation. Opposite of sensory adaptation. o Ex. Light hits photoreceptor in eye and can cause cell to fire. When cell fires AP, can be connected to 2 cells, which also fire AP and so on. By the time gets to the brain, it is amplified. Somatosensory Homunculus Somatosensory Homunculus: A map of your body in your brain. Information all comes to the “sensory strip”. It is a topological map of the entire body in the cortex. Different areas of the body have signals that go to different parts on this strip. This part of cortex/parietal lobe is called the sensory cortex – contains the homunculus. Info from body all ends up in this somatosensory cortex of the parietal lobe. Brain has information that comes from various different parts of the body. If there was a brain tumor, to figure out what part it’s in neurosurgeons can touch diff parts of cortex and stimulate them. If surgeon touches part of cortex patients can say they feel it. Do it to make sure they aren’t removing parts in sensation, which would make patients loose sensation in those areas. Proprioception and Kinaesthesia How can you walk in a pitch-black room? You rely on your sense of balance/position – proprioception. o Tiny little receptor/sensor (known as a spindle) located in our muscles sends signals that go up to spinal cord and to the brain. Spindle has a protein that is sensitive to stretching. o Sensors contract with muscles – so we’re able to tell how contracted or relaxed every muscle in our body is. o Cognitive awareness of your body in space. Subconscious. Not always thinking about it. Kinaesthesia is talking about movement of the body. Kinaesthesia is more behavioural. o You teach yourself how to move to successfully complete the task at hand. o Ex: “If I move in this direction, I will hit the baseball.” 32 Recap: Not the same, but share a lot in common – both help tell you where your body is in space. o Proprioception includes sense of balance/position, while kinesthesia includes sense of movement. (acronym Kinetics/similar to kinesthesia = movement) o Proprioception is cognitive, kinesthesia is behavioral Pain and Temperature Ability to sense Pain = nociception. Ability to sense temperature = thermoception Both temperature and nociception are SLOW In order for us to sense temperature, we rely on the TrypV1 receptor. o Interestingly, this receptor is also sensitive to pain. o There are thousands of these in membranes. Heat causes a conformational change (change in physical structure) in the protein. o When cell is poked, thousands of cells are broken up, and releases different molecules that bind to TrypV1 receptor. Causes change in conformational change, which activates the cell and sends signal to brain. 3 types of nerve fibres – fast, medium, slow. [Acronym: fast to slowest alphabetically A- B, A-D, C] o A-beta fibres - Fast ones are thick and covered in myelin (less resistance, high conductance) o A-delta fibres -– smaller diameter, less myelin. o C fibres - small diameter, unmyelinated (lingering sense of pain). Pain also changes conformation of receptors – capsaicin binds the TrypV1 receptor in your tongue, and triggers the same response. The sensory component would describe aspects of the intensity of pain. Affective refers to the experience of emotions Gate control theory of olfaction is a theory of the processes of nociception. The gate control theory of pain asserts that non-painful input closes the "gates" to painful input, which prevents pain sensation from traveling to the central nervous system. Therefore, stimulation by non-noxious input is able to suppress pain. “Fast blocks slow” Ronald Melzack and Patrick Wall. Taste (Gustation) and Smell (Olfaction) Pheromones Why do dogs pee on fire hydrant? There are molecules released in the urine, which can be sensed by other animals through the nose – pheromones. o They’re specialized olfactory cells. o Cause some sort of response in animal smelling them. 33 o Pheromone is a chemical signal released by 1 member of the species and sensed by another species to trigger an innate response. o Really important in animals, particularly insects – linked to mating, fighting, and communication. Specialized part of olfactory epithelium in animals – the accessory olfactory epithelium. It sends projections to the accessory olfactory bulb which then sends signals to the brain. o Within the accessory olfactory epithelium, you have a structure called the vomeronasal system. o In vomeronasal system, there are basal cells and apical cells. They have receptors at tips. o Molecule will come in and activate receptor on basal cell/apical cell here. Basal cell sends axon through accessory olfactory bulb to glomerulus, then mitral or tufted cell which eventually goes to the amygdala (part of the brain) o Amygdala is involved with emotion, aggression, mating etc. In temporal lobe, also involved in memory/decision making, emotional reactions o Signal transduction is where signal binds to receptor, which binds to GPCR. Depolarization. Signal goes to brain. o In humans have vomeronasal organ, but no accessory olfactory bulb. As a result, we rely very little on pheromones. Olfaction – Structure and Function When you have a cold, you aren’t able to taste things very well. o ex. When you eat, molecules travel up back of throat and some go into back of your nose. So you’re using your sense of smell in conjunction with taste. o If your smell is knocked out/closed, you can’t taste things as well. Smell is also known as olfaction Area in nostril called the olfactory epithelium (olfactory sensory cells). Separating the olfactory epithelium from the brain is the cribriform plate (bone with little holes that allow olfactory sensory to send projections to the brain). Above the cribriform plate is 34 an extension from the brain – olfactory bulb – a bundle of nerves that sends little projections through cribriform plate into the olfactory epithelium, which branch off. o At end of each connection are receptors, each sensitive to 1 type of molecule. o Molecule travels into nose, binds one of receptors on nerve endings. Zoom in on olfactory bulb o Imagine there’s olfactory cell sending projection to olfactory bulb. There are thousands of types of olfactory epithelial cells, each with diff receptor. These olfactory epithelial cells are located within the other epithelial cells. One, let’s say is sensitive to (has a receptor for) benzene rings. o When it binds to receptor, triggers cascade of events that cause cell to fire. AP will end up in olfactory bulb. All cells sensitive to benzene will fire to one olfactory bulb – called a glomerulus – designation point for various sensory olfactory cells that are sensitive to the same molecule. For example, a benzene glomerulus. o At the glomerulus, the receptors then synapse on another cell known as a mitral/tufted cell that project to the brain. This organization is there because it’s easier for one cell to send a projection to the brain instead of thousands. How does a molecule bind to a receptor and cause an AP? The molecule binds to the GPCR receptor on odor molecule à GPCR on olfactory epithelia à G-protein dissociates and causes a cascade of events inside the cell à G protein binds to ion channel which allows cells outside the cell to come insideà opens and triggers an AP à goes to cribriform plate à glomerulus à activate mitral/tufted cell à synapse to brain. Idea: 100 of different olfactory epithelial each sensitive to one particular molecule. They all send projections to one glomerulus respective to their specialization. Then they synapse onto a mitral/tufted cell which signals to the brain. Smell (olfaction) and taste (gustation) doesn’t synapse on to thalamus and hence are both ipsilateral while vision/hearing/touch are contralateral. The labeled-line theory of olfaction describes a scenario where each receptor would respond to specific stimuli and is directly linked to the brain. The vibrational theory of olfaction asserts that the vibrational frequency of a molecule gives that molecule its specific odor profile. Steric theory of olfaction, or shape theory, asserts that odors fit into receptors similar to a lock-and-key. Anosmia – inability to perceive order. (Acronym: aNOSEmia = Smell) The pathway for olfaction goes from the olfactory bulb to the amygdala and the piriform cortex. From there the signal is transmitted to the orbitofrontal cortex. Gustation – Structure and Function We have 5 main tastes, each taste depends on a specific receptor that is localized on the tongue – bitter, salty, sweet, sour, and umami (ability to taste glutamate). The gustatory system consists of taste receptor cells in taste buds. Taste buds, in turn, are contained in structures called papillae. 35 Taste buds are concentrated anteriorly (front) on the tongue. Taste buds can be fungiform (anterior), foliate (side), and circumvallate (back). o In each taste bud are the 5-receptor cells that can detect each taste. Each taste can be detected anywhere on the tongue. Each taste bud has cells specialized for each of the 5 tastes. o Mostly on anterior part of tongue. Fungiform papillae are mushroom-shaped structures located on the tip and sides of the tongue, which contain taste buds. Foliate papillae are folded structures at the back of the tongue on both sides, which contain taste buds. Circumvallate papillae are flat mound structures that are found at the back of the tongue and contain taste buds. Filiform papillae do not contain taste buds and exist all over the tongue. The center of the tongue contains only filiform papillae. This is why stimulation of the center of the tongue does not cause a taste sensation, while the back and perimeter produce a broad range of taste sensations. Tastant – a substance that stimulates the sense of taste Gustducin – a protein associated with the sensation of taste Front 2/3rd carries signals via 7th cranial nerve via the chorda tympani Posterior (Rear 1/3rd ) carries signals via the 9th and 10th cranial nerves (glossopharyngeal and vagus) Labelled lines model - Each taste bud receptor has 5 axons, all which send separate taste information to different parts of the gustatory (taste) cortex. Remain separate to the brain. And they all synapse on diff parts of the gustatory (taste) cortex. 36 o Ex. Glucose hits tongue àactivates sweet cell (because it has sweet sensitive receptors), triggers cascade of events so cell depolarizes, and travels down axon to the brain. o Glucose binds GPCR, conformational change, G-protein dissociates, opens ion channels, cause cell to depolarize and fire an AP Sweet, umami, and bitter cells rely on GPCR receptors. Sour and salty rely on ion channels. (Acronym: SOdium, which is an ion channel is SOur and salty, think salt.) They bind to receptor directly, ex. NaCl binds to receptor and causes ion channel to open, and + ions outside flow in. Cell depolarizes and fires an AP. o Salty tastants bind to salt receptors which detect the presence of sodium ions and should not be chosen by the researchers. o Sour tastants bind to sourness receptors that react with hydrogen cations (H+). Once H+ binds to the receptor, it closes potassium channels. What happens if we put salty receptor inside a sweet cell? Receptors in membrane bind to glucose. But let’s insert a salty receptor. Since axon from cell leads to brain, if NaCl comes in, it activates the receptor, + ions go inside, sweet cell depolarizes and fires AP, and brain interprets it as a sweet signal. Put a salty receptor in a sweet cell, can trick your brain into thinking salt is sugar! Taste/Smell - Do not synapse on the thalamus. Oribofrontal cortex is first place of integration. 37 Sleep and Consciousness States of Consciousness Consciousness is awareness of our self and environment. Can have different levels of consciousness (diff levels of awareness) and can be natural or be induced by external factors such as drugs or internal such as mental efforts. States range from alertness to sleep. Alertness – you’re awake, aware of who you are, what’s going on in the environment, focus your attention, engage in conformation, code info to your memory. Daydreaming- feel more relaxed, not as focussed as alertness. Can also be light meditation (self-induced) Drowsiness - just before falling asleep/after waking up. Can also be self-induced in deep meditation. Sleep – not aware of self or world around you. Electroencephalograms (EEGs) can measure brainwaves. o 4 main types: alpha, beta, delta, theta o Each type oscillates at diff frequency and associated with different type of consciousness. § Beta (12-30Hz) – associated with awake/concentration. If you are alert for too long, beta levels get high and you experience increased stress, anxiety, restlessness- constant awakened alertness. § Alpha (8-13 Hz) – in daydreaming state. Lower frequency than beta waves. Disappear in drowsiness but reappear later in deep sleep. § Theta (4-7 Hz) – slower/lower frequency than alpha waves. Drowsiness/right after you fall asleep/when you are sleeping lightly. § Delta (0.5-3 Hz) – Slower/lower frequency than theta waves. Deep sleep or coma. o In sleep, the type of wave varies by stage. You might not be aware of shifting from one stage of sleep to another, but your brain knows. You have set of neurons that fire rhythmically) in your CNS , which lead to neural rhythms (also called oscillations and commonly known as brain waves) that can be measured by EEGs. Sleep Stages and Circadian Rhythms Sleep stages: Your brain goes through distinct brain patterns during sleep. 4 main stages that occur in 90 min cycles. First three stages are categorized in non-rapid eye movement sleep (non-REM) – N1, N2, N3 o N1 (Stage 1): Dominated by theta waves. 38 § Strange sensations – hypnagonic hallucinations, hearing or seeing things that aren’t there ex. seeing flash of light, or someone calling your name, doorbell, etc. § Or the Tetris effect – if you play Tetris right before bed, you might see visual images of blocks during sleep. OR Ex. Been on a boat all day, you might still feel like you are on water even when on dry land § Also a feeling of falling – hypnic jerks- muscle twitches you sometimes experience as you fall asleep. o N2 (Stage 2) – deeper stage of sleep. People in N2 are harder to awaken. We see more theta waves, as well as sleep spindles and K-complexes. § Sleep spindles are a burst of rapid brain activity. Some researchers think that sleep spindles help inhibit certain perceptions so we maintain a tranquil state during sleep. Sleep spindles in some parts of brain associated with ability to sleep through loud noises. § K-complexes - supress cortical arousal and keep you asleep. Also help sleep-based memory consolidation (some memories are transferred to long term memory during sleep, particularly declarative/explicit memories). Even though they occur naturally, you can also make them occur by gently touching someone sleeping. “that touch was not threatening, stay asleep brain” o N3 (Stage 3) – slow wave sleep. Very difficult to awaken. Characterized by delta waves. Where sleep walking/talking in sleep happens. Declarative Memory consolidation. “regular breathing and regular slow brain waves” REM (rapid-eye movement) stage. Eyes move rapidly beneath your eyelids but most of your other muscles are paralyzed. Most dreaming occurs during REM sleep, so paralysation inhibits actions. Most important for memory consolidation. Formation of episodic memories. Combination of alpha, beta, and dyssynchronous waves, similar to beta waves seen when awake. Acronym: BATS-Drink Blood (beta alpha theta sleep- spindle/K-complex delta beta) o Sometimes called paradoxical sleep, because brain is active and awake but body prevents it from doing anything o Waking up during REM sleep allows you to remember your dream o REM sleep more before you wake up o More N3 sleep right as you go to bed o Consolidate procedural memories Cycle through these 4-5 times per sleep, each one 90 minutes. Order within cycle goes from N1 -> N2 -> N3 -> N2 -> REM à N1. How long each stage lasts depends on how long you’ve been asleep and your age (babies spend more time in REM sleep) 39 Circadian Rhythms – why you get sleepy in afternoon. They’re our regular body rhythms across 24-hour period. Controlled by melatonin, produced in the pineal gland. o Control our body temperature, sleep cycle, etc. o Daylight is big queue, even artificial light. o Also change as you age – younger people are night owls, but older people go to bed early. o Can prevent you from sleeping in. Dreaming Everybody dreams during REM sleep. Can tell someone is dreaming because eyes are moving rapidly under eyelids, and brainwaves look like they are completely awake. These are the memorable dreams (NREM ones are not memorable) Activity in prefrontal cortex during REM sleep is decreased – part responsible for logic. Why things in our dreams can defy logic and don’t seem weird. Why do dreams occur? Few theories: Sigmund Freud o Dreams are our unconscious thoughts and desires that need to be interpreted. Little scientific support. Evolutionary biology o Threat simulation, to prepare for real world. o Problem solving o No purpose Other o Maintain brain flexibility – allows us to learn and be creative when we are awake o Consolidate thoughts to long-term memory, and cleaning up thoughts. People who learn + sleep retain more than those who do not sleep. But role of REM is unclear. 40 o Preserve and developing neural pathways. Because infants constantly developing new neural networks spend most of time in REM sleep. o Memory consolidation theorists believe memory consolidated in deep sleep. Dream Theories – Freud and Activation Synthesis Hypothesis Do our dreams have a meaning? o Sigmund Freud’s theory of dreams says dreams represent our unconscious feelings/urges/thoughts. Like an iceberg. § What happens? Literal meaning. Manifest content. ex. Monster chasing you § What is hidden meaning? Latent content. ex. Job pushing you out. § Dreams have meaning. Interpreting them can help us resolve and identify hidden conflict. o Activation Synthesis Hypothesis § Brain gets a lot of neural impulses in brainstem, which is sometimes interpreted by the frontal cortex. § Brainstem = activation, and cortex = synthesis. § Our brain is simply trying to find meaning from random brain activity. Therefore dreams might not have meaning. Sleep Disorders People with sleep deprivation might be more irritable and have poorer memory and attention. Could be dangerous when it comes to flying airplanes or driving cars. Interesting more sleep = less accidents, less sleep = more accidents o Also more susceptible to obesity – body makes more cortisol, and the hunger hormone (ghrelin). o Can also increase your risk for depression. REM sleep helps brain process emotional experiences, which can help protect against depression (not certain about this link). o Can get back on track by paying back “sleep debt” (paying back sleep) How much is enough sleep? 7-8 hours for adults. Varies with age and individual. Babies need a lot more. o An infant (age 4 months to 11 months) should get at least 12 hours. o A preschooler (age 3 to 5 years old) should get at least 10 hours of sleep a night. o A school age child (age 6 to 13 years old) should get at least 9 hours of sleep a night. Older adults = at least 7 hrs More serious form – insomnia (persistent trouble falling asleep or staying asleep). Various medications but taking them too long leads to dependence and tolerance. If you rely on medication, you become more habituated to it and need more to get the same effects. 41 o Treatments can involve psychological training and lifestyle changes (exercising regularly or relaxing before bed). This is a better alternative to medication. Other end of spectrum is narcolepsy – can’t help themselves from falling asleep. Various fits of sleepiness, going into REM sleep. Have fits (usually 5 minutes) that can occur any time. 1 in 2000. o Cause is not completely known. Indications that it is genetic, and linked to absence of alertness neurotransmitter. o Neurochemical interventions can cause someone to overcome narcolepsy potentially. Sleep apnea – 1 in 20 people. People with it are often unaware. Stop breathing while sleeping – body realizes you’re not getting enough oxygen, wake up just long enough to gasp for air and fall back asleep without realizing. Can happen 100x/night! o Don’t get enough N3 (Stage 3; slow-wave) sleep. o Snoring is an indication, or fatigue in morning after full night of sleep. Sleepwalking/sleep talking – mostly genetic, occur during N3 (stage 3; slow wave) and are harmless. Occur more often in children (partly because they have more N3 stage sleep than adults). xBreathing-Related Sleep Disorders See below notes Hypnosis and Meditation Induced States of Consciousness: Hypnosis + medication are examples. Does not occur naturally. Hypnotism usually involves getting person to relax and focus on breathing, and they become more susceptible to suggestion in this state – but only if they want to. More alpha waves in this stage – an awake but relaxed state. o Some use hypnosis to retrieve memories, very dangerous because memories are malleable. Can create false memories (False memory)- memories that incorporate hypnotizers expectations even when not intended. o Some people feel that hypnosis can control pain. Might help us inhibit our attention to painful stimuli. Only works if you think it will work. o 2 theories for how it works: Dissociation Theory (hypnotism is an extreme form of divided consciousness) and the Social Influence Theory (people do and report what’s expected of them, like actors caught up in their roles) o Refocused attention, so sometimes it’s used to treat pain. Reduced activity in areas that process sensory input. Although it doesn’t block it out, it might inhibit attention that inhibit. Meditation – training people to self-regulate their attention and awareness. Can be guided and focused on something in particular, like breathing, but meditation can also be unfocussed – mind wanders freely. o More alpha waves than normal relaxation in light meditation. 42 o In deep meditation have increased theta waves in brain (only experts typically) o No long term studies. But those who regularly go to deep meditation, have shown increased activity in prefrontal cortex, right hippocampus, and right anterior insula – increased attention control (the goal of meditation). o Can be helpful for people with ADHD, or in aging. Drug Dependence Overview of Psychoactive Drugs Psychoactive Drugs: Drugs that can alter our consciousness, and perceptions. They can alter our perception, increase our mood, calm us down, make us feel more alert, etc. Classified by action and effects they have on our bodies. 4 main categories of psychoactive drugs: depressants, stimulants, hallucinogens Depressants are drugs that lower your body’s basic functions and neural activity, lower CNS activity (decrease arousal/stimulation in areas of our brain) ex. Decrease Heart rate, decreased BP, decreased processing/reaction time (makes us act/think slowly), etc. Three categories: alcohol, barbiturates, and benzodiazepines o Vasodilate at low, vasoconstrictor at high o The most popular depressant is alcohol. § Decreased inhibitions, so decreasing cognitive control § Lack of coordination, slurring of speech § Think more slowly, disrupt REM sleep (and form memories) o Barbiturates – used to induce sleep or reduce anxiety (calm them down) Depress your CNS. Anesthesia or anticonvulsant (drugs that reduce seizures) § Not often prescribed due to negative side effects such as reduced memory, judgement and concentration, with alcohol can lead to death (most drugs w/ alcohol are bad) § -barbital o Benzodiazepines are the most commonly prescribed suppressant. Subscribed for same things as barbiturates - sleep aids (to treat insomnia) or anti-anxiety or seizures (anticonvulsant) § Enhance your brain’s response to GABA. They open up GABA-activated chloride (Cl-) channels in your neurons, and make neurons more (-) charged. § 3 types: short, intermediate, and long-acting. Short and intermediate are usually for sleep, while long acting is for anxiety. § -zelam, -zolam § Benzodiazepines and alcohol bind to a site on the GABAA receptor complex that regulates the sensitivity of the receptor complex. Stimulants are drugs that excite your CNS, increase HR/BP, alertness, more awake, more energetic. Can cause people to feel glittery. Examples include: 43 o Caffeine, Amphetamines (Adderall), Methamphetamines (Meth), MDMA (Molly/Ecstasy), Cocaine, Nicotine, THC (Marijuana/Cannabis – also a hallucinogen/depressant) o Cocaine – can be used as a anesthetic/ o Vasodilate o Effect is similar to stress, increased glucose metabolism in brain. § Cocaine: blocks dopamine reuptake. § Amphetamines both block dopamine reuptake and stimulate presynaptic dopamine release. § Caffeine inhibits the enzyme that breaks down cAMP (cyclic adenosine monophosphate). § Nicotine acts on acetylcholine § THC works on anandamide. Increase dopamine and GABA activity. o Stimulants and depressants are functionally opposite but don’t actually work on the same things at a neurochemical level. Drinking coffee after drinking alcohol won’t make you sober; it will just make you an alert drunk person. o Vasoconstrictor Hallucinogens (referred to as psychedelics): o Distorted perceptions/hallucinations - seeing or hearing things different from how things actually are. o Heighted sensations. Based on reality but is different from what’s going on in the world around o Can give them energy or calm them down o Emotional responses - Feeling of connectedness and mood swings (changing moods) o Exact effect can be different depending on an individual’s personality or who they are/who they are win § Examples:, mescaline, peyote, PCP, LSD, psilocybin (active ingredient in mushroom) o LSD modifies serotonin neurotransmission, especially the 5-HT2 receptor family. o Dilation of pupil (mydriasis) Opiates/Opioids o Opiates – natural o Opioids – synthetic o Like depressants: Decrease CNS function, decrease HR/BP, cause relaxation, induce sleep (hence can be used to treat pain and anxiety). o BUT it is NOT a depressant. Work on different mechanisms at the neurochemical level o Analgesic – reduce perception of pain o ex. heroine, codeine, morphine, oxycodone o Used to treat pain because they act at body’s receptor sites for endorphins. o Different class than depressants, even though overlapping for anxiety, rest act on GABA receptors while opiates act on endorphin Receptors 44 o Lead to euphoria, why taken recreationally o An opiate binds to opioid receptors by mimicking endorphins. o Vasodilator, and pupillary constriction o Die by respiratory failure Cannabis (Marijuana) – a mix of all. Can be a hallucinogen and also be a depressant or a stimulant MDMA can be a stimulant or hallucinogen. Drugs can be classified by legal status or how likely they are to be abused o Active substance: THC o Cannabis metabolites can be present in the blood of users for up to 3 months. o Tolerance can increase the amount of cannabis needed for impairment and THC metabolites and many other constituents of cannabis accumulate in fat cells for three months or more. Psychoactive Drugs: Depressants and Opiates Psychoactive Drugs: Alter your consciousness by altering your perceptions and moods. Depressants: lower HR, reaction time, processing speed, slowing of neural processing/sympathetic nervous system. Act on GABA (inhibitory neuro transmitter) receptors, open up Cl- channels on your neuron and inhibit excitation. Alcohol – most common depressant. o Common depressant symptoms o Disrupts REM cycle – for memories /new synapses is reduced 45 o Disinhibited - removes inhibitions. Acting on impulses. reduced self-awareness and control o Alcohol is a CNS depressant that is absorbed through the cell membrane. Barbiturates: used to be called a tranquilizer. Depressant. o Induce sleep, reduce anxiety. o Side effects: reduced memory + judgement + concentration o Combined with alcohol = leads to death Benzodiazepines (Benzos): depressant. Commonly prescribed. o Short-acting (preferred for insomnia) , intermediate acting, long acting (preferred to treat anxiety) Opiates: can be used to treat pain/anxiety o Examples: Opiates: (acronym: T = Tree = Natural). Morphine/codeine o Opioids: oxycodone/hydrocodone (prescription), heroin o Act on endorphin receptors. NOT a DEPRESSANT but can be used for anxiety/pain o Used to treat pain (endorphins) o Euphoria o Methadone = treatment Drugs and opiates can be addictive Psychoactive Drugs: Stimulants Stimulate –stimulate or intensity neural activity/bodily functions. Range from caffeine to cocaine, amphetamines, methamphetamines, and ecstasy. In between is nicotine. Caffeine (inhibits adenosine receptors) can disrupt your sleep. Increases energy, can disrupt sleep for several hours Nicotine - Increase HR/BP. also disrupts sleep and can suppress appetite (why some people gain weight when they quit smoking) o At high levels, nicotine can cause muscles to relax and release stress-reducing neurotransmitters (to counteract hyper alertness). o Nicotine is a CNS stimulant, which works as an acetylcholine receptor agonist. Both caffeine and nicotine: o Physiologically addicting. o Withdrawal symptoms from both: § From coffee: irritability, difficulty concentrating, depression, § Nicotine: (more addictive than coffee) Anxiety, insomnia, irritability, distractibility Cocaine is even stronger stimulant – causes brain to releases so much dopamine, serotonin, and norepinephrine that it depletes your brain’s supply. Intense crash and very depressed when it wears off. o Regular users can experience disturbances, emotional suspicion, convulsions, cardiac arrest, and respiratory failure. 46 Amphetamines and methamphetamines also trigger release of dopamine, feeling of euphoria for up to 8 hours. Once effect wears off - experience irritability, insomnia, seizures, depression o Meth is highly addictive. o Long-term Meth addicts may lose ability to maintain normal level of dopamine because brain tries to adjust to intense highs. o Amphetamines block the reuptake of dopamine, which stimulates an increase in the release of dopamine from the presynaptic membrane. Psychoactive Drugs: Hallucinogens Hallucinogens: These drugs cause hallucinations, altered perception/sensations. Many types of hallucinations. Some even have medical uses. Ecstasy/MDMA/Molly– synthetic drug between a stimulant and hallucinogen. o Like stimulant - Increases dopamine and serotonin and euphoria. Also stimulates the body’s CNS. Effects include: high BP, dehydration, overheating, death § Can damage neurons that produce serotonin, which has several functions including moderating mood. No serotonin = depressed mood o Causes hallucinogen - hallucinations and heightened sensations, ex. artificial feeling of social connectedness and intimacy LSD – Prototypical hallucinogen. Interferes with serotonin, which causes people to experience hallucinations. o Hallucinations are visual instead of auditory Marijuana is also a mild hallucinogen. Main active chemical is THC, which heightens sensitivity to sounds, tastes, smells. o Like alcohol, (depressant) - reduces inhibition, impairs motor and coordination skills, perceptual skills o Disrupt memory formation and short-term recall. o Stays in body up to a week’s so regular users need less of the drug rather than more to receive the same high. o Used as medicine to relieve pain and nausea Some hallucinogens are used for PTSD treatment. Allow people to access painful memories from past that’s detached from strong emotions – so they can come to terms with it. Drug Dependence and Homeostasis Homeostasis is how you maintain temperature, heartbeat, metabolism etc. Occurs even when you are resting. Takes place when you take drugs. For example, if you take amphetamines (stimulant that increases your heart rate), your body quickly tries to lower HR and get back to normal. Brain is smart about this. o If regular drug user, might take it at same time of day or at the same location. o For example, pretend you are cocaine addict and you are always in the same room when you inject yourself with cocaine. Your brain starts to recognize 47 external cues like room, needles etc (the whole process of getting cocaine) before you get cocaine. Your brain tells body to get head start – lowers HR before you take drugs –this is why you need higher dose over time. Habituation. What would happen if you get those cues and don’t get the drug? You get a crash. Your body is below homeostasis (lower HR/metabolism). No high (which would occur if you took the drug) to counteract the slowing down your body has created. If you’re in a new location but take same level of drugs, you might get overdose. This is because in the new location your body has not prepared by reducing HR/metabolism. Routes of Drug Entry Routes of Entry: Oral, injection, inhalation, Oral is ingesting something, one of slowest routes because goes through GI tract – half hour. Ex. Pill, alcohol. Inhalation is breathing or snorting or smoking, because once you inhale goes straight to brain. Insufflation, inhaling drugs through the nose, is highly addictive but less addictive than drugs that are injected. – 10 seconds. faster Ex. Tobacco or cocaine. Injection- most direct, intravenous means goes right to vein. Takes effects within seconds. Fastest Can be very dangerous (likely to inject bacteria and unexpected toxins) especially when using an infected needle. Transdermal – drug is absorbed through skin, ex. Nicotine patch. Drug in patch has to be pretty potent, released into bloodstream over several hours. o Transdermal administration occurs slowly, since the drugs have to be absorbed through the skin before the effects can be felt. Intramuscular –needle stuck into muscle. Can deliver drugs to your system slowly or quickly. o Ex: Quick Delivery - epiPen – given to someone experiencing an allergic reaction which starts closing airways. EpiPen delivers epinephrine quickly and allows airways to open). Usually on thigh because it has the most access points to blood vessels o Ex: Slow Delivery Vaccines. Intramuscular delivery of vaccines is why your arm gets so sore after shots. 48 o Intramuscular injection is the fastest route of entry. Most abused drugs are injected intravenously, however. Faster route of entry = more addictive potential. Reward Pathway in the Brain When you first experience happiness/reward (verbal-praise pleasure, hug, ate cake) your brain is responding. Your brain says, “this was good”, “let’s do it again” (occurs in response to food, social interactions, sex, and stimulants such as cocaine, amphetamines, metaemphatime, MDMA, nicotine, caffeine). The drugs that activate this drug circuit more are more addictive. Brain releases neurotransmitter called dopamine. Produced in the ventral tegmental area (VTA), in the midbrain. o VTA sends dopamine to the amygdala (controls emotions), nucleus accumbens (NAcc , controls motor functions), prefrontal cortex (focus attention and planning), and hippocampus (part of the temporal lobe, involved in memory formation). o NAcc, amygdala and hippocampus are part of the mesolimbic pathway. Different stimuli active circuit to diff degrees. VTA releases dopamine to parts of brain that have dopamine uptake receptors– o Amygdala (connected to hippocampus that controls emotion) says this was enjoyable. § ex. This cake is delicious, I love this cake. I am feeling so happy right now. o Hippocampus remembers everything about this environments so we can do it again, § ex: Where am I at? Where am I eating this cake? Who am I with? Let’s remember things about this experience o nucleus accumbens – controls motor function § ex. says let’s take another bite. o Prefrontal cortex focuses attention § ex. puts attention to the cake. o You do

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