HSC1010 The Brain and the Mind - Part 1 Lecture Notes PDF

HSC1010 The Brain and the Mind Part 1: Brain, Sensation & Perception Presented by: Dr Peter Tay, Assistant Professor in Psychology Developed by: Dr Angela Papadimitriou, Clinical Psychologist & Dr Peter Tay Learning Objectives Explain the role of biology in psychology Under...

HSC1010 The Brain and the Mind Part 1: Brain, Sensation & Perception Presented by: Dr Peter Tay, Assistant Professor in Psychology Developed by: Dr Angela Papadimitriou, Clinical Psychologist & Dr Peter Tay Learning Objectives Explain the role of biology in psychology Understand the role of the nervous system and the function of its components Explain role of somatic & autonomic nervous systems Describe structure and communication of neurons Understand role of endocrine system and the function of hormones on behaviour Identify main brain structures and their functions Understand role of limbic system and the functions of its components Describe functions of different areas of cerebral cortex and lateralisation …Learning Objectives Understand cognitive neuroscience Explain sleep process, its importance & different stages Identify sleep deprivation effects and sleep disorders Understand impact of psychoactive drugs on consciousness and physiology Distinguish between sensation and perception Understand sensory thresholds and habituation Describe organs, stimuli and receptors involved in 5 senses Understand key visual perception concepts Describe functions of somesthetic senses Biology & Psychology Why are psychologists concerned with biology? Everything psychological is also biological: we are biopsychosocial systems To understand the complex organism of a human being To understand how the brain, nerves, and glands interact to control feelings, thoughts and behaviours The Biological Perspective Biological Perspective: focuses on the links between biology and behaviour Biological Psychology: branch of neuroscience that examines the biological bases of psychological processes, behaviour and learning Psychologists specialising in this branch of neuroscience: Behavioural neuroscientists, neuropsychologists, behaviour geneticists, physiological psychologists, biopsychologists Brain Spinal Cord Peripheral and Autonomic Systems Neurons The Nervous System The Nervous System (NS) Body’s electrochemical communication network Gathers & processes information Produces responses to stimuli Coordinates operations of different cells NS Comprises: Central Nervous System (CNS) Peripheral Nervous System (PNS) Central Nervous System (CNS) CNS: The central processing unit. Comprises: Brain: interprets and stores information and sends orders to muscles, glands and organs Spinal Cord: pathway connecting the brain and the peripheral nervous system (PNS) collection of neurons and supportive tissue running from the base of the brain down the center of the back, protected by a column of bones (spinal column) Peripheral Nervous System (PNS) PNS transmits information to and from CNS Contains all portions of NS (outside brain & spinal cord) right down to nerves in the tips of fingers and toes Includes sensory & motor nerves connecting CNS to the rest of the body PNS comprises: Autonomic Nervous System Somatic Nervous System Autonomic Nervous System (ANS) Controls the functioning of internal organs (e.g., heart, stomach) glands and blood vessels Like an auto pilot, ANS usually operates on its own but may be consciously overridden ANS comprises 2 parts working together, in opposing ways, to adjust the body to changing circumstances: Sympathetic NS (arousing): mobilises bodily resources and increases the output of energy during emotion and stress Parasympathetic NS (calming): – enables body to conserve and – restore energy, slows things down – & keeps things running smoothly Autonomic Nervous System Psychology, 11th ed. 2015 Myers & Dewall Somatic Nervous System (SNS) Controls the body’s skeletal muscles Includes nerves that are connected to sensory receptors (cells that allow you to sense the world) and skeletal muscles (that permit voluntary action) SNS comprises: Sensory input: carries messages from senses to CNS Motor output: carries messages from CNS to muscles and glands Nervous System (NS) - Summary Psychology, 4th ed. 2015 Ciccarelli & White Communication in the NS NS building blocks: neurons or nerve cells: the communication specialists, transmitting information to, from, and within the CNS glia or glia cells: hold neurons together, as well as nourish, insulate, and protect them Structure of the Neuron dendrites: branch-like structures that receive information from other neurons and transmit it to the cell body Soma: the cell body that keeps entire cell alive and determines whether it will fire axon: neuron’s tube-like extension that transmits messages to other neurons, muscles or gland cells axon terminals: terminal branches of axon myelin sheath: fatty insulation surrounding the axon, helps speed the neural impulses myelin sheath degeneration: multiple sclerosis (communication to muscles slows, loss of muscle control) Structure of the Neuron Nerves: Bundles of nerve fibers (mainly axons) in PNS. Human body has 43 pairs of peripheral nerves, 12 pairs in the head Psychology, 11th ed. 2015 Myers & Dewall How Neurons Communicate Electrical Process: within a neuron Action potential: a neural impulse; a brief electrical charge that travels down an axon Information is pushed through the axon based on a process of positive and negative charges of electrical atoms (ions) Chemical Process: between neurons Neurotransmitter: a chemical substance that is released by a transmitting neuron at the synapse and that alters the activity of a receiving neuron Cleaning Up Process Reuptake: process of reabsorbing excess neurotransmitters by the sending neuron How Neurons Communicate  How Neurons Communicate Synapse: the junction between the axon tip of the sending neuron and the dendrite of the receiving neuron Psychology, 11th ed. 2015 Myers & Dewall  Some Neurotransmitter Functions Examples of how drugs affect neurotransmitters: Cocaine blocks the reuptake of dopamine, allowing dopamine to stay active longer SSRIs, used for depression, block the reuptake of serotonin, extra serotonin improves mood Neurotransmitter Function Malfunctions Dopamine (DA) Influences movement, Oversupply → schizophrenia learning, attention, Undersupply → Parkinson’s disease, depression sensations of pleasure Serotonin (5-HT) Affects mood, appetite, Undersupply → depression, sleep and eating disorders sleep, anxiety Acetylcholine (ACh) Enables muscle action, Oversupply → muscle contraction, convulsions learning and memory Undersupply → Alzheimer's disease Norepinephrine (NE) Helps control alertness and Oversupply → stress and panic disorder; Undersupply → arousal depression Gaba-amino butyric Involved in sleep and inhibits Undersupply → seizures, tremors and insomnia (GABA) movement Endorphins Involved in pain relief Oversupply → insensitivity to pain; Undersupply → pain hypersensitivity, immune problems Endocrine System and Hormones Hindbrain, Midbrain and Forebrain The Limbic System The Hemispheres Brain and Hormones Long Distance Messengers Endocrine System (ES): 2nd communication system interconnected with the NS Hormones: 2nd class of chemical messengers secreted by endocrine glands (e.g., pancreas, ovaries, testes, adrenal glands) Hormones travel through the bloodstream to organs and cells far from their point of origin Hormones acting on brain affect interest in sex, food and aggression Both ES & NS produce chemicals that act on receptors elsewhere. NS in fraction of second; ES taking several seconds Endocrine Glands & Hormones Pituitary gland: located in the brain, secretes human growth hormone Pineal gland: located near the base of the cerebrum, secretes melatonin (biological rhythms & sleep) Thyroid gland: found in the neck, secretes thyroxin (growth & metabolism) Pancreas: controls the levels of sugar in the blood, secretes insulin and glucagon Gonads: located in ovaries and testes regulate sexual behavior & reproduction Adrenal glands: located at top of each kidney secrete over 30 hormones (corticoids/steroids) to control stress reactions Endocrine Glands & Hormones Mapping the Brain Lesioning Studies: examining brain areas that are damaged in animals and people; electrical current (via electrode) destroys target neurons Brain Stimulation: electrical stimulation to disrupt/enhance brain areas, and study changes in behaviour and cognition Deep Brain Stimulation (DBS): stimulating brain from the inside (invasive) – treatment for Parkinson’s Disease, Seizures, Chronic Pain Transcranial Magnetic Stimulation (TMS): stimulating brain from the outside with magnetic impulses (non-invasive) – PTSD & depression Mapping the Brain Mapping the Brain Mapping Structure: Computed Tomography (CT): Using X-rays to map brain “slices” (tumours, stroke damage, metal) Magnetic Resonance Imaging (MRI): Using magnetic fields & radio receivers for detailed (and 3D) imaging of brain tissue Mapping the Brain Mapping Function: Electroencephalogram (EEG): amplified recording of the waves of electrical activity sweeping across the brain’s surface, measured by electrodes placed on the scalp Positron Emission Tomography (PET): visual display of brain activity that detects where a radioactive form of glucose goes while the brain performs a given task Functional MRI (fMRI): tracking changes in blood oxygen levels (increased levels=increased functioning) to study brain activity linked with specific thoughts & behaviour Brain Structures Brain divided into Hindbrain: functions essential to maintain life Midbrain: connects hindbrain and forebrain, important for sensory & motor functions Forebrain: higher functioning (thinking, decision-making) Hindbrain The Brain Stem: oldest & innermost region; extension of spinal cord. Comprises: Medulla: controls heartbeat, breathing Pons: influences sleep, waking & dreaming Reticular Formation: nerve network running from hindbrain through midbrain to forebrain, controlling arousal and attention Cerebellum (little brain): regulates movement and balance; involved in some cognitive functions Forebrain The largest and most highly developed structure. Comprises: Limbic System: emotions, motivation, memory & learning Cerebrum: largest brain structure, controls sensory, motor and cognitive processes Cerebral Hemispheres Cerebral Cortex The Limbic System Thalamus: brain’s sensory control centre; receives information from all senses (except smell) and routes it to higher brain regions responsible for vision, hearing, touch & taste Hypothalamus: regulates survival needs (thirst, hunger, sleeping, body temperature) & emotions (controls pituitary gland- hormones) Hippocampus: forming long-term memories Amygdala: arousal and regulation of emotion; initial response to sensory information (fear) Cingulate Cortex: limbic structure found in cortex; influences emotional & cognitive processing The Limbic System Cerebrum Cerebral Hemispheres: the 2 halves (left & right) of the cerebrum connected by the corpus callosum Cerebral Cortex: the outer layer of the cerebrum (grey matter), covering the cerebral hemispheres responsible for higher mental functions. Comprises: frontal lobes: complex decision-making, planning, memory, personality and social judgement. Includes motor cortex & Broca’s area (speech production) temporal lobes: hearing (primary auditory cortex; auditory association cortex); Wernicke’s area (meaning of words) parietal lobes: receives sensory input for touch & body position (somatosensory cortex) occipital lobes: receive visual information (primary visual cortex; visual association cortex) Subdivisions of Cortex Brain’s Two Hemispheres The 2 hemispheres communicate via the corpus callosum Right hemisphere controls left side of body & Left hemisphere controls right side of body Lateralization: specialization of each hemisphere in particular operations In most mental activities, 2 sides cooperate Brain’s Two Hemispheres The Biological Perspective Experience and the Brain Stimulating environments increases synaptic connections; unused connections are trimmed Plasticity: brain’s ability to adapt to new circumstances Gender differences in the brain Brain scans: Some anatomical and functional differences; however, significance of this is unclear Similarities are greater than differences Brain difference ≠ behavioural difference Differences cannot be replicated Differences could be attributed to behaviour and experiences (rather than gender) Consciousness Sleep Psychoactive Drugs Neurological Functions Biology of Consciousness Cognitive Neuroscience: interdisciplinary study of brain activity linked with mental processes (perception, thinking, memory, language) relating specific brain sites to conscious experiences consciousness: generated by action potentials in communication among neurons producing a specific perception, memory, experience in awareness Dual processing: information is often simultaneously processed on separate conscious & unconscious tracks Parallel processing: processing many aspects of a problem simultaneously (brain’s natural mode) Selective Attention: conscious awareness focussed on a particular stimulus (cocktail party effect) Sleep Sleep: periodic loss of consciousness; distinct from unconsciousness (coma, anaesthesia) Biological rhythms: natural cycles of activity body goes through (e.g., short: heartbeat, long: menstrual cycle; mood) Sleep-Wake cycle: Circadian Rhythm (circa: about; diem: day) 24-hour cycle Circadian Rhythm controlled by the brain Suprachiasmatic Nucleus (SCN) in hypothalamus biological clock responds to light & dark changes (jetlag: clock out of sync) regulates levels of hormones & neurotransmitters melatonin (pineal gland): ↑ dark ↓ light serotonin: ↑ awake ↓ asleep Sleep Stages 2 Sleep Periods (Kleitman 1955) cycle of ~ 90mins: Rapid Eye Movement (REM): relatively active (Non-REM/N): deeper & restful state Sleep cycle: various stages repeated 4-5 times a night Sleep stages defined by brain-wave activity by EEG N1: light sleep, drifting in & out consciousness N2: body temperature & heart rate ↓, breathing shallow, minor noises won’t wake N3 & N4: breathing & pulse ↓, muscles relax, deep sleep, hard to wake (sleepwalking & sleep disorders) REM: brain active, body inactive (paradoxical sleep)  Sleep Stages Invitation to Psychology, 6th ed. 2015 Wade, Tavris & Garry Why do we need sleep? Sleep is necessary for bodily restoration and for normal mental functioning Two Theories of Sleep: 1) Adaptive: sleep product of evolution (Siegel, 2009) sleep patterns evolved to avoid predators by sleeping when predators most active 2) Restorative: sleep vital to physical health of body (Brinkman et al., 2021) replenishes chemicals & repairs cellular damage Why do we need sleep? Sleep’s functions Protects: sleep pattern suits ecological needs of each species (bat: 20hrs vs giraffe: 2hrs) Helps recuperation: restore immune system & repair brain tissue (biological makeover) Supports growth: during deep sleep, pituitary gland releases growth hormone for muscle development (↓ as we age) Brain plasticity theory: Helps us restore & rebuild fading memories of day’s experiences (consolidates & strengthens memory) Feeds creative thinking: thinking & learning boost (“why don’t you sleep on it?”) Sleep Deprivation Short-term effects: One night: ↓ attention and concentration, mental flexibility and creativity Few nights: mental & physical consequences, emotional symptoms (irritable, depressed mood) Long-term effects: Cognitive: hallucinations and delusions Emotional: mood disorders (depression, anxiety) Physiological: risk of diabetes & heart disease Sleep Deprivation Why do we need sleep? Video credit: Ted Talk – Matt Walker – A walk through the stages of sleep Common Sleep Disorders Insomnia: recurring problems falling or staying asleep Sleep Apnea: breathing periodically stops (≥10secs) causing choking or gasping Narcolepsy: irresistible and unpredictable day time attacks of sleepiness or actual sleep, lasting 5-30mins Night Terrors: high arousal & appearance of being terrified, during N3 sleep (unlike nightmares), seldom remembered REM behaviour disorder: sleepwalking; dream-enacting behaviour; physically act out vivid, often unpleasant dreams with vocal sounds and sudden, often violent arm and leg movements during REM sleep Psychoactive Drugs Substances that alter perception, mood, thinking, memory or behaviour by changing body’s biochemistry Drug classifications are based on their effects on CNS: Stimulants (amphetamines, cocaine, nicotine, caffeine) Depressants (barbiturates, benzodiazepines, alcohol) Narcotics (opioids) Hallucinogens (manufactured: LSD, PCP, MDMA – also stimulant) Marijuana (non-manufactured; cannabis) Psychoactive Drugs Psychoactive Drugs Physiology of drug effects Affect neurotransmitter levels in the brain Large amounts & frequent use can damage neurons in the brain: impair learning and memory Heavy use can lead to tolerance: increased resistance to a drug’s effects Cessation causes severe withdrawal symptoms Addiction Physical dependence: body needs drug to function; tolerance and withdrawal warning signs Psychological dependence: belief that drug needed to function Drug effects may vary depending on the person’s: previous experience with drug; physical condition; environmental setting; mental state Psychoactive Drugs – Case Examples Definitions Measuring Our Senses Sensation and Perception Sensations & Perceptions Sensation: process by which sensory receptors and nervous system receive and represent stimulus energies from our environment Perception: process of organising and interpreting sensory information In everyday experiences sensations and perceptions blend into a continuous process Sensation begins with the sense receptors: specialized forms of neurons that convert the energy of a stimulus into electrical impulses that travel along the nerves to brain Measuring the Senses Psychophysics: studies the relationships between the physical characteristics of stimuli and their effects on psychological experiences Absolute Thresholds: the minimum stimulus energy needed to consciously detect a particular stimulus 50% of the time Difference Thresholds: the minimum difference between two stimuli required for detection 50% of the time Signal Detection Theory: detection of sensory signal comprises a sensory process & a decision process, varies with motivation, alertness & expectation Sensory Adjustments Habituation: tendency of brain to stop attending to constant, unchanging information so that it can focus on what matters (e.g., A/C noise) Sensory Adaptation: diminished sensitivity of sensory receptor cells to unchanging or constant stimulus (e.g., heavily perfumed person) Sensory Deprivation: absence of normal levels of sensory stimulation, effects vary depending on duration and person’s interpretations (e.g., involuntary vs voluntary) Sensory Overload: managed by process of selective attention (focus on what’s important); may also deprive of information that is needed (e.g., texting while walking) Vision Sense organ: the eye Visual Stimulus: light waves that travel in a straight line Perceptual properties of light: Hue: dimension of visual experience specified by colour names and related to the wavelength of light Brightness: lightness; dimension of visual experience related to amount of light emitted from or reflected by an object Saturation: vividness or purity of colour; dimension of visual experience related to the complexity of light waves Visual System Light enters the visual system through the eye Psychology, 4th ed. 2015 Ciccarelli & White Visual receptors: located in retina sending signals to ganglion cells and ultimately to optic nerve Hearing Sense organ: the ear Auditory Stimulus: sound waves (air pressure changes) Perceptual properties of sound: Frequency: cycles of waves per second corresponding to experience of pitch (high, medium, low) – shorter wavelengths → more waves per second → higher frequencies Volume: intensity corresponds to experience of loudness (how soft or loud sound is) – larger wave amplitudes → louder volumes Timbre: complexity or richness in the tone of the sound – increase in number of sounds → greater richness Hearing System Hearing receptors: hair cells (topped by cilia) embedded in the basilar membrane of the organ of Corti, in the interior Outer Ear: side cochlea eardrum & canal Middle Ear: hammer, anvil & stirrup Inner Ear: cochlea Invitation to Psychology, 6th ed. 2015 Wade, Tavris & Garry The Chemical Senses: Taste Gustation: the sensation of taste (chemicals: food molecules stimulate thousands of receptors in mouth) Gustation receptors: taste buds: special kinds of neurons in mouth (primarily tongue, but also throat, inside cheeks, roof of mouth, & in gut) taste buds line walls of papillae (bumps) on tongue 4 basic tastes: salty, sour, bitter, sweet Some researchers consider 5th taste: umami (savory meaty taste, MSG); controversial as not perceptible in most foods The Chemical Senses: Smell Olfaction (olfactory sense): the ability to smell odors (chemicals: substance molecules suspended in air) Sense organ: nose Olfactory receptor cells: specialized neurons embedded in a tiny patch of mucous membrane in the upper part of nasal passage, just beneath eyes Olfactory bulbs: areas of brain located just above sinus cavity and just below frontal lobes that receive information from olfactory receptor cells The Chemical Senses: Smell Exploring Psychology, 6th ed. 2015 Myers Somesthetic Senses Somesthetic Senses: the body senses (soma: body; esthetic: feeling), comprising: – Skin senses – Proprioceptive senses – Kinesthetic sense – Vestibular senses Skin Senses: touch, pressure, temperature & pain Sensory receptors in the skin Pain is both a skin sense and an internal sense Gate control theory: experience of pain depends on whether neural impulses get past a “gate” in the spinal cord and reach the brain Somesthetic Senses Kinesthetic Sense: body’s sense of movement & position in space – Receptors located in muscles, tendons & joints (proprioceptors) Vestibular Senses: sensations of movement, balance, & body position – Sense organs: vestibular organs (otolith & semicircular organs) located in ear – Sensory conflict theory: explanation of motion sickness (information from eyes conflicts with information from vestibular senses) The Brain and the Mind – Part 1 of 2 End