Introduction to Psychology - Ch. 3 Biological Psychology PDF

Introduction to Psychology Ch. 3 Biological Psychology  Modules 3.1: Genetic and Evolutionary Perspectives on Behaviour 3.2: How the Nervous System Works: Cells and Neurotransmitters 3.3: Structure and Organization of the Nervous System 3.4: Windows to the Brain: Meas...

Introduction to Psychology Ch. 3 Biological Psychology  Modules 3.1: Genetic and Evolutionary Perspectives on Behaviour 3.2: How the Nervous System Works: Cells and Neurotransmitters 3.3: Structure and Organization of the Nervous System 3.4: Windows to the Brain: Measuring and Observing Brain Activity  3.1 Learning Objectives Know the key terminology related to genes, inheritance, and evolutionary psychology. Understand how twin and adoption studies reveal relationships between genes and behaviour. Apply your knowledge of genes and behaviour to hypothesize why a trait might be adaptive. Analyze claims that scientists have located a specific gene that controls a single trait or behaviour. Analyze explanations for cognitive gender differences that are rooted in genetics.  Historically two opposing view points: – Nativists Emphasized genes, inborn characteristics Nature – Empiricists Focused on learning and experience Nurture Human behaviour is influenced by both genetics and environment – Not nature or nurture – Genes influence the experiences one has – Experience also affect our genes (which ones are presently turned on and off) - Epigenetics  Evolutionary Psychology – A field of psychology emphasizing evolutionary mechanisms that may help to explain human commonalities in cognition, development, emotion, social practices, and other areas of behaviour Behavioural Genetics – An interdisciplinary field of study concerned with the genetic bases of individual differences in behaviour and personality  Chromosomes Chromosome & Genes – Molecule of DNA (deoxyribonucleic acid) is a molecule formed in a double-helix shape that contains four amino acids: (A)denine, (C)ytosine, (G)uanine, and (T)hymine. – Lined with all the genes a person inherits – Rod shaped – Found in nucleus of cell Genes – Located in DNA (fixed location) – Contain genetic blueprint – are the basic units of heredity; they are responsible for guiding the process of creating the proteins that make up our physical structures and regulate development and physiological processes throughout the lifespan. – Genes contain bases, carry codes for protein manufacture Heredity encoded in combinations of bases adenine, thymine, guanine, and cytosine  Chromosomes & Genes Every cell has 46 chromosomes (23 pairs) – Exception: egg and sperm Contain 23 chromosomes Combine to form new cell with 46 chromosomes Receive one of each gene pair from each parent  Chromosomes & Genes Genotype – Specific genetic makeup of an organism – Present from conception – Never changes Phenotype – Observable characteristic, including physical structures and behaviours, produced by the genetic makeup – One’s phenotype represents the physical and behavioural manifestations of the genotype through interactions with the environment. E.g., how tall you ‘can’ grow versus how tall you ‘actually’ grow  Genes So why aren’t genotype and phenotype always identical? Characteristic displayed if: – Dominant gene from either parent – Two recessive genes (one from each parent) – Polygenic transmission (multiple gene pairs influence a single phenotypic trait)  The Genetics of Difference Will now examine how differences among people may be influenced by genes  The Genetics of Difference The meaning of heritability – A statistical estimate of the proportion of the total variance in some trait that is attributable to genetic differences among individuals within a group – is a statistic, expressed as a number between zero and one that represents the degree to which genetic differences between individuals contribute to individual differences in a behaviour or trait found in a population. – Expressed as proportion (.60 or 60/100) – Maximum value is 1.0 Some variables such as height are highly heritable, other variables such as musical ability are moderately heritable  Behavioural Genetics is the study of how genes and environment influence behaviour. Study of genetic relatedness – With parents = 50% – Siblings = 50% – Grandparents = 25% Facts About Heritability 1. An estimate of heritability applies only to a particular group living in a particular environment Heritability of a particular trait may be high in one group and low in another 2. Heritability estimates do not apply to individuals, only to variations within a group Can only examine the degree to which differences among people in general are explained by their genetic differences 3. Even highly heritable traits can be modified by the environment E.g. height  Computing Heritability Studying adopted children allows researchers to compare correlations between the traits of adopted children and those of their biological and adoptive relatives Results are used to compute heritability estimate  Adoption Studies Compare an individual who was adopted earlier in life to both adopted and biological parents on a particular characteristic – If more similar to biological parents – suggests genetic influence – If more similar to adopted parents – environmental factors may be more important  Computing Heritability If identical twins are more alike than fraternal twins, then the increased similarity must be due to genetic influences But fraternal twins may receive different treatment than identical Monozygotic Dizygotic twins twins twins  Computing Heritability Investigators have also studied identical twins who were separated early in life and reared apart Any similarities in traits between them should be primarily genetic and should permit a direct estimate of heritability  Behavioural Genomics: The Molecular Approach Twin and adoption studies provide estimates of heritability, but they do not tell us how traits are inherited. To determine the “how”, researchers use behavioural genomics. – is the study of DNA and the ways in which specific genes are related to behaviour. The Human Genome Project identified between 20 000 and 25 000 genes and all the sequences of the A, C, G, and T amino acids making up the genes.  The Genetic Code Human Genome Project (1990) – Genetic structure of each of the 23 chromosome pairs has been mapped – More than 75 genes that contribute to hereditary diseases have been identified However, possession of that gene does not guarantee the disorder. – For example, a single gene has been identified as a risk factor for Alzheimer’s disease, but not everyone who inherits this gene develops the disease.  Genome Genome The full set of genes in each cell of an organism (with the exception of sperm and egg cells) The Link Between Genes and Behaviour Even when researchers locate a gene on a chromosome, they do not automatically know its role in physical or psychological functioning Most human traits are influenced by more than one gene pair – Examples include height and eye colour Combinations of genes work together to influence behaviour. Similarly, a single gene is not limited to affecting only one trait. inheritance of a gene does not guarantee that characteristic or disease. – Environmental factors can also play a role.  The Link Between Genes and Behaviour Behaviour is a result of an interaction between genetics and environment Intelligence – Is it genetics or environment? If it is completely controlled by genes – Individuals with same genes should have same IQ scores – Identical twins - correlation =.86 – Parent-child - correlation =.36 – More shared genes the more similar individuals are in IQ However, greater similarity between twins / siblings raised together than raised apart – Environment also influences IQ More important question – How do genes and environment interact to influence intelligence?  Reaction Range Help us understand interaction between genetics and environment Are there genetically determined ‘boundaries’ on the expression of a trait? Reaction range – Range of possibilities - upper and lower limits - that the genetic code allows – Individual inherits a range for potential expression of a trait – Environmental effects determine where person falls within these limits  The Genetics of Similarity Evolution Natural selection Evolutionary biologists and psychologists Innate human characteristics  Evolution & Behaviour What is evolution? – Change over time (generations) in the frequency with which genes, & the characteristics they produce, occur within an interbreeding population Why do gene frequencies in a given population change? – Mutations – Natural selection  Evolution & Behaviour Mutations and recombination – Mutations Random events and accidents in gene reproduction during cell division – Recombinations Small components of genetic material can cross over from one member of a chromosome pair to another during the formation of eggs and sperm – Create genetic variations, making evolution possible – Can be passed to offspring  Natural Selection The evolutionary process in which individuals with genetically influenced traits that are adaptive in a particular environment tend to: – survive; and – reproduce in greater numbers As a result, their traits become more common in the population Must be variation in a species’ characteristic in order for natural selection to occur Nature determines which genes survive and reproduce  Adaptations Products of natural selection Allows organisms to meet recurring environmental challenges to their survival, increasing the organisms’ reproductive ability  Types of Adaptations Broad – Learn language, reason logically, etc. Domain-specific – Solve particular problem Mate selection Choosing safe food Avoiding certain environmental hazards Etc.  Evolution Natural selection cannot explain all of the behavioural and physical traits that reflect a gene’s success E.g. why do some males birds have really bright colour while females do not – This characteristic would increase probability of being observed by a predator and decrease likelihood for survival Other causes of evolution must also occur – Sexual selection A gene’s fate is decided by members of either the other sex or the same sex, with which one is competing  Sexual selection Intersexual selection: – a member of one sex chooses a mate from the other sex on the basis of certain characteristics – E.g. females choosing males based on physical characteristics Intrasexual selection: – members of the same sex compete for a partner of the other sex Two males have to compete for attention of females – E.g. males with brighter colouring better at attracting females, females don’t need bright colour because aren’t competing  Innate Human Characteristics Because of the process of evolution that humans have undergone many characteristics are – present at birth in all humans – or develop quickly as a child matures Examples – Infant reflexes, e.g. sucking reflex – Interest in novelty – Desire to explore and manipulate objects – Impulse to play and fool around Wanting to explore and play can be adaptive – Basic cognitive skills E.g. concepts of greater than, less than, identify faces, interpret gestures and expression, etc. Thought to have helped our ancestors survive and reproduce  Human Nature More common aspects of human behaviour: – Innate ability to acquire language – Infants prewired to perceive certain stimuli, e.g. more responsive to human faces – Need to belong to a group – Some basic emotions seem universal  Evolution and Sexual Strategies Due to different kinds of survival and mating problems, the sexes have evolved differently in the areas of aggressiveness, physical dominance, and sexual strategies – Males compete with other males for access to females – Females conceive and carry only a limited number of pregnancies so they choose fewer, more dominant males with good resources and high status  Evolutionary Psychologists and the Question of Gender Focus on commonalities of human mating and dating around the world  Mate Preference What are people looking for in mates? Across cultures similarities exist in mate preference  What do men & women want in an ideal mate? For both men & women: – Mutual attraction, dependability, emotional stability – Kindness, intelligence, understanding  Attraction and Symmetry Facial symmetry is one factor involved in whether men and women perceive someone as attractive. – Humans are genetically programmed to have symmetrical features Research has shown that individuals will identify the most symmetrical faces as attractive even when the differences are so slight they cannot explain why they chose the symmetrical face over the asymmetrical. Physical characteristics often play a role is whether we approach people, want to date them, etc. – However, symmetry is likely to be less important than other qualities in the long term.  Spatial Memory Evolutionary psychologists believe that the brain has a set of cognitive adaptations for solving problems related to survival and reproductive fitness. They also believe that male and female problem solving differs because they faced different survival issues. One sex difference reported involves solving the mental rotation task. Males tend to be quicker and more accurate in solving these problems. It should be noted that females outperform males on different types of spatial tasks, specifically, tests involving memory for the spatial location of objects (see Figure 3.7). This may be due to females’ evolutionary role as a gatherer rather than as a hunter. A biological and evolutionary perspective might hypothesize that over the course of human evolution the male brain became specialized for mental rotation tasks. Spatial Memory  3.2 Learning Objectives Know the key terminology associated with nerve cells, hormones, and their functioning. Understand how nerve cells communicate. Understand the ways that drugs and other substances affect the brain. Understand the roles that hormones play in our behaviour. Apply your knowledge of neurotransmitters to form hypotheses about drug actions. Analyze the claim that we are born with all the nerve cells we will ever have.  Communication in the nervous system The structure of the neuron Neurons in the news How neurons communicate Chemical Messengers  Neurons Building blocks of the nervous system which are linked together in circuits Vary greatly in shape and size  Types of Neurons Neurons can differ in form and function. For example, motor neurons carry messages away from the brain and spinal cord and toward muscles that control their flexion and extension.  Glial Cells Support, nourish, insulate, protect neurons Surround neurons and hold them in place Manufacture nutrient chemicals neurons need Absorb toxins and waste materials that can damage neurons Guide neurons to targeted brain location during prenatal brain development Help determine which neural connection get strengthened and those that become weakened Help form the blood-brain barrier which prevents a wide range of substances, including toxins, from entering the brain Synchronize activity of billions of neurons (comprise NS) Start immune responses in the brain  Myelin Sheath Fatty insulation layer derived from glial cells – CNS – myelin derived from oligodendrocytes – insulates axon from electrical activity – acts to increase rate of transmission of signals Up to 150 m/s – nodes of Ranvier gaps that exist in myelin sheath along axon myelin is absent or very thin – signals jump from one gap to next in myelinated neurons – Some neurons are unmyelinated 0.5 to 10 m/s  Myelin Sheath Multiple sclerosis – neurological disorder characterized by demyelination of axons – immune system attacks myelin sheath – Loss of sensation – Vision problems – Jerky, uncoordinated movements and eventually paralysis  Structure of a Neuron Dendrites – receive information from other neurons and transmit towards the cell body Cell body (soma) – keeps the neuron alive and determines whether it will fire – Contains genetic information determining cell function Axon – extending fibre that conducts impulses away from the cell body and transmits to other neurons, glands or muscles – Branches at end to form a number of axon terminals  Nerves A collection of fibres from individual neurons – Typically the axons – Sometimes dendrites 43 pairs of peripheral nerves – Most enter through spine – 12 pairs directly connect to brain Cranial nerves  Past assumptions: 1. Damaged or injured neurons in CNS could not grow back (regenerate) Evidence against this assumption – Animal studies » Regrowing of severed axons in spinal cord when treated with certain nervous system chemicals 2. No new neurons in CNS were produced after birth in mammals Research with mice – New neurons were created from immature cells from mouse brains » Referred to as neurogenesis  Neurogenesis – The production of new neurons from immature stem cells Stem cells – Immature cells that renew themselves and have the potential to develop into mature cells – These cells exist in the human brain and other organs  Stem-Cell Research Embryonic stem cells appear most promising in developing treatments for cancers, organ and brain diseases (e.g., Alzheimer’s) Currently have ethical debate over their use – Stems cells gotten from aborted fetuses or from embryos consisting of a few cells New techniques try to extract them without harming the embryo McGill team has had some success in transforming adult cells into brain tissue Have reprogrammed adult cells (e.g. skin cells) into stem cells (induced pluripotent stem cells) – 2007 – 2012 Noble Prize winners for medicine – http://news.ca.msn.com/world/nobel-awarded-for-stem-cell- early-cloning-work How Neurons Communicate: An Electrochemical Process Neurons: – Generate electricity – Release chemicals Cell membrane of neurons acts as selective filter allowing some substances to enter and leave the neuron and preventing other substances from doing so How Neurons Communicate: An Electrochemical Process Neurons – have a resting potential of -70 millivolts – creating a state of polarization – surrounded by a salty liquid environment which has a high concentration of sodium ions (Na+) – inside has some positively charged potassium ions (K+) and many other negatively charged ions – inside of cell more negative than outside of cell – combination creates the resting potential  Action Potential Electrical part of electrochemical process is the Action Potential Sudden reversal in the membrane’s voltage Depolarization = Shift in voltage from minus to plus Resting = minus 70 mV (inside cell) Shift to plus 40 mV (inside cell)  Action Potential Dendrites - stimulated by axons of other neurons and cause a small shift in the cell membrane’s electrical potential Graded potential – a change in electrical potential of a neuron that is proportional to the intensity of the incoming stimulation, but not sufficient to produce an action potential If graded potential (partial depolarization) reaches -55 mV (action potential threshold), neuron fires and an action potential occurs Action potential threshold – intensity of stimulation needed to produce an action potential  Action Potential Unlike graded potentials, which vary in proportion to the intensity of the stimulation, action potentials occur with maximum intensity or they do not occur at all – this is referred to as the all-or-none law  Action Potential The membrane potential is changed by graded potentials acting on ion channels which are small protein structures in cell membrane Each ion channels allows specific ions to enter or leave the neuron When the action potential threshold is reached ion channels are opened and Na+ ions flow into neuron – making membrane voltage more positive (depolarization) When there is complete depolarization +40 mV this constitutes the action potential  Action Potential Na+ ion channels stay open for short period of time K+ channels are opened and K+ leaves the neuron in order to return the neuron to resting state, -70 mV inside the cell The action potential appears to flow along the membrane, however, there is not a single action potential, a new one is generated at each section of the cell membrane – In myelinated axons, action potential hops from one Node of Ranvier to the next After the action potential – K+ ions pumped back into the neuron and – Na+ pumped back to the outside of the cell – to restore the original balance of ions so that another action potential can occur  Action Potential After the action potential there occurs a refractory period – A time period where the membrane is not excitable and another action potential cannot be discharged – This limits the rate at which action potentials can occur within a cell Action potentials are identical to one another – Thus information about the strength of the stimulus can be communicated by increasing the rate of firing or by increasing the number of neurons that are firing Resting Potential to Action Potential Communication Between Neurons Synaptic Transmission Synapse – Comprised of Axon terminal, The synaptic cleft, Membrane of dendrite or cell body Neurons do NOT make physical contact Communicate via chemicals called neurotransmitters Synaptic cleft – Gap between axon terminal & dendrite  Communication Between Neurons Chemical part of electrochemical process Neurotransmitters – Chemicals produced by neurons – Synthesized inside neuron – Stored in synaptic vesicles – Released by presynaptic neuron Bind to receptor sites in postsynaptic neuron – Specific neurotransmitters bind only to specific sites! – Cause a chemical reaction to occur that will either excite or inhibit the postsynaptic neuron Numerous types of neurotransmitters have been identified, each with its own unique shape. – However, neurons tend to only send and receive a limited number of neurotransmitters. Synaptic Transmission  Effect of Neurotransmitters Excitatory neurotransmitter – Depolarizes neuron’s membrane – Stimulates inflow of sodium ions – Increases likelihood of action potential Inhibitory neurotransmitter – Hyperpolarizes neuron’s membrane – Stimulates ion channels to allow K+ to flow out – Decreases likelihood of action potential – Allows fine-tuning of responses Prevents uncoordinated discharges (e.g., seizures) Deactivation of Neurotransmitters Neurotransmitters activate or inhibit neuron until deactivated Two major ways: – Breakdown Other chemicals in the synapse break down neurotransmitters into their chemical components – Reuptake Neurotransmitters are taken back into presynaptic axon terminal  How neurons communicate The message that reaches a final destination depends on: – Rate at which individual neurons are firing – How many are firing – What types of neurons are firing – Where the neurons are located – Degree of synchrony among different neurons Transmission of messages doesn’t depend on how strongly individual neurons are firing – Firing of neuron is all-or-none  Chemical Messengers Neurotransmitters Endorphins Hormones (Endocrine System)  Neurotransmitter (NT) Chemical substance released by a transmitting neuron at the synapse and capable of affecting the activity of a receiving neuron Abnormal levels can have negative effects – However abnormal levels do not necessarily cause the disorder  Major Neurotransmitters Serotonin – Influences neurons involved in appetite, sleep, sensory perception, temperature regulation, pain suppression, aggression, and mood – Undersupply associated with Depression Sleeping disorders Eating disorders Dopamine – Voluntary movement, attention, emotion, reward – Undersupply Parkinson’s Depression – Oversupply schizophrenia  Major Neurotransmitters Acetylcholine (ACh) – Muscle action, memory, attention, cognitive functioning – Junction between neurons and skeletal muscles Voluntary movement – Undersupply Related to memory loss in Alzheimer’s Norepinephrine – Increased heart rate, slowing of intestinal activity during stress, learning, memory, dreaming, emotion, waking, attention – Regulating stress response – Undersupply depression  Major Neurotransmitters Gamma amino butyric acid (GABA) – Major inhibitory NT, important in controlling all behaviour – Abnormal levels implicated in: Sleeping disorders Eating disorders Convulsive disorders, e.g. epilepsy – Destruction of GABA-producing neurons in Huntington’s Tremors Loss of motor control Glutamate – Major excitatory NT – Ability to form new memories – Abnormal functioning – trigger of epileptic seizure  Types of Neurotransmitters Table 3.1 Major Neurotransmitters and Their Functions Neurotransmitter Some Major Functions Glutamate Excites nervous system; memory and autonomic nervous system reactions GABA (gamma-amino butyric acid) Inhibits brain activity; lowers arousal, anxiety, and excitation; facilitates sleep Acetylcholine Movement; attention Dopamine Control of movement; reward-seeking behaviour; cognition and attention Norepinephrine Memory; attention to new or important stimuli; regulation of sleep and mood Serotonin Regulation of sleep, appetite, mood  Drug Effects on Neurotransmission Agonists - are drugs that enhance or mimic the effects of a neurotransmitter’s action. Antagonists - inhibit neurotransmitter activity by blocking receptors or preventing synthesis of the neurotransmitter.  Endorphins Also known as endogenous opioid peptides Effects – Reduce pain – Promote pleasure Thought to play role in – Appetite, sexual activity, blood pressure, mood, memory, learning Some functions as neurotransmitters, same as hormones Others modulate the effects of neurotransmitters Were discovered because morphine an opiate was discovered to bind to opiate receptor sites in the brain Endocrine System Consists of numerous glands throughout body Conveys information from one part of the body to another in form of hormones Interacts with nervous system & immune system  Endocrine System Hormones – chemical messengers that are secreted from its glands into the bloodstream Many cells have receptors that respond to specific hormones Hormones – Promote bodily growth – Aid in digestion – Regulate metabolism – Sexual development and behaviour – Etc.  Endocrine System Some neurotransmitters are also classified as hormones – E.g. norepinephrine  Endocrine System Examples of hormones: – Melatonin Secreted by pineal gland Regulates biological rhythms Promotes sleep – Adrenal hormones Produced by adrenal glands Involved in emotion and stress Mobilizes body’s resources Also increase in response to – Heat, pain, cold, burns, physical exercise, etc. Prolonged exposure can have detrimental effects E.g.s – Cortisol – increases blood sugar levels, boosts energy – Epinephrine (adrenalin) – norepinephrine  Endocrine System Examples of hormones: Sex hormones – Regulates development and functioning of reproductive organs – 3 main types Androgens – E.g. testosterone – Masculinizing hormones – Produced mainly in testes, but also in adrenal glands and ovaries – Start the physical changes males go through at puberty – Hair growth in both sexes  Endocrine System Examples of hormones: Sex hormones – 3 main types Estrogens – Feminizing hormones – Start physical changes in females at puberty – Influence course of menstrual cycle – Produced mainly in ovaries, also in testes and adrenal glands Progesterone – Contributes to growth and maintenance of uterine lining – Produced mainly in ovaries, also in testes and adrenal glands  Endocrine versus Nervous System Nervous system Endocrine system – Transmits – Transmits information information rapidly slower, because – Uses nerve impulses depends on rate of to transmit blood flow information – Uses hormones via the – Communicates with a smaller number of bloodstream to cells transmit information – Communicates with larger number of cells  3.3 Learning Objectives Know the key terminology associated with the structure and organization of the nervous system. Understand how studies of split-brain patients reveal the workings of the brain. Apply your knowledge of brain regions to predict which abilities might be affected when a specific area is injured or diseased.  Nervous System  Composed of neurons  It gathers and processes information, produces responses to stimuli, and coordinates the workings of different cells  Its processes underlie thoughts, feelings, and behaviour Divisions of the Nervous System  Divisions of Nervous System 1. Central Nervous System (CNS) – Brain and Spinal Cord – Receives, processes, interprets, and stores incoming sensory information – Sends out messages destined for glands, internal organs and muscles 2. Peripheral Nervous System – Connects CNS with muscles, glands, and sensory receptors – Subdivided into: Somatic nervous system Autonomic nervous system  The Central Nervous System Spinal cord – A collection of neurons and supportive tissue running from the base of the brain down the centre of the back – Protected by spinal column  Central Nervous System: Spinal cord Spinal Cord – Most nerves enter / leave CNS through spinal cord – Motor neurons exit front of spinal cord and sensory neurons enter back of spinal cord – Spinal reflexes do not involve brain Though there can be connections to the brain, so can sometimes be influenced by emotion, etc. Structure – Central portion = grey neuron cell bodies – Outer portion = white myelinated axons  Central Nervous System: Brain Brain – 3 pounds – 2% of body weight – 20% of oxygen Metabolic rate – Remains relatively constant day / night – Increases slightly when dreaming Number of structures controlling behaviour – both voluntary & involuntary 2 Hemispheres (left & right)  Peripheral Nervous System Contains all components of nervous systems outside of brain and spinal cord  Peripheral Nervous System Types of nerves: 1. Sensory - Carry input messages from special receptors in muscles, skin, other internal and external sense organs to spinal cord and then passed onto brain 2. Motor - Transmit impulses from brain & spinal cord to glands, muscles, & organs  Peripheral Nervous System Subdivided into: 1. Somatic nervous system (skeletal NS) – Consists of sensory & motor neurons – Sends information from sensory organs to CNS – Sends information from CNS to muscles to control voluntary movements 2. Autonomic nervous system (2 divisions) – Controls glands, blood vessel, & smooth muscles in body organs – Controls involuntary movements/functions i. Sympathetic nervous system: arouses body ‘fight or flight’ ii. Parasympathetic nervous system: slows down body processes  The Brain and Its Structures Table 3.2 Major Brain Regions, Structures, and Their Functions Regions and Structures Functions Hindbrain Blank Brainstem (medulla and pons) Breathing, heart rate, sleep, and wakefulness Cerebellum Balance, coordination and timing of movements; attention and emotion Midbrain Blank Superior colliculus Orienting visual attention Inferior colliculus Orienting auditory attention Forebrain Blank Basal ganglia Movement, reward processing Amygdala Emotion Hippocampus Memory Hypothalamus Temperature regulation, motivation (hunger, thirst, sex) Thalamus Sensory relay station Cerebral Cortex Blank Occipital lobe Visual processing Parietal lobe Sensory processing, bodily awareness Temporal lobe Hearing, object recognition, language, emotion Frontal lobe Thought, planning, language, movement  The Hindbrain The hindbrain controls the basic, life-sustaining processes The brain stem is located at the top of the spinal cord. consists of the medulla and the pons. Nerve cells in the medulla connect with the body to perform basic functions, such as breathing and heart rate. The pons contributes to general levels of wakefulness and play a role in dreaming.  The Hindbrain The reticular formation sends signals to the cortex to influence attention and alertness and also communicates with cells in the spinal cord involved with motor control. The cerebellum is specialized in the coordination and timing of movements. is the lobe-like structure at the base of the brain that is involved in the monitoring of movement, maintaining balance, attention, and emotional responses. Involved in remembering simple skills and acquired reflexes Plays a part in higher cognitive tasks as well: analyzing sensory information solving problems understanding words  The Midbrain Midbrain - resides just above the hindbrain and primarily functions as a relay station between the sensory and motor areas. The midbrain is involved with the reflexive ability to identify the location of sudden movements and sounds. The ability to capture your visual attention is influenced by the superior colliculus. The ability to move your auditory attention is influenced by another midbrain structure, the inferior colliculus.  The Forebrain Forebrain the most visibly obvious region of the whole brain, consists of multiple interconnected structures that are critical to such complex processes as emotion, memory, thinking, and reasoning. Major structures include: basal ganglia, limbic system, hypothalamus, Thalamus Cerebral cortex  The Forebrain Basal Ganglia - are involved in facilitating planned movements and skill learning, and integrating sensory and movement information with the brain’s reward system. The basal ganglia are involved with planned movement, skill learning, and pleasurable emotions. the nucleus accumbens is a part of the basal ganglia that accompanies all sorts of pleasurable experiences, such as sexual excitement, thrills (from gambling), and satisfying a food craving. Addicting drugs, such as cocaine, target dopamine transmission in the nucleus accumbens.  The Forebrain Limbic System is an integrated network involved in emotion and memory.  The Forebrain Limbic System Structures: Amygdala facilitates memory formation for emotional events, mediates fear responses, and appears to play a role in recognizing and interpreting emotional stimuli, including facial expressions. The amygdala connects with structures in the nervous system responsible for adaptive fear responses, such as freezing in position when a threat is detected. Hippocampus is critical for learning and memory, particularly the formation of new memories. enabling us to form spatial memories for navigating the environment Hypothalamus serves as a sort of thermostat, maintaining body temperature and it also affects drives (e.g., aggression and sex) by interacting with the endocrine system. Regulates autonomic nervous system  The Forebrain Thalamus Relays sensory messages to the cerebral cortex – Routes sensory information to appropriate place (e.g., visual goes to visual centres; auditory to auditory centres) Includes all sensory messages except those from sense of smell  The Cerebral Cortex Cerebral Cortex is the convoluted, wrinkled outer layer of the brain that is involved in multiple higher functions, such as thought, language, and personality  The Cerebral Cortex Largest brain structure This upper part of the brain is divided into two cerebral hemispheres – connected by the corpus callosum is a densely concentrated bundle of nerve cells connecting the two hemispheres. – Generally Left hemisphere controls right side of body Right hemisphere controls left side of body – Two hemispheres involved in different tasks Referred to as lateralization In charge of most sensory, motor and cognitive processes  Cerebral Cortex Cell bodies in cortex form a grey tissue (grey matter) 75% of area lies within fissures (folds) – great amount of tissue compressed into a small space – Provide landmarks for dividing cortex into major areas – 4 lobes Each lobe has a particular set of functions, but are also connected by nerve cells to each other and other regions of the midbrain and hindbrain Lobes of the Cerebral Cortex  Lobes of the Cerebral Cortex Occipital lobes – Contains visual cortex – processing of visual information Parietal lobes – are located behind the frontal lobes, are involved in our experiences of touch as well as bodily awareness. – Parts of these lobes involved in attention and a variety of mental operations – Contains somatosensory cortex  Parietal Lobe Somatosensory Cortex – Receives specific sense information from opposite side of body – Receives sensory information that gives rise to the sensations of cold, heat, touch, sense of balance, and sense of body movement  Motor & Somatosensory Cortex Amount of cortex devoted to body part proportional to sensitivity of that part – Governs opposite side of body  Lobes of the Cerebral Cortex Temporal lobes – Memory, perception, emotion – involved in hearing, language, and some higher-level aspects of vision such as object and face recognition. – Contains auditory cortex Processes sounds – Left lobe, Wernicke’s area Involved in language comprehension  Frontal lobes 29% of the human cortex Self-awareness; planning; initiative; responsibility; emotional experience; creative thinking; social judgment allow you to deliberately guide and reflect on your own thought processes. Damage – loss in ability to plan and carry out a sequence of actions, and loss in ability to judge the order in which a series of events took place Prefrontal cortex – Located just behind forehead – Seat of executive functions – Goal-setting; judgment; strategic planning; impulse control – Involved in personality  Frontal Lobes Left lobe, Broca’s area – Language production – Important for ability to perform sequence of fine motor movements required for speech – Involved in the ability to use grammar Motor Cortex – Controls movement on opposite side of body – Controls movement of over 600 muscles involved in voluntary movement – Located at rear of frontal lobe  Hemispheric Specialization The two hemispheres of the brain may look the same, but perform different functions, a phenomenon called hemispheric specialization. i) Basically, the right side specializes in cognitive tasks that involve visual and spatial skills, recognition of visual stimuli, and musical processing. ii) The left hemisphere is more specialized for language and math.  Hemispheric Specialization Research on split-brain patients shows us: – Nearly all right-handed and the majority of left-handed individuals process language mainly in the left hemisphere – Left side more involved in some symbolic, logical, and sequential tasks – Many researchers believe in left-hemisphere dominance Left hemisphere exerts control of right hemisphere – Others insist the right-hemisphere is not inferior It is superior in – spatial visual problem-solving (e.g. map reading), – Facial recognition – Read facial expressions Involved in comprehending non-verbal sounds Has some language abilities Shouldn’t think of the two hemispheres as two minds as the two halves co-operate on many tasks  The Corpus Callosum Millions of myelinated axons connecting the brain’s hemispheres Provides a pathway for communication between hemispheres If surgically severed to treat epilepsy, hemispheres cannot communicate directly  Split Brain Experiments Sever corpus callosum hemispheres no longer communicate - but optic nerve remains intact With optic nerve – Fibers cross over (optic chiasm) Right visual field - processed in left hemisphere Left visual field - processed in right hemisphere Word presented to right visual field – could verbally describe what they saw Word presented to left visual field – could not verbally describe what they saw  Split-Brain Experiment Subjects were presented information to one or the other side of their brain E.g. presented photographs with two different faces pasted together – Presented images quickly – half of image presented to left visual field and half presented to right visual field – Person had to: Say what they had seen Point with left had to face they had seen Split-Brain Experiment  Split-Brain Experiment Results – Patients identified verbally the pictures to the right (i.e., boy) Speech centers are typically in the left hemisphere which receives input from the right visual field – When asked to point to the face seen, the patients pointed to the left picture (I.e. man with moustache) Left hand controlled by right hemisphere which gets input from the left visual field – Didn’t notice anything different about the original photographs they viewed Split-Brain Experiment  3.4 Learning Objectives Know the key terminology associated with measuring and observing brain activity. Understand how studies of animals with brain lesions can inform us about the workings of the brain. Apply your knowledge of neuroimaging techniques to see which ones would be most useful in answering a specific research question. Analyze whether neuroimaging can be used to diagnose brain injuries.  Studying the Brain Methods: 1. Neuropsychological Test 2. Destruction & Stimulation 3. Electrical and Magnetic Detection 4. Scanning the brain  Studying the Brain Neuropsychological Tests – Measure verbal & nonverbal behaviours known to be affected by certain types of brain damage – Used to evaluate individuals who have had damage to their brain due to accident or disease Destruction & Stimulation – Damage specific areas of the brain through use of chemical, cold, heat, or electricity and observe the effects of creating this damage (lesion method) – Surgically remove certain areas of the brain and examine effects – Stimulate areas with electricity / chemicals and observe the effects on behaviour  Studying the Brain Transcranial magnetic stimulation (TMS) can impair brain activity only temporarily and can be safely applied to humans. – is a procedure in which an electromagnetic pulse is delivered to a targeted region of the brain. – This pulse interacts with the flow of ions around the neurons of the affected area. The result is a temporary disruption of brain activity. TMS can also be used to stimulate, rather than temporarily impair, a brain region. Has been used to stimulate under-active areas of the brain associated with depression. Has been used to stimulating nerve cells that were impaired by stroke related damage.  Structural Neuroimaging is a type of brain scanning that produces images of the different structures of the brain. – Computerized tomography (CT scans) – Magnetic Resonance Imaging (MRI) – Diffusion tensor imaging is a form of structural neuroimaging allowing researchers or medical personnel to measure white-matter pathways in the brain.  Scanning the Brain CT scans – Computerized axial tomography – Use X-rays to take pictures of narrow slices of brain – Brain image then re- constructed – Locating areas of damage within the brain can help us learn about the relationship between brain damages and psychological functioning  Scanning the Brain MRI – Magnetic resonance imaging Magnetic fields and radio frequencies used to produce vibrations in nuclei of water atoms Vibrations picked up by special receivers Can study brain structure Takes pictures several minutes a part  Functional Neuroimaging A type of brain scanning that scanning that provides information about which areas of the brain are active when a person performs a certain task – Electroencephalogram (EEG) – Magnetoencephalography (MEG) Measures the tiny magnetic fields created by the electrical activity of nerve cells in the brain - few ms after it occurs – Positron Emission Tomography (PET) – Functional magnetic resonance imaging (fMRI)  Electrical Detection EEG - electroencephalography Records electrical activity of thousands of neurons through electrodes Some EEG patterns correspond to wakefulness & sleep Use EEG to examine changes in brain activity when a particular event occurs, such as the presentation of a stimulus – Show how long it takes the brain to process stimuli – Can’t show structures, anatomy, or functional regions of the brain  Electrical Detection Needle electrodes – Can be inserted into an exposed brain or through holes in skull – Allows for gathering of more precise information – Can stimulate the brain or record activity  Scanning the Brain PET scans – Positron emission tomography A method for analyzing biochemical activity in the brain, using injections of a glucose-like substance containing a radioactive element Areas of the brain that are activated during a task will have higher glucose concentrations and will show up on the scan  Scanning the Brain PET Scan  Functional MRI measures brain activity by detecting the influx of oxygen-rich blood into neural areas that were just active. detects increased blood flow to active areas, and displays structure and function – can capture images in as little as 30 ms  Studying the Brain - evaluation Brain-scan images can sometimes convey oversimplified and misleading impressions – E.g. Manipulating color scales in PET scan can emphasize a small contrast between two brains or minimize large contrast – Although researchers have shown that the activity that we see in fMRI images is actually linked to the firing of neurons, we still need to be cautious when interpreting fMRI data. One reason is that it is correlational in nature. just because a brain area is active while we perform a task does not mean that it is necessary for that task – Brain scans don’t indicate what is happening in the brain (mentally or physically) Indicate where things are occurring - not how or why