Biologisk psykologi & neuropsykologi

Transcription

1 Biologisk psykologi & neuropsykologi 1

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3 Galen Claudius Galenus of Pergamum( AD), better known as Galen, was an ancient Greek physician. His views dominated European medicine for over a thousand years. Brain not the heart site of the soul Two basic questions The fundamental organ the brain The fundamental unit and it s mode of operation the neuron 3

4 BOLD activation depicting true vs. false memories The relation between brain structure and function (a) 4

5 The relation between brain structure and function (b) Source: Carlson, N.R., Physiology of Behavior (6th edition), p Boston: Allyn & Bacon, Allyn & Bacon. Reproduced with permission. 5

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7 Sagittal views of the human brain (a) Source: Reprinted from England, M.A. and Wakely, J. (1991) A Colour Atlas of the Brain and Spinal Cord, p , by permission of the publisher Mosby. 7

8 Sagittal views of the human brain (b) Source: Reprinted from England, M.A. and Wakely, J. (1991) A Colour Atlas of the Brain and Spinal Cord, p , by permission of the publisher Mosby. 8

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21 Neural Bases of Behavior Neurons: Basic building blocks of the nervous system Functions: Generate electrical activity, communicate with muscles, glands, other neurons Neural Bases of Behavior Cell body (soma): Contains structures needed to keep neuron alive Dendrites: Collect messages from other neurons, send to cell body Axon: Conducts electrical impulses to neurons, muscles, glands 21

22 Neural Bases of Behavior Resting potential of cell = -70 millivolts Action potential: When electrically stimulated, interior voltage shifts to +40 millivolts Neural Bases of Behavior Creating the action potential Electrical stimulus stimulates opening of sodium (Na+) channels, creating depolarization 22

23 Neural Bases of Behavior Restoring the resting potential Cell closes Na+ channels; potassium ions (K+) flow out; Na+ ions are pumped out Absolute refractory period (cannot discharge impulse) Neural Bases of Behavior All-or-none law Action potentials occur at a uniform and maximum intensity, or they do not occur at all 23

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26 Neural Bases of Behavior The Myelin Sheath Insulates the axon Commonly found in higher animals Multiple sclerosis: damage to the myelin sheath Neural Bases of Behavior Two types of signal transduction Electrical Chemical 26

27 Neural Bases of Behavior Synaptic Transmission Stages Synthesis Storage Release Binding Deactivation Neural Bases of Behavior 27

28 Neural Bases of Behavior Synthesis Neurotransmitters formed inside the neuron Neural Bases of Behavior Storage Neurotransmitters stored in synaptic vesicles Chambers located in the axon terminals 28

29 Neural Bases of Behavior Release Action potential leads to movement of vesicles to axon terminal surface and release of neurotransmitters Neural Bases of Behavior Binding Neurotransmitters bind themselves to receptor sites on receiving neuron s membrane 29

30 Neural Bases of Behavior Excitatory neurotransmitters: create a graded or action potential Inhibitory neurotransmitters: prevents the postsynaptic neuron from firing an action potential Effects of Drugs Agonists Enhance a neuron s ability to synthesize, store, release neurotransmitters Bind with and stimulate postynaptic receptor sites Increase difficulty for neurotransmitters to be deactivated 30

31 Effects of Drugs Antagonists Reduce neuron s ability to synthesize, store, or release neurotransmitters Prevent neurotransmitter from binding with postsynaptic neuron Neural Bases of Behavior Deactivation Occurs in two major ways Breakdown into chemical components Reuptake into presynaptic axon terminal 31

32 Neural Bases of Behavior Specialized transmitter systems Acetylcholine (ACh) Involved in memory and muscle activity 32

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36 Neural Bases of Behavior Specialized transmitter systems Neuromodulators (e.g. endorphins) Modulate the sensitivity of neurons to their specific transmitters 36

37 Effects of Drugs Agonists: Drugs that increase neurotransmitter activity Antagonists: Drugs that inhibit or decrease neurotransmitter activity Effects of Drugs Alcohol: depressant; agonist and antagonist Caffeine: stimulant; agonist for adenosine Nicotine: agonist for acetylcholine 37

38 Effects of Drugs Amphetamines: stimulants; increase activity of dopamine and norepinephrine Cocaine: blocks reuptake of dopamine and norepinephrine The Parietal and Occipital Lobes Thomas Karlsson 38

39 Lateral view of the brain showing the major sulci and gyri in the parietal lobe. Post CG, postcentral gyrus; SPL, superior parietal lobule; SMG, supramarginal gyrus; AG, angular gyrus. (From N. Gluhbegovic and T. H. Williams: The Human Brain: A Photographic Guide. Harper & Row, 1980, courtesy of the authors.) 39

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43 Standard Clinical Tests for Demonstrating the Presence of Unilateral Neglect Line Bisection: The patient is given a single horizontal straight line and asked to put a mark at the very center of the line. A patient with left neglect will make this mark a long way to the right of the true center of the line, thus: Correct bisection: Patient's bisection: x x

44 Line cancellation: The patient is given a sheet of paper covered with small, short straight lines and is asked to cross out every line. A person with left neglect will cross out the lines on the right half of the page but ignore the lines on the left. Example: Copying an object or scene: The person is asked to copy a scene exactly as it appears. A person with left neglect will omit details on the left side of the page when re-copying it. Example: The upper panel is the scene the person is asked to copy. The lower panel is the person s attempt at copying this scene. 44

45 Drawing or describing objects or scenes from memory: The person will neglect the left side of an object when it is being drawn from memory Example: Writing The patient is asked to write anything that crosses their mind in regular lined paper. A person with left neglect will use only the extreme right-hand side of the page when writing text. Example: 45

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53 The frontostriatothalamic systems Thomas Karlsson, Linköping University 53

54 The Nervous System Motor cortex Controls 600 or more muscles in involuntary body movements The Nervous System The Frontal Lobes 29% of cortex in humans (much more than in other animals) Involved in self-awareness, planning, initiative, responsibility, emotional experience 54

55 The Nervous System The Frontal Lobes Prefrontal cortex Seat of executive functions (e.g. goal setting, planning, impulse control) Two examples of sorting behavior on the Wisconsin Card Sorting Test (WCST). 55

56 Two examples of the environmental dependency syndrome exhibited by patients with frontal damage when they visited their physician s home Source: From Human Autonomy and the Frontal Lobes: Part II. Patient Behavior in Complex and Social Situations. The Environmental Dependency Syndrome by F. Lhermitte, Annals of Neurology, 19(4), pp. 339, 340. Copyright 1986 by the American Neurological Association. Used with permission of Lippincott-Raven Publishers, Philadelphia, PA. An example of the format of the recency judgment task. 56

57 An example of correct performance on a sixitem selfordered pointing task. An example of three problems in the Tower of London task. 57

58 The role of different brain regions in response inhibition Source: (A) From Liddle et al., 2001, p. 106, fig. 1; (B, C), From Konishi et al., 1999, p. 985, figs. 3b, 3c. Activation of dorsolateral prefrontal cortex when an individual must impose and maintain an attentional set Source: From Banich et al., 2000, p. 990, fig. 1a. 58

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60 Different medial pf sites Anterior: intention Posterior: execution 60

61 Motor Circuit SMA Oculomotor Circuit Frontal Eye Fields Dorsolateral Prefrontal Cortical Circuit DLPFC Lateral Orbitofrontal Cortical Circuit LOFC Anterior Cingulate Circuit AC Other cortical input Other cortical input Other cortical input Other cortical input Other cortical input Putamen Caudate Caudate Caudate Ventral Striatum Gpi SNr Gpi SNr Gpi SNr Gpi SNr Gpi SNr Thalamus Thalamus Thalamus Thalamus Thalamus 61

62 From Stuss & Levine, Ann Rev Psychol,

63 Is there an additional, sixth system? Nature Neuroscience, 5, ,

64 Evolution A three-year-old girl, belonging to the species Australopithecus afarensis, who lived in Ethiopia 3.3 million years ago. 64

65 Evolutionary Psychology Problem of adaptation to environments Result = evolved psychological mechanisms and behavioral strategies

66 Evolutionary Psychology What is evolution? Change over time in frequency with which genes, and characteristics they produce, occur within an interbreeding population Evolutionary Psychology Mutations Create genetic variations, making evolution possible Can be passed to offspring

67 Evolutionary Psychology Principle of Natural Selection (Darwin) Characteristics more likely to be preserved if they: 1) increase the likelihood of survival 2) increase the ability to reproduce Evolutionary Psychology Adaptation Products of natural selection Allows organisms to meet environmental challenges to their survival

68 Evolutionary Psychology Examples of human adaptations Bipedal locomotion Development of tools, weapons Social organization (hunting in groups) Change in brain structures

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70 Human Timeline Praeanthropus walked fully upright Early hominids had the distinct human pelvis for upright walking. Fossil trackways also demonstrate full bipedality. 70

71 The Timetable of Human Evolution Some important dates: Chimp-human split: 6-8 million years ago First fossil hominids: ~ 4-5 million years ago (e.g., Lucy (Australopithecus afarensis; 4 mya Homo habilis ( Handyman ): 2 million years ago Homo erectus ( Peking/Java Man ): 1 million years ago The Timetable of Human Evolution Modern Homo sapiens: 200,000 70,000 years ago Exit from Africa and divergence: 100,000 50,000 years ago Agricultural revolution:10,000 years ago 71

72 Australopithecus Homo erectus Neandertal Homo sapiens Figure 6.15 Hominid Evolution 72

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74 Evolutionary Psychology Caveats Role of culture in behavior? Acknowledgement of roles of both remote and proximate (near-term) causes of behavior

75 Genetic Influences on Behavior Genotype = genetic makeup of the individual Phenotype = individual s observable characteristics Genetic Influences on Behavior Chromosome = Doublestranded, coiled molecule of deoxyribonucleic acid (DNA)

76 3-170 Genetic Influences on Behavior Heredity encoded in combinations of bases adenine, thymine, guanine, and cytosine Genes contain bases, carry codes for protein manufacture

77 Genetic Influences on Behavior Characteristic displayed if: Dominant genes from both parents Two recessive genes Polygenic transmission (multiple gene pairs influence phenotype) Genetic Influences on Behavior Human Genome Project Genome consists of 35,000 genes Gene interactions are more complex than previously believed

78 Genetic Influences on Behavior Field of behavior genetics Study of how heredity and environment interact to influence psychological characteristics Genetic Influences on Behavior Concordance Co-occurrence of a trait in people who are closely related

79 Genetic Influences on Behavior Adoption Studies Early adoptees are compared with both biological and adoptive parents More similar to biological = strong influence of genes Genetic Influences on Behavior Twin studies Compare concordance rates for monozygotic (identical) and dizygotic (fraternal) twins If MZ twins are very alike and more so than DZ twins, genetic factors are likely

80 Genetic Influences on Behavior Heritability coefficient Estimates the extent to which variation in a group can be attributed to genetic factors Genetic Influences on Behavior Gene Manipulation Recombinant DNA procedures Enzymes cut DNA, combined with DNA from other organism, inserted into host organism