Psychology 1010 6.0 Section A Instructor: Professor Jennifer Steeves e-mail: [email protected] telephone: 416-736-2100 X20452 Web: www.psych.yorku.ca/kopinska Contact by email for appointment Frequently asked questions • Class is full, still try to enroll • Can you post the slides because I can’t take notes and listen… or I missed the last class… • Am I responsible for the text, the lectures, and the videos that you show in class? • Don’t understand the assignment • Where is the assignment posted? Sample Question factual: A negative correlation means that: a) high values of one variable are associated with low values of the other. b) high values of one variable are associated with high values of the other. c) low values of one variable are associated with low values of the other. d) there is no relationship between the two variables. e) none of the above 1 Sample Question conceptual: It is quite likely that the more classes students miss, the lower their test grades tend to be. This relationship illustrates a(n): a) negative correlation b) positive correlation c) coefficient of correlation. d) zero correlation. e) a perfect positive correlation. Sample question applied: Julie has found that the number of hours she sleeps each night is related to the scores she receives on quizzes the next day. As her sleep approaches eight hours, her quiz scores improve; as her sleep drops to five hours, her quiz scores show a similar decline. Julie realizes that: a) there is a negative correlation between the number of hours she sleeps and her quiz grades. b) there is a positive correlation between the number of hours she sleeps and her quiz grades. c) her low quiz scores are caused by sleep deprivation the night before a quiz. d) she should sleep about ten hours a night to ensure 100 percent quiz grades. e) high quiz scores are due to adequate sleep the previous night. 2 The Brain: Source of Mind and Self 1. The Nervous System a. b. c. 2. Neural Bases of Behaviour a. b. c. 3. Peripheral nervous system Central nervous system Hierarchical Brain: structures and functions Neurons Electrochemical process Synaptic transmission How we can study the brain Show video P&B Human Brain ~3 lbs ~2% of body weight 20% of body’s oxygen consumption CNS vs. PNS Spinal Cord Brain Nerves Central Nervous System • brain + spinal cord Peripheral Nervous System • nerves connecting CNS to muscles and organs 3 Peripheral Nervous System Peripheral Nervous System Skeletal (Somatic) Autonomic Sympathetic Parasympathetic Somatic System • Sensory Neurons – input from body to CNS • Motor neurons – output from CNS to control muscle movements • Interneurons – sensory-motor relay within CNS • Both voluntary and reflex movements • Spinal reflex arc Reflexes 4 Peripheral Nervous System Peripheral Nervous System Skeletal (Somatic) Autonomic Sympathetic Parasympathetic Autonomic Nervous System The Sympathetic Nervous System in Action Sympathetic • “fight or flight” Parasympathetic • “rest and digest” 5 Central Nervous System Spinal Cord • brain • spinal cord Brain Nerves Spinal Cord Spinal injuries • input can’t get in • output can’t get out • different levels wired to different body parts – quadraplegic vs. paraplegic Brain 6 Brain Stem and Thalamus Brainstem and Midbrain • postural reflexes • vital reflexes (breathing rate, heart rate) • movements • sleep & arousal Thalamus • relay or gateway or “traffic officer” • sensory messages directed to higher centres (except olfaction) 7 Cerebellum • “little brain” • traditionally thought to help you “walk and chew gum at the same time (balance and muscle coordination) • scientists now realize it’s much more diverse and sophisticated-- involved in higher cognitive tasks Basal ganglia • movement • Parkinson’s disease affects BG circuits – tremor – rigidity – problems initiating movements Fig 5.7 Limbic system • amygdala – emotion • hippocampus – memory formation • hypothalamus – – – – – – regulate body functions autonomic NS hormones drives emotion “4 Fs” • pituitary gland – receives messages from hypothalamus – Then sends hormones to endocrine glands 8 Cerebral Cortex • cortex = bark = outer surface of brain Localization of Function Phrenology -bumps on the head said to be related to personality traits Localization of Function The Case of Phineas Gage 9 “Dr. Penfield, I smell toast!” • • • • Wilder Penfield, Montreal Neurological Institute Epilepsy surgery Stimulate brain can invoke movements, sensations, emotions, memories, experiences Each hemisphere is divided into 4 lobes Frontal Parietal Occipital Temporal Occipital Lobe • Input from eyes via optic nerve • Contains primary visual cortex • Outputs to parietal and temporal lobes Occipital Lobe Primary Visual Cortex 10 Temporal Lobe • Auditory cortex gets input from the ears • Visual Input from occipital lobe • Recognition and Memory – – – – Auditory Cortex speech recognition face recognition word recognition memory formation Temporal Lobe • Outputs to limbic system, basal ganglia, and brainstem Parietal Lobe • Inputs from multiple senses Somatosensory Cortex – Input from touch to somatosensory cortex – Input from vision via occipital lobe and audition via temporal lobe Parietal Lobe • Output to frontal lobe • Sensorimotor control – hand-eye coordination – eye movements – attention Frontal Lobe • No direct sensory input • Includes motor cortex • Includes motor speech area (Broca’s area) • Important for planning and sequencing ideas Frontal Lobe Broca’s Area Motor Cortex 11 Brain has 2 Hemispheres Sensory Information sent to opposite hemisphere • Sensory data crosses over in pathways leading to the cortex • Visual crossover – left visual field to right hemisphere – right field to left • Other senses similar The visual fields NOT the eyes cross over!!! Contralateral Motor Control • Movements controlled Motor Cortex by motor area • Right hemisphere controls left side of body • Left hemisphere controls right side • Motor nerves cross sides in spinal cord Somatosensory Cortex 12 Corpus Callosum • Major ( but not only) Medial surface of right hemisphere pathway between sides • Connects comparable structures on each side • Permits data received on one side to be processed in both hemispheres • Aids motor coordination Corpus Callosum of left and right side Corpus Callosum • What happens when the corpus callosum is cut? • Sensory inputs are still crossed • Motor outputs are still crossed • Hemispheres can’t exchange data • Scientific American video The ‘Split Brain’ studies • Special apparatus – picture input to just one side of brain – screen blocks objects on table from view Verbal left hemisphere Nonverbal right hemisphere 13 Cell types in the brain 1) Glia – – – – “glue” support cells constantly replacing themselves ~1 trillion glial (1,000,000,000,000) cells 2) Neurons – information processing cells – less able than other cells to replace themselves – ~100 billion (100,000,000,000) neurons 14 Glia support cells – provide insulation • increase speed of neurons – provide nutrients – keep toxic substances out (blood-brain barrier) – support neurons – clean-up and repair 15 Information Flow dendrites – many dendrites per neuron (“dendritic tree”) – collect information from other neurons cell body – one cell body per neuron – normal cell regulation functions – axon hillock sums inputs axon – one axon per neuron – transmit signal • can be over long distances (e.g., sensory neurons in toe) – end feet (axon terminals) communicate information to the dendrites of other neurons (synapses -- stay tuned) Structure indicates function sensory neurons cortex – relay information – not many dendrites cerebellum interneurons – collect and integrate information motor neurons – collect information – long axons Axons Let’s take a closer look at what goes on in the axons… 16 Let’s Zoom in on an Axon Ion Distribution-- resting potential Outside Membrane Inside + - + - + - + - + - + - + - + - + - • Because of the A- inside and Na+ outside, there is a voltage across the membrane • Inside is 70 mV more negative than outside • Resting voltage = -70 mV So What? • By storing up energy, you can use it later • Analogy: water dam • When nerve cell is stimulated → sudden inflow of + charged Na+ across membrane followed by outflow of K+ • → brief change in electrical voltage • → The action potential 17 Membrane Potential (mV) +50 Resting Potential 0 Resting membrane potential -70 Time  Membrane Potential (mV) +50 Hyperpolarization 0 -70 Time  Membrane Potential (mV) +50 Depolarization 0 -70 Time  18 The Action Potential Membrane Potential (mV) +50 Threshold of excitation Na+ enters cell Na+ channels close K+ channels open K+ leaves cell 0 Larger depolarization Hyperpolarization -60 -70 Nothing happens At threshold, Small Voltage-gated depolarization Na+ channels open below threshold Resting membrane potential restored The cell won’t produce another action potential until the resting potential has been restored. This is called the cell’s refractory period. An action potential either occurs or it doesn’t ... and if it occurs, it occurs at full amplitude. This is called the All-or-none Law 19 How is a Neuron Like a Toilet? • threshold • all-or-none • refractory period Rapid Action Potentials • An action potential takes less than 1/1000 second • You can have many action potentials in a row – sometimes we’ll call action potentials “spikes” – sometimes we describe an AP as the neuron “firing” Action Potential Propagates = depolarization (+) 20 Action potentials on their own are quite slow and metabolically expensive What can make them go faster? Go Faster! 1. Wider diameter axons – the squid’s solution -- giant axons (1 mm diameter) Yeah, that’s fine if you’re a squid and don’t have a lot of neurons! 2. Saltatory conduction Saltatory Conduction = depolarization (+) 21 Action Potential Propagates ~30 metres/sec ~120 metres/sec How Does Saltatory Conduction Work? • Glia wrap around axon • This insulation is called myelin • Nodes of Ranvier – Gaps between glia • Saltatory conduction – Action potential jumps between nodes Myelin • Myelin is mostly fat • Fat is white • White matter contains myelinated axons gray matter • dendrites, cell bodies, end feet white matter • axons 22 Myelinization • not all neurons are covered in myelin at birth • myelin develops in different regions at different times • simpler areas (sensory and motor) become myelinated first • myelination can continue until ~age 20 in areas involved in abstract thinking Yes, you CAN learn to think better, stronger and FASTER! Multiple Sclerosis • decay of myelin sheaths • impaired sensation and movement • axons are exposed and break down • sclerosis = hardening • may be an autoimmune disorder What makes an action potential begin? Axon hillock • “little hill” at the junction of the cell body and the beginning of the axon • gathers information from dendrites • sort of like a “vote counter” 23 Synapses = the connection between the axon of one neuron and (usually) the dendrite of another presynaptic membrane synaptic cleft postsynaptic membrane Postsynaptic Potentials • Postsynaptic – on the dendrites (or sometimes the cell body) of the receiving neuron • Potential – voltage difference • Excitatory post-synaptic potentials (EPSPs) – “yes” votes • Inhibitory post-synaptic potentials (IPSPs) – “no” votes 24 What happens when the action potential reaches the end? Synapses presynaptic membrane synaptic cleft postsynaptic membrane neurotransmitter molecules synaptic vesicles Receptors: “Lock and Key” 25 Synaptic Transmission precursor 1 SYNTHESIS breakdown product transmitter DEGRADATION STORAGE INACTIVATION breakdown product 2 7 5 REUPTAKE 6 RELEASE 4 3 RECEPTOR BINDING PSPs Receptor binding • opens ion channels Drug Actions • Drugs can act at any stage of synaptic transmission • Agonists – drugs that increase the effectiveness of synaptic transmission • Antagonists – drugs that decrease the effectiveness of Normal Antagonist Agonist 26 Acetylcholine (ACh) Drugs • neurotransmitter in the PNS (neuromuscular junction) and CNS that involved in motor control, learning and memory, and sleep and dreaming Serotonin • serotonin – neurotransmitter involved in emotions and dreaming • depression – common disorder • 5% of population depressed at any one time • 30% depressed at some point during lifetime • higher incidence among women than men – seems to be due to reduced serotonin • selective serotonin reuptake inhibitors (SSRIs) – e.g., Prozac, Paxil, Zoloft, – selective for serotonin – reuptake inhibitors prevent serotonin from being taken back up so it remains in the synaptic cleft longer Brief Overview of Neurotransmitters NEUROTRANSMITTER FUNCTIONS DISEASES DRUGS Acetylcholine Motor control over muscles Learning, memory, sleeping & dreaming Alzheimer’s () Nicotine () many toxins (e.g., spider venom ) Norepinephrine Arousal and vigilance, eating behavior Dopamine Reward and motivation, Motor control over voluntary movement Schizophrenia () Parkinson’s () L-dopa for Parkinson’s () Amphetamine () Cocaine () Antipsychotics () Serotonin Emotional states and impulsiveness, dreaming Depression (), mania ( ) Prozac and other SSRIs () Ecstasy () LSD () Psilocybin (mushroom) () GABA Inhibition of action potentials; anxiety and intoxication Glutamate Enhances action potentials, learning and memory Adenosine relaxation (sympathetic parasympathetic return) Endorphins Pain reduction, reward Amphetamine () Valium () Barbiturates (“downers”) () Alcohol () Caffeine () Heroin Morphine Jogging Chocolate Substance P Pain perception Chili peppers Anandamide Enhancing forgetting? THC (marijuana) Chocolate (a lot!) 27 What can you do with a neuron? • Perform computations • Make muscles twitch • Make glands squirt Neural Computing 1,000 to 10,000 synapses per neuron ~3 neurotransmitters/neuron (range ~2-5) 4 neurotransmitters x 3 states = 81 states ~100 billion (100,000,000,000) neurons 28 Single-Neuron Recording • Stick a thin electrode into an animal’s brain (rat, cat, monkey) • record action potentials from a single neuron • measure neuronal firing under a range of conditions Example: Head direction neuron in limbic system EEG (electroencephalography) • Measure voltage differences with electrodes placed on the scalp • “Like holding a microphone over a stadium” EEG (electroencephalography) Waveforms vary with brain states Epileptic seizure 29 Event-related Potentials (ERPs) Neuropsychological Patients • Determine the performance deficits of patients who have lesions (brain damage) to a specific part of the brain • Examples – Phineas Gage – Broca’s aphasia – split brain patients MRI vs. fMRI MRI studies brain anatomy. Functional MRI (fMRI) studies brain function. 30 Brain Imaging: Anatomy CAT Photography PET MRI Functional MRI Big magnet (typical magnet is 60,000X earth’s magnetic field) + radio waves MRI vs. fMRI good resolution (1 mm) MRI fMRI poorer resolution (~3 mm but can be better) one image … many images (e.g., every 2 sec for 5 mins) ↑ neural activity  ↑ blood oxygen  ↑ fMRI signal 31 PET and fMRI Activation Transcranial Magnetic Stimulation (TMS) • Virtual, temporary lesions • Wire coil on head-- magnetic pulse-- causes neurons to fire • Video clip How can genetics and evolutionary theory explain behavior? • Evolutionary psychology: – Field of psychology emphasizing evolutionary mechanisms that may help explain human commonalities in cognition, development, emotion, social practices, etc… • Behavioural genetics: – Interdisciplinary field of study concerned with the genetic bases of individual differences in behaviour 32 Unlocking the Secrets of Genes • Genes and how they operate – Chromosomes • rod-shaped structures within cells that carry genes – Genes • functional units of heredity which are composed of DNA and specify the structure of proteins – DNA • transfers genetic characteristics by way of coded instructions for the structure of proteins – genome How can genetics and evolutionary theory explain behaviour? A. Genetics of Alcoholism B. Genetics of Intelligence C. Evolutionary Psychology of Altruism How can we examine genetic factors in behaviour? 1) Twin studies Identical Twins • monozygotic (MZ): originate from one zygote (fertilized cell) • 100% relatedness Fraternal Twins • dizygotic (DZ): originate from two separate zygotes • 50% relatedness (same as any two siblings) 33 Logic of Twin Studies • Both identical and fraternal twins share the same environment (same age, same parents) • Only MZ twins share exactly the same genes • Concordance: both twins share the same trait • Discordance: one twin has a trait that the other doesn’t • When we observe a trait exhibiting high concordance for MZ but not DZ twins, we can conclude the trait is strongly affected by genetics Comparison of Concordance Rates Between MZ & DZ Twins TRAIT MZ (%) DZ (%) Blood type 100 66 Eye color 99 28 Mental retardation 97 37 Measles 95 87 Idiopathic epilepsy 72 15 Schizophrenia 69 10 Diabetes 65 18 Identical allergy 59 5 Tuberculosis 57 23 A) Genetics of Alcoholism Concordance rates for alcoholism • 77% MZ vs. 54% DZ for males (significant) • 39% MZ vs. 42% DZ for females (notsignificant) Concordance rates for drinking patterns (frequency and amount) • greater for MZ than DZ • less severe drinking patterns are less heritable, and more severe drinking patterns are more heritable 34 How can we study genetic factors in behaviour? 2) Adoption Studies • Examine whether adopted children bear a greater resemblance to their biological parents and siblings or their adoptive parents and siblings • Can suggest whether genes or environment (nature vs. nurture, nativism vs. empiricism) play a greater role Adoption Studies of Alcoholism • First-degree relatives of alcoholics are three to four times more likely to have alcoholism than first-degree relatives of non-alcoholics – ~ 20-25% of sons and brothers of alcoholics become alcoholic, and 5% of the daughters and sisters • But how can you tell if it’s genes or environment? • Sons of alcoholic biological parents were more likely to become alcoholics than sons of non-alcoholic biological parents, even when they were reared by non-alcoholic adoptive parents. Same is true for females How can we study genetic factors in behaviour? 3) Artificial Selection Studies • Specific strains of animals (usually rats) are bred for a particular trait • Strength of that trait is measured over successive generations 35 Artificial Selection Studies of Alcoholism • breed strain of rats for alcohol preference – one strain voluntarily drinks alcohol, prefers alcohol to other liquids, works hard to obtain alcohol and develops a physical dependency – other strain does not show these characteristics • the chemical composition of specific brain mechanisms in these two strains is different, suggesting a biological susceptibility to alcoholism Summary Many experimental approaches show a genetic influence on alcoholism • twin studies • adoption studies • artificial selection studies Does this mean that if your father is an alcoholic, you will necessarily be one too? B) Genes and Individual differences • Twin studies also show a role of genetics in psychological traits such as intelligence 36 Genes and Group Differences • Tomato plant experiment The Environment and Intelligence • • • • Poor prenatal care Malnutrition Exposure to toxins Stressful family circumstances Artificial Selection for Intelligence Tyron (1942) • “maze-bright”: mate male and female rats who made the fewest mistakes in mazerunning • “maze-dull”: mate male and female rates who made the most mistakes in mazerunning • difference cumulates over successive generations 37 Conclusion • Feature such as intelligence seem to be heritable Evolution Charles Darwin 1809-1882 Darwin provided biology with its great unifying principle: “The Theory of Natural Selection” 38 Evolution Pre-Darwinian views Doctrine of Progression The world is full of as many diverse forms as it can be. Each species exists because of a special creation by God. One species could not be derived from another. Each species is a pre-ordained type. Variation is due to error, in some cases pathology. But how does one explain fossils and other apparently extinct species? World cataclysms -- like the Great Flood. 39 The continuity of existing forms -- from inanimate to animate, from plants to animals was part of the Grand Ascending Chain of Progression. The top of the Chain was Western European Man. An obvious ally in this view was the Christian Church. Evolutionists The French naturalist, JeanBaptiste Lamarck (1744-1829), introduced the idea of the inheritance of acquired characteristics. -- environmental effects on organ development -- use and disuse leads to change -- changes in form through conscious will -- movement toward perfection Darwin advocated the idea of Natural Selection Darwin’s father, Robert Darwin, was a successful country physician In 1825 at age 16, Darwin was sent off to Edinburgh to study medicine, but he hated it. 40 Captain Robert Fitzroy 1805-1865 Darwin spent from 1831 to 1837 on the Beagle visiting Cape Verde Islands, Brazil, Montevideo, Tierra del Fuego, Buenos Aires, Valparaiso, Chile, the Galapagos, Tahiti, New Zealand, and Tasmania. Darwin was impressed with fossils in Patagonia. He was also impressed with the diversity of life in the Galapagos Islands. ...the different species of giant tortoises on the different islands of the Galapagos. Darwin was also struck by the fact that there were 14 different species of finches, each of which had a beak shape and size that was adapted to its particular ecological niche. He collected all kinds of specimens, which Fitzroy described as “cargoes of apparent rubbish.” 41 After Darwin returned to England, he befriended Sir Charles Lyell, the geologist, and in 1839 married his cousin, Emma Wedgewood. He became secretary of the Geological Society and began to write a series of impressive works in biology and geology. He did not publish his developing ideas on natural selection until 1859. Alfred Russel Wallace 1823-1913 Darwin was prompted in part by a letter he received from Alfred Russel Wallace in 1858 in which Wallace outlined a similar set of ideas. They published a short paper together in 1858 and then Darwin, urged by his colleagues, published “The Origin of Species” in 1859. All 1500 copies sold out on the first day! “Descended from the apes! My dear, we hope it is not true. But if it is, let us pray that it may not become generally known.” 42 But what is the Theory of Natural Selection? Three Inductions and two Deductions Induction 1: Organisms have an enormous capacity to overproduce. Induction 2: Populations (with a few exceptions) remain remarkably stable. Deduction 1: There is a struggle for survival. Induction 3: Individuals differ in their characteristics and many of these differences are heritable. Deduction 2: Those individuals who possess adaptive characteristics will reproduce more successfully than those who don’t and will pass on these characteristics to their offspring. Deduction 2: Those individuals who possess adaptive characteristics will reproduce more successfully than those who don’t and will pass on these characteristics to their offspring. This last process is what Darwin meant by ‘Natural Selection’. Evolution can be seen as the accumulation of the changes in the population due to natural selection. 43 C) Evolutionary Theory NeoDarwinian Theory (natural selection coupled with modern genetics) provides a wonderful framework for understanding the ultimate causes of behaviour Ultimate causes: “why” questions Proximate causes: “how” questions The Puzzle of Altruism “Why be nice (especially when it costs you)?” • Cooperative traits: good for both self and neighbours • Altruistic traits: good for neighbours, bad for self • Darwinian theory does NOT predict altruism • Darwin himself was puzzled by altruism Some ground-nesting birds, such as the Killdeer, use a “broken-wing display” to lead a potential predator away from the nest. Killdeer Charadrius vociferus 44 Ground squirrels, for example, give alarm calls when they spot a predator. This will happen even when they don’t have offspring. Golden-mantled ground squirrel The other squirrels in the area then run for their burrows and hide. Moreover, the ground squirrels who give alarm calls are often stalked and eaten by predators like owls and badgers. Why would they put themselves at risk? What do they get out of doing this? Kin Selection Theory “I would gladly lay down my life for two brothers or eight cousins.” -- J.B.S. Haldane, English biologist They are helping to ensure that their young survive -- and since they share 50% of their genes in common with their offspring, this means that they are projecting their own genes into the next generation. One can see how this behaviour would be selected. 45 Generationn Genes for broken-wing display X Generationn+1 XXX XX In other words, one can see how the behaviour will increase an individual’s fitness -- the success that the individual has in increasing its genetic representation in subsequent generations. But not all behaviour will increase individual fitness. The Selfish Gene “A chicken is just an egg's way of making more eggs.” Key Concept: Evolution acts on the gene rather than the individual or the species. Controversial among evolutionary biologists 46 The idea of kin selection can help explain some otherwise puzzling phenomena. Consider the case of Belding’s Ground Squirrel, for example. Female Belding’s Ground squirrels are three times more likely to give alarm calls than male Belding’s Ground Squirrels. Belding’s Ground Squirrel Why? Kin selection helps explain why. Females on average migrate 50 m from the burrow in which they were born. Males on average migrate 400 m. Male Female 47 Thus, if a female gives an alarm call, she is much more likely to be warning a relative than a male would if he gives an alarm call. Notice that kin selection does not require that the individuals know that they are warning their relatives. Reciprocal Altruism Is it possible for altruistic behaviour to occur among unrelated individuals? The answer is yes. Natural selection could favor altruistic acts between unrelated individuals if the individual performing the act at a reproductive cost to itself received repayment at a later time from the individual it helped. In a sense, reciprocal altruism is like Aesop’s fable about Androcles and the Lion. The idea is also captured in common phrases such as “You scratch my back and I’ll scratch yours!” Reciprocal altruism is extremely common in human beings. Although it is far less common in other animals, it does occur. 48 Male baboons will form alliances where one baboon will engage an alpha male in a fight while the other copulates with the alpha male’s female consort. On a later occasion they will reverse their roles. There is a real risk for the individual who engages the alpha male in a fight. Clearly then, there must be some payback later. In other words, reciprocity must occur. Reciprocal altruism will emerge more often in species where there is: • Individual recognition • Long-lived individuals • Stable communities • Well-developed memory 49 Kin selection and reciprocal altruism can reinforce one another. Thus, altruistic behaviour is likely to be more common in small towns than in large urban centres. Where is human evolution going? • What traits does the current environment select for? • Are we still subject to selection? • Designer babies 50