Psychology 1010.06M A Biologically-Oriented Introduction to Psychology Instructor: Professor Jennifer Steeves 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? e-mail: [email protected] telephone: 416-736-2100 X20452 Web: www.yorku.ca/steeves/1010M_2009 Review from Last Class Genetic Explanations of Behavior – Alcoholism • twin studies • adoption studies • artificial selection studies Evolutionary Explanations of Behavior – ultimate vs. proximate causes – altruism • • • • cooperation vs. altruism kin selection theory selfish genes? reciprocal altruism 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 Sample Question According to kin selection theory, animals that engage in altruistic acts, such as warning others of an approaching predator, are: a) actually benefiting themselves as individuals b) not actually reducing their own chances of survival and reproduction c) helping to ensure the survival of the genes they have in common with close relatives d) expecting other animals to return the favour at some future time 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. 1 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. The Brain: Source of Mind and Self 1. The Nervous System a. b. c. 2. ~3 lbs ~2% of body weight 20% of body’s oxygen consumption Peripheral nervous system Central nervous system Hierarchical Brain: structures and functions Neural Bases of Behaviour a. b. c. 3. Human Brain Neurons Electrochemical process Synaptic transmission How we can study the brain Show video P&B CNS vs. PNS Spinal Cord Brain Nerves Central Nervous System • brain + spinal cord Peripheral Nervous System • nerves connecting CNS to muscles and organs Peripheral Nervous System Peripheral Nervous System Skeletal (Somatic) Autonomic Sympathetic Parasympathetic 2 Somatic System Reflexes • 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 Peripheral Nervous System Autonomic Nervous System Peripheral Nervous System Skeletal (Somatic) Autonomic Sympathetic Parasympathetic The Sympathetic Nervous System in Action Sympathetic • “fight or flight” Parasympathetic • “rest and digest” Central Nervous System Spinal Cord Brain • brain • spinal cord Nerves 3 Spinal Cord Brain Spinal injuries • input can’t get in • output can’t get out • different levels wired to different body parts – quadraplegic vs. paraplegic Brain Stem and Thalamus Brainstem and Midbrain • postural reflexes • vital reflexes (breathing rate, heart rate) • movements • sleep & arousal Thalamus Cerebellum • relay or gateway or “traffic officer” • sensory messages directed to higher centres (except olfaction) • “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 4 Basal ganglia Limbic system • amygdala – emotion • hippocampus – memory formation • hypothalamus – – – – – – • movement • Parkinson’s disease affects BG circuits – tremor – rigidity – problems initiating movements regulate body functions autonomic NS hormones drives emotion “4 Fs” • pituitary gland – receives messages from hypothalamus – Then sends hormones to endocrine glands Fig 5.7 Cerebral Cortex Localization of Function Phrenology -bumps on the head said to be related to personality traits • cortex = bark = outer surface of brain Localization of Function The Case of Phineas Gage “Dr. Penfield, I smell toast!” • • • • Wilder Penfield, Montreal Neurological Institute Epilepsy surgery Stimulate brain can invoke movements, sensations, emotions, memories, experiences 5 Each hemisphere is divided into 4 lobes Occipital Lobe Frontal Parietal Occipital • Input from eyes via optic nerve • Contains primary visual cortex • Outputs to parietal and temporal lobes Occipital Lobe Primary Visual Cortex Temporal Parietal Lobe Temporal Lobe • Inputs from multiple senses • 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 Somatosensory Cortex Parietal Lobe • Output to frontal lobe • Sensorimotor control – hand-eye coordination – eye movements – attention • Outputs to limbic system, basal ganglia, and brainstem Frontal Lobe • No direct sensory input • Includes motor cortex • Includes motor speech area (Broca’s area) • Important for planning and sequencing ideas – Input from touch to somatosensory cortex – Input from vision via occipital lobe and audition via temporal lobe Brain has 2 Hemispheres Frontal Lobe Broca’s Area Motor Cortex 6 Sensory Information sent to opposite hemisphere 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 • 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!!! Corpus Callosum Somatosensory Cortex 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 • 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 7 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 Glia support cells – provide insulation • increase speed of neurons – provide nutrients – keep toxic substances out (blood-brain barrier) – support neurons – clean-up and repair 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) 8 Axons Structure indicates function Let’s take a closer look at what goes on in the axons… sensory neurons cortex cerebellum – relay information – not many dendrites interneurons – collect and integrate information motor neurons – collect information – long axons Ion Distribution-- resting potential Let’s Zoom in on an Axon 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? • 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 Membrane Potential (mV) • By storing up energy, you can use it later • Analogy: water dam +50 Resting Potential 0 Resting membrane potential -70 Time  9 Hyperpolarization +50 Membrane Potential (mV) Membrane Potential (mV) +50 0 -70 Depolarization 0 -70 Time  Time  The Action Potential Membrane Potential (mV) +50 Threshold of excitation Na+ channels close K+ channels open Na+ enters cell K+ leaves cell 0 Larger depolarization Hyperpolarization -60 -70 Nothing happens At threshold, Small Voltage-gated depolarization Na+ channels open below threshold The cell won’t produce another action potential until the resting potential has been restored. This is called the cell’s refractory period. Resting membrane potential restored How is a Neuron Like a Toilet? • threshold • all-or-none • 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 10 Rapid Action Potentials • An action potential takes less than 1/1000 second Action Potential Propagates = depolarization (+) • 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 potentials on their own are quite slow and metabolically expensive Go Faster! 1. Wider diameter axons – the squid’s solution -- giant axons (1 mm diameter) What can make them go faster? Yeah, that’s fine if you’re a squid and don’t have a lot of neurons! 2. Saltatory conduction Saltatory Conduction Action Potential Propagates = depolarization (+) ~30 metres/sec ~120 metres/sec 11 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 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 Multiple Sclerosis • decay of myelin sheaths • impaired sensation and movement • axons are exposed and break down • sclerosis = hardening • may be an autoimmune disorder Yes, you CAN learn to think better, stronger and FASTER! 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” 12 Synapses Postsynaptic Potentials = the connection between the axon of one neuron and (usually) the dendrite of another • Postsynaptic – on the dendrites (or sometimes the cell body) of the receiving neuron • Potential – voltage difference • Excitatory post-synaptic potentials (EPSPs) – “yes” votes presynaptic membrane • Inhibitory post-synaptic potentials (IPSPs) – “no” votes synaptic cleft postsynaptic membrane What happens when the action potential reaches the end? Synapses presynaptic membrane synaptic cleft postsynaptic membrane Receptors: “Lock and Key” neurotransmitter molecules Synaptic Transmission precursor 1 SYNTHESIS breakdown product transmitter DEGRADATION STORAGE synaptic vesicles INACTIVATION breakdown product 2 7 5 REUPTAKE 6 RELEASE 3 4 RECEPTOR BINDING PSPs 13 Receptor binding Drug Actions • opens ion channels • 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 Acetylcholine (ACh) Drugs • neurotransmitter in the PNS (neuromuscular junction) and CNS that involved in motor control, learning and memory, and sleep and dreaming Antagonist Agonist 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!) 14 What can you do with a neuron? 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 • Perform computations • Make muscles twitch • Make glands squirt 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 EEG (electroencephalography) • Measure voltage differences with electrodes placed on the scalp • “Like holding a microphone over a stadium” Example: Head direction neuron in limbic system EEG (electroencephalography) Waveforms vary with brain states Event-related Potentials (ERPs) Epileptic seizure 15 Neuropsychological Patients MRI vs. fMRI • Determine the performance deficits of patients who have lesions (brain damage) to a specific part of the brain • Examples MRI studies brain anatomy. Functional MRI (fMRI) studies brain function. – Phineas Gage – Broca’s aphasia – split brain patients Functional MRI Brain Imaging: Anatomy CAT Photography PET MRI Big magnet (typical magnet is 60,000X earth’s magnetic field) + radio waves MRI vs. fMRI good resolution (1 mm) MRI PET and fMRI Activation 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 16 Transcranial Magnetic Stimulation (TMS) • Virtual, temporary lesions • Wire coil on head-- magnetic pulse-- causes neurons to fire • Video clip 17