Neuroscience and Behavior

1. Neuroscience and Behavior Chapter 2

2. Introduction • Biological psychology: scientific study of biological bases of beh and mental processes • AKA  biopsychology, psychobiology • Part of neuroscience (scientific study of nervous system • What we will study • Neuron • Nervous Systemand its divisions

3. Next major subtopic • Neurons – we will study… • Parts of the neuron • Communication of neural impulse within neuron • Communication of neural impulse between neurons

4. Neurons—Introduction • Neuron: highly specialized cell that communicates info in electrical & chemical form • Types • Sensory neurons: convey info about environment from sense organs TO brain • Motor neurons: convey info TO muscles and glands • Interneurons: communicate btn neurons

5. Neurons—Parts • Dendrites: fibers extending from cell body that receive information • Cell body (soma): processes nutrients and provides cell with energy • Axon: long, fluid-filled tubes that carry neuron’s message to other cells • Vary in length • Myelin sheath: white, fatty covering of axon that aids speed of impulse • Multiple Sclerosis results in damage to myelin  faulty neural communication • Video clip: http://www.youtube.com/watch?v=i-NgGKSNiNw&NR=1&feature=fvwp

6. Neurons—Parts

7. Neurons—Communication WITHIN Neuron • What happens? • Neuron fires and sends electrical impulse from the dendrite through the cell body to axon • After it fires, there is brief resting period during which neuron cannot re-fire

8. Neurons—Communication WITHIN Neuron (cont’d) • Terms: • Action potential: neural impulse; brief electrical impulse that is transmitted along axon • Stimulus threshold: minimum level of stimulation required to activate neuron/action potential • All-or-none law: principle that neuron is sufficiently stimulated or not (neuron fires same each time) • Refractory period: period after action potential when neuron cannot fire again

9. Neurons—Communication BETWEEN neurons • Synapse: connection btn axon of sending neuron and dendrite of receiving neuron • Synaptic gap/cleft: fluid-filled space btn axon terminal of one neuron and dendrite of another neuron

10. Neurons—Communication BETWEEN neurons (cont’d) • Communication across neurons occurs chemically (most often) • Presynaptic neuron creates chemical that crosses synaptic gap to postsynaptic neuron • Neurotransmitter: chemical that transmits message across synaptic gap • 100 different compounds • Lock and key – there are receptor sites on dendrites • Video: Zoloft commercial • Reuptake: process by which neuron’s axon terminal reabsorbs neurotransmitter • Types of messages: Excitatory and inhibitory messages (of neurotransmitter) • Excitatory message: increases likelihood that postsynaptic neuron will activate • Inhibitory message: decreases likelihood that postsynaptic neuron will activate

11. Neurons—Communication BETWEEN neurons (cont’d) • Neurotransmitters • Acetylcholine • Stimulates muscles to contract • Also involved in memory, learning, and intellectual functioning • For those with Alzheimer’s Disease  severe deficit in acetylcholine • Dopamine • Involved in movement, attn, learning, and pleasurable/rewarding sensations • Parkinson’s Disease  too little; Schizophrenia  too much

12. Neurons—Communication BETWEEN neurons (cont’d) • Neurotransmitters (cont’d) • Serotonin and norepinephrine • Serotonin  sleep, mood and emotion • Norepinephrine  activation of neurons in brain, learning and memory • Endorphins • Regulate pain reception • Drugs and neurotransmitters • May increase/decrease amt of neurotransmitter • Affect length of time neurotransmitter spends in synapse • Mimic neurotransmitter • Block affect of neurotransmitter

13. Next major topic: Nervous system • We will study… • The major divisions of the nervous system (CNS and peripheral nervous system) • The brain, the lobes of the brain, and hemispheric specialization

14. New Major Topic—Nervous System • Nervous system divided into two parts—Central Nervous System and Peripheral Nervous System • Central Nervous System: brain and spinal cord • Peripheral Nervous System: all nerves outside of CNS

15. Nervous System—Peripheral Nervous System • Peripheral Nervous System: all neurons outside of CNS • Two components: • Somatic Nervous System  • Voluntary movement • Skeletal muscles • Autonomic Nervous System  involuntary movement • Think automatic • Includes blood pressure, heart rate, breathing and digestion • Two branches—Sympathetic and Parasympathetic • Sympathetic Nervous System: increases energy – arousal • Body’s emergency system • Fight-or-flight response  HR increases, digestion stops, breathing increases • Parasympathetic Nervous System: conserves energy – calming • Returns body to resting state

16. Nervous System—Peripheral Nervous System • Autonomic Nervous System (cont’d) • Two branches—Sympathetic and Parasympathetic • Sympathetic Nervous System: increases energy – arousal • Body’s emergency system • Fight-or-flight response  HR increases, digestion stops, breathing increases • Parasympathetic Nervous System: conserves energy • calming • Returns body to resting state

17. Nervous System—Central Nervous System • CNS = Brain and spinal cord • Spinal cord: connects Peripheral Nervous System to brain • Spinal reflex: simple automatic beh processed in spinal cord • Example  withdrawal reflex from heat, pain, etc. • Single sensory neuron and single motor neuron

18. Nervous System—Central Nervous System (cont’d) • Brain • Development—highlights • Neural tube lined with neural stem cells • These develop into 3 structures – hindbrain, midbrain, and forebrain • As neural tube expands, it develops cavities called ventricles that are found at core of developed brain • New neurons developed at rate of 250,000 per minute at peak periods of development • Fetal brain continues to dev  as many as 2 million synaptic connections per second • At birth, brain is about one-fourth size of adult brain • Fully matured brain weights about 3 lbs • Recent research indicates brain cont’s to grow into early adulthood (frontal lobe)

19. Nervous System—Central Nervous System (cont’d) • Brain • Neuroimaging Techniques • Electroencephalogram (EEG): amplified reading of electrical activity of brain • PET scan (Positron Emission Tomography): displays activity of various brain areas • MRI (Magnetic Resonance Imaging): uses magnetic fields and radio waves to produce computer-generated images of brain tissue • fMRI (Functional MRI): reveals blood flow and therefore brain activity

20. Nervous System—Central Nervous System (cont’d) • Brain (cont’d) • Brainstem – Hindbrain and Midbrain • Hindbrain • Connects spinal cord to brain • Sensory and motor neurons cross one side of body to opp side of brain  why left side of body is controlled by right side of brain (called contralateral organization) • Structures of hindbrain – medulla, pons, and cerebellum • Medulla: controls breathing, HR, digestion (vital functions) • Pons: bridge btn cerebellum and rest of brain • Cerebellum: balance, muscle tone, coordinated movements, motor skills • Reticular formation (aka reticular activating system): network of neurons that regulates attn, arousal, and sleep • Midbrain: relay station for processing auditory and visual information

21. Nervous System—Central Nervous System (cont’d)

22. Nervous System—Central Nervous System (cont’d) • Brain (cont’d) • Forebrain—cerebrum • 90% of brain • Cerebral cortex: • Thin layer of interconnected neurons • Divided into two hemispheres and four lobes • Temporal Lobe • Occipital Lobe • Parietal Lobe • Frontal Lobe

23. Nervous System—Central Nervous System (cont’d) • Brain (cont’d) • Lobes • Temporal lobe • Located near temple • Auditory information • Occipital Lobe • Back of brain • Visual information • Parietal Lobe • Bodily or somatosensory info (touch, pressure, info from muscles) • Body parts are represented on somatosensory cortex but not equally distributed (in proportion to sensitivity to stimulation, so hands and face are largest) • Frontal Lobe • Planning, initiating, and executing voluntary movement • Also contains primary motor cortex which controls body parts (similar to somatosensory cortex above) • Brain anatomy – http://www.pbs.org/wnet/brain/3d/index.html

24. Nervous System—Central Nervous System (cont’d) • Brain (cont’d) • Association areas of cortex • In all four lobes • Combine sensory and motor information • Coordinate interaction among diff brain areas

25. Nervous System—Central Nervous System (cont’d) • Brain (cont’d) • Limbic system • Other forebrain structures beneath cortex • Form border around brainstem • Involved in emotion, motivation, learning, and memory • Structures • Hippocampus: involved in learning and memories • Thalamus: brain’s relay station (sorts imp info); involved in sensory information (except smell) • Hypothalamus: • Regulates survival behavior such as eating, drinking, and sexual activity • Regulates autonomic nervous system  heart rate, blood pressure • Amygdala: involved in emotions (fear, anger, disgust), integrating senses, and memories

26. Nervous System—Central Nervous System (cont’d) • Brain (cont’d) • Hemispheres • Left and right hemispheres divided by corpus callosum (thick bundle of axons that acts as communication link btn hemispheres) • Diffs in function  roughly symmetrical in that same functions location in same place in each hemisphere • Analogy  one side does word processor, other does graphic design

27. Nervous System—Central Nervous System (cont’d) • Brain (cont’d) • Hemispheres (cont’d) • Language and Left Hemisphere • Paul Broca • French physician who treated several pts who had difficulty speaking but could comprehend written or spoken lang • Autopsies showed damage to area in lower left frontal lobe of brain • Broca’s area: plays crucial role in speech production • Karl Wernicke • German neurologist who discovered another area in left hemisphere that when damaged produced lang disturbance • Pts had difficulty understanding spoken or written communications. They could speak but often made no sense. • Autopsies revealed damage to same area in left temporal lobe • Aphasia: partial or complete inability to articulate or understand spoken or written lang b/c of brain injury/damage

28. Nervous System—Central Nervous System (cont’d) • Brain (cont’d) • Hemispheres (cont’d) • Split brain research • Roger Sperry • Operation used to stop recurring seizures in severe cases of epilepsy—involves cutting corpus callosum • Research  • Asked Ss to focus on point in middle of screen • Would flash word or picture to left or right of midpoint • Visual info to right of midpoint goes to left hemisphere and visual info to left goes to right hemisphere • Objects were also behind the screen hidden from view but reachable • Projected image of object (hammer) to left of midpoint (goes to right hemi) • S asked to say what object was  could not say hammer • When asked to use left hand to reach under partition to find object shown, could do this

29. Nervous System—Central Nervous System (cont’d)

30. Nervous System—Central Nervous System (cont’d) • Brain (cont’d) • Hemispheric specialization • Lateralization of function: idea that specific psychological functions are processed by one side of brain • Left hemisphere • Language abilities, speech, reading, and writing • Right hemisphere • Nonverbal emotional expression and visual-spatial tasks • Musical appreciation (not necessarily ability) • Keep in mind • Diffs are relative, not absolute • Both hemispheres involved

31. Nervous System—Central Nervous System (cont’d) • Brain (cont’d) • Handedness • Stats: 90% are right-handed; 10% are left-handed (we’re unique!) • Is handedness inherited? • Ultrasound show that more than 9 in 10 fetuses suck right thumb • If both parents right-handed, 1 in 10 chance child will be lefty (if one parent lefty and other righty, then 1 in 5 chance of having lefty) • Research  when infant lies down, which direction is head turned • Head-right usually had preference for right hand • Head-left usually had preference for left hand • Left-handed inds • Reading disabilities, allergies, and migraine headaches more common • More common among musicians, mathematicians, and artists • Brain research  left-handed inds still use left hemisphere for lang • Will show pattern of using both hands

32. Nervous System—Central Nervous System (cont’d) • Brain (cont’d) • Plasticity of the brain • Plasticity: brain’s ability to change (esp during childhood) function and structure to adapt to damage • Functional plasticity: brain’s ability to shift functions from damaged area to undamaged area • Structural plasticity: brain’s ability to change physical structure in response to learning, active practice, and environmental influence • Examples • If blind ind uses one finger to read Braille, brain area dedicated to that finger expands sense of touch • Loss of finger – sensory cortex will begin to receive info from adjacent fingers • http://www.youtube.com/watch?v=TSu9HGnlMV0