Brain & Behavior

1. Brain & Behavior

2. Goals for Lecture & Readings • Understand the mechanisms of neural communication • Understand the form and function of the nervous system

3. Phineas Gage • 1848 • Railway worker • Tamping iron blew through his head • Memory and movement intact, could learn new things • But, personality changed

4. Phineas Gage • 1980s • Computer modelling shows path of rod • Damaged ventromedial frontal lobe • Brain region linked to personality

5. “Biopsychology” • Biological approach to the study of psychology • Various approaches to understand links between nervous system and behavior

6. Characteristics of Biopsychology • Humans & nonhumans subjects • Experiments and case studies • Basic and applied research

7. Divisions of Biopsychology • Physiological Psychology • Manipulate nervous system (surgery, chemicals); theories of neural control of behavior • Psychopharmacology • Effects of drugs on neural activity and behavior • Neuropsychology • Study behavioral deficits produced by brain damage; often applied

8. Divisions of Biopsychology • Psychophysiology • Record physiological responses to understand relation between physiology and psychology • Comparative Psychology • Behavior of different species; focus on genetics, evolution, function

9. Building Blocks of Nervous System • Neurons • Specialized nerve cells • Send/receive nerve impulses • Sensory, motor, interneurons • Neurons have a right-hand man, called glial cells • hold neurons in place and provide nutrients • Outnumber neurons 10:1

10. Neurons • Three basic parts: • Cell body (soma) • Metabolic centre, genetic material, etc… • Dendrites • Specialized fibres for receiving info • Axon • Conducts messages away from cell body

11. Also, Node of Ranvier Terminal buttons

12. Neurons • Neuron fires when stimulated • Heat • Light • Pressure • Other neurons • The impulse is called an action potential

13. Electrical Activity of a Resting Neuron • Membrane Potential: • Difference in electrical charge between inside and outside of cell • Resting Potential: • -70 mV • Lots of Na(+) ions outside cell • Lots of protein(-) molecules inside cell

14. When a Neuron is Stimulated… • Stimulation causes distribution of particles to change • Na(+) flows in • Attracted to protein(-) • Inside now (+) relative to outside

15. Neural Conduction • Action Potential: • Massive, brief reversal of membrane potential from –70 to +50 mV • After an action potential, neuron has to recharge, so to speak • K(+) pumped out of cell, (-) charge restored • Refractory period – neuron cannot fire again during this process

16. Myelinated Axons • Myelin is fatty tissue • Faster conduction • Action potential “jump” from one Node of Ranvier to the next • Multiple Sclerosis – myelin sheath destroyed

17. From One Neuron to the Next • Synapse: • The site of adjacent neurons • “Synapse” - Greek word for “gap” • (Every mall in Athens has a store called “The Synapse”) • Action potentials at terminal buttons cause release of chemical neurotransmitters • Neurotransmitters bind to sites on adjacent neurons and thereby induce electrochemical changes in them

19. Neurotransmitters • When they bind to an adjacent neuron, they cause chemical reactions • Excitatory neurotransmitters • Cause Na(+) to enter cell • Makes action potential more likely • Makes it more likely the cell will send signals to other neurons

20. Neurotransmitters • Inhibitory neurotransmitters • May cause K(+) to leave the cell, or Chloride(-) to enter • This makes an action potential less likely • makes it less likely the cell will send signals to other neurons

21. Some Neurotransmitters • Acetylcholine • Excitatory at synapses involved in memory and movements • Dopamine • Excitatory; movement, emotional arousal

22. Effects of Drugs • Drugs affect behavior and thought by influencing the activity of neurons • Agonists • Mimic a particular neurotransmitter • Increase activity of neurotransmitter • Antagonists • Inhibits activity of a neurotransmitter

23. Effects of Drugs • Nicotine is an agonist for Dopamine • Reward and pleasure • Amphetamines and Cocaine: agonists for Dopamine and Norepinephrine • Reward, pleasure, arousal

25. Major Divisions of Nervous System • Central Nervous System (CNS): • Brain • Spinal cord • Peripheral Nervous System (PNS): • Somatic Nervous System • Autonomic Nervous System

26. Peripheral Nervous System • Somatic Nervous System: • Interacts with external environment • Sensory info from receptors (in skin, joints, eyes, ears, etc.) to CNS • Signals sent back from CNS to skeletal muscles • Deals largely with voluntary actions

27. Peripheral Nervous System • Autonomic Nervous System: • Involved in regulation of internal environment • Deals largely with involuntary functions • Signals from organs to CNS • Signals from CNS to organs • Sympathetic nerves • Prepare for action • Parasympathetic nerves • Conserve energy

28. Central Nervous System • Spinal Cord • Highway for most nerves • H-shaped core of gray matter • Cell bodies, unmyelinated interneurons • Surrounding white matter • Ascending & descending myelinated axons

29. The Brain

30. The Brain

31. One More Brain Diagram

32. EEG Measures electrical activity

33. CAT Scan Computerized Axial Tomography

34. PET Scan Positron Emission Tomography

35. MRI Magnetic Resonance Imaging

36. The Brain, Function & Form • Brainstem • Medulla: • Tracts that carry signals between brain and rest of body • Reticular formation: • Involved in sleep, attention, movement, and various autonomic functions

37. The Brain, Function & Form • Cerebellum • “Little brain” • Walking • Balance • Timing and coordination of movements

38. The Brain, Function & Form • Thalamus • Sensory relay station • Info from sensory receptors processed and sent to sensory cortex • Basal Ganglia • Surrounds thalamus • Deliberate movements • Parkinson’s disease

39. The Brain, Function & Form • Limbic System • Hippocampus • memory • Amygdala • emotion • Hypothalamus • Motivation; biological drives

40. The Brain • Cerebral Cortex: • Outermost layer of brain • Wrinkled • Many connections to other areas • Frontal cortex complex cognition • Temporal  auditory, language • Occipital  visual • Parietal  sensory stuff