The Brain & Nervous System

1. The Brain & Nervous System

2. History • Known to relate to thought and behavior for over 3500 years • Edwin Smith Surgical Papyrus • Greeks thought the brain • Was the seat of the mind • Was responsible for intelligence • Cooled the blood

3. Trepanning • Practiced since at least 6500 BCE • Still used in limited cases • Subdural Hematomae • Most recent psychological use from 2000 • Used for • Mental Illness • Increased “brainpower”

4. History • Descartes believed in dualism • Mind was in but not of the Brain • Interacted at the Pineal Gland • Vesalius • Found nerves transmitted sensation and motion • Nerves were not hollow

5. History • Galvani first discovered that the nervous system used electricity • Touched a frog leg with a charged scalpel, which caused a leg twitch

6. Structure • The nervous system breaks down into two basic parts • Central Nervous System (Brain & Spinal Cord) • Peripheral Nervous System (Everything Else) • PNS further divides into • Somatic (voluntary) and Autonomic (involuntary) • Autonomic subdivides into sympathetic and parasympathetic

8. Peripheral Nervous System • Somatic System is everything that is voluntary • Arms, Legs, Eyes, etc. • The one exception is a reflex arc • Bypasses the brain • Reaction at spinal cord • Action is quicker than nerve impulse to brain

9. Peripheral Nervous System • Autonomic subsystem controls automatic/smooth muscles • Heart, Lungs, etc • Sympathetic promotes “fight or flight” responses • Dilates pupils, increases heart rate, inhibits peristalsis • Parasympathetic promotes “rest & digest” • Constrict pupils, slow heart rate, constricts bronchi • Sympathetic & parasympathetic are opponent systems

10. Neurons • The brain and all nerves are made up of neurons • The largest is over 3 feet long • Every neuron is made up of a • Dendrite • Cell Body • Axon • Axon Terminals

12. Neurons • Neurons fire electrically • Have an action potential • Start off polarized • Excess of Na+ & Cl- outside, K+ inside • Resting potential is around -70 mV • Depolarization occurs when channels open • Ions flow in and out • Firing occurs around -45 mV • Neural firings occur at a threshold • All or none • Intensity = rate of fire

13. Neurons • After firing, neurons enter a refractory period • Absolute refractory period • Impossible to evoke another firing • Na+ channels are inactive • Relative refractory period • Requires stronger than normal stimulus

14. Neurons

15. Neurons • Some neurons are myelinated • White matter (vs. Gray matter) • Insulation • Hops from one uninsulated part to another • Nodes of Ranvier • Demyelinating diseases • MS, transverse myelitis, Guillan-Barre, etc • Vision problems, weakness, odd sensations, loss of coordination

17. Neurons • Neurons don’t touch • Synapse is a gap through which communication occurs • Axons release a transmitter • Dendrites pick it up

18. Neurotransmitters • Neurons communicate with neurotransmitters • Acetylcholine (muscle movement, arousal, reward) • Dopamine (motivation, punishment/reward) • Epinephrine/Norepinephrine (adrenaline, allergy) • Serotonin (mood) • Endorphins (opiods) • GABA (mood, anxiety) • More than 40 others (and homologues) • Lock-and-Key model • Video

19. Drugs • Some drugs work by exciting/antagonize production • Nicotine (acetylcholine) • SSRI (seretonin) • Some drugs are better keys than neurotransmitters • Heroin (Endorphins) • Cocaine (Dopamine) • Alcohol (GABA)

20. The Brain • Divided into two hemispheres • Connected by Corpus Callosum • Various lobes & structures • Mirrored in each hemisphere • E.g. “left & right _____” • Watch

21. Brain Structures • Brainstem • Thalamus • Cerebellum • Limbic System • Cerebral Cortex

22. Brainstem • Basic life functions • Medulla (pith/marrow) • Heart • Lungs • Reticular (net) Formation • Arousal/Alertness • Consciousness • Pain • Pons (bridge) • Gathering of cranial nerves

23. Thalamus • “Inner Chamber” • Acts as a sensory relay station • Not as well understood • Implicated in Korsakoff’s syndrome and Hereditary Familial Insomnia

24. Cerebellum • “Little Brain” • Motor Control • Damage does not cause paralysis • Active in motor learning • Unconscious/Automatic actions • Signals move unidirectionally • Unlike all other parts of brain

25. Limbic System • Amygdala (Almond) • Emotionally significant stimuli (reward/fear) • Stimulation -> Agression; Destruction -> Placid • Hypothalamus (Under Thalamus) • Body maintenance • Hunger, thirst, sex, temperature • Adjacent to pituitary • Three F’s (Fighting/Fleeing, Feeding, Sex)

26. Hypothalamus Damage

27. Limbic System • Amygdala (Almond) • Emotionally significant stimuli (reward/fear) • Stimulation -> Agression; Destruction -> Placid • Hypothalamus (Under Thalamus) • Body maintenance • Hunger, thirst, sex, temperature • Adjacent to pituitary • Hippocampus (Seahorse) • Necessary for long-term memory formation • Think “Memento”

28. Cerebral Cortex • Frontal Lobes • Sensorimotor Cortex • Parietal Lobes • Temporal Lobes • Occipital Lobes

29. Occipital Lobe • Back of the brain • Above Cerebellum • Controls visual processing • Highly specialized Cell groups • Line Angles • Incredibly basic • “Seeing stars”

30. Temporal Lobes • Specific visual processing • Faces • Hearing • Auditory nerve connects • Episodic/Declarative memory • “And then, this happened” • Left side involved in speech/language • Broca’s area = speech production • Wernicke’s area = speech comprehension

31. The Man Who Mistook His Wife for a Hat • Temporal Lobe damage -> prosopagnosia • Face blindness • Cannot connect faces to semantic information about people • May not recognize a person until they speak • Oliver Sacks

32. Parietal Lobes • Integrates sensory information • Numeracy • What is the relationship between 8 and 2? • Where and how of vision • Spatial relations • Action saliency • Hemispatial neglect • Right lobe usually

33. Sensorimotor Cortex • Between parietal & frontal lobes • Governs movement and sensation • Areas relate to sensitivity and fine motor control • Not size • Phantom limb syndrome

34. Frontal Lobes • Involved in planning • Consequences • Moral judgment • Response inhibition • Similarity judgments • Doesn’t mature until early/mid twenties • Underactive in ADHD patients

35. Integrating It All • Occipital lobe processes shapes • Temporal lobe tells me it’s a dog • Registers barking • Parietal lobe tells me it’s angry and running towards me • Limbic system tells me to run • Engages my sympathetic nervous system • Motor cortex works my legs

36. Lateralization • Brain divides into left & right hemispheres • Lateralization = specialization of hemispheres • Left is logical, right is intuitive • Grammar & literal meaning on left, prosody and intonation on the right • The brain is wired contra-laterally • Left controls right & vice-versa • Left-handed people are less lateralized • Cause & effect unclear

37. Lateralization Test • Mark which of the following you would prefer (not necessarily ability) • A) Major in Logic • B) Write a Letter • C) Fix things at home • D) Major in Art

38. Mark which of the following you would prefer (not necessarily ability) • A) Be a movie critic • B) Learn new Words • C) Improve your skills in a game • D) Create a new toy

39. Mark which of the following you would prefer (not necessarily ability) • A) Improve your strategy in a game • B) Remember people’s names • C) Engage in sports • D) Play an instrument by ear

40. Mark which of the following you would prefer (not necessarily ability) • A) Review a book • B) Write for a magazine • C) Build new shelves at home • D) Draw a landscape or seascape

41. Mark which of the following you would prefer (not necessarily ability) • A) Analyze market trends • B) Write a movie script • C) Do carpentry work • D) Imagine a new play

42. Mark which of the following you would prefer (not necessarily ability) • A) Analyze management practices • B) Locate words in a dictionary • C) Put jigsaw puzzles together • D) Paint in oil

43. Mark which of the following you would prefer (not necessarily ability) • A) Be in charge of computer programming • B) Study word origins and meanings • C) Putter in the yard • D) Invent a new gadget

44. Mark which of the following you would prefer (not necessarily ability) • A) Analyze production costs • B) Desscribe a new product in words • C) Sell a new product on the market • D) Draw a picture of a new product

45. Mark which of the following you would prefer (not necessarily ability) • A) Explain the logic of a theory • B) Be a copy writer for ads • C) Work with wood and clay • D) Invent a story

46. Mark which of the following you would prefer (not necessarily ability) • A) Be a comparison shopper • B) Read about famous men and women • C) Run a traffic control tower • D) Mold with clay and putty

47. Mark which of the following you would prefer (not necessarily ability) • A) Analyze your budget • B) Study literature • C) Visualize and re-arrange furniture • D) Be an artist

48. Mark which of the following you would prefer (not necessarily ability) • A) Plan a trip • B) Write a novel • C) Build a house/shack • D) Make crafts your hobby

49. Lateralization Test • Add up your “a” and “b” responses • This is your left brain score • Add up your “c” and “d” responses • This is your right brain score • A difference of more than 3 indicates strong lateralization • Less than 3 is balanced • My score is 11 left/1 right

50. Corpus Callosum • The hemispheres communicate via corpus callosum • Mostly, not exclusively • Bundle of nerves that serve as a connector • Highly specialized