Chapter 2 Neuroscience

1. Chapter 2Neuroscience

2. A Little Exercise See in class!

3. Brain and Mind

4. Topics to Explore • The Neuron • The Peripheral Nervous System • The Central Nervous System

5. Part 1The Neuron

6. Neuron and Its Parts Neuron: Individual nerve cell; 100 billion in brain • Dendrites: Receive messages from other neurons; have thousands of branches • Soma: Cell body; metabolic center of neuron; contains genetic material • Axon: Carries information away from the cell body; longest part of neuron • Axon Terminals: Branches that link the dendrites and soma of other neurons • Synaptic Gap: Space between the end of the axon of one neuron and the dendrites of an adjacent neuron

7. Picture of a Neuron

8. The Nerve Impulse • Resting Potential: Electrical charge of an inactive neuron • Threshold: Trigger point for a neuron’s firing • Action Potential: Nerve impulse

9. Resting Potential • Resting Potential: Tiny charge between inside & outside of neuron • Created by electrically charged particles (ions) • Some concentrated outside the cell (sodium and chloride ions) • Some concentrated inside the cell (Potassium ions) • How is the charge maintained? • Sodium-potassium pump • Selectively permeable cell membrane

10. Action Potential • Action potential: Change in potential, primarily because of messages from other neurons • Excitatory messages: Cell loses the negative charge; Depolarization • Inhibitory messages: Cell becomes more negatively charged; Hyperpolarization

11. Resting vs. Action Potential

12. Graphic: Action Potential

13. Graphic: Action Potential

14. Graphic: Synaptic Gap

15. Neurotransmitters Neurotransmitters: Chemicals that alter activity in neurons; brain chemicals. Messages from one neuron to another pass over the synapse, the microscopic gap between neurons Receptor Site: Areas on the surface of neurons and other cells that are sensitive to neurotransmitters Antagonist: drug that decreases activity of a neurotrans-mitter

16. Some Neurotransmitters • Acetylcholine: involved in learning, memory, and muscle contractions. Botulism toxin prevents release of acetylcholine, resulting in paralysis • Dopamine: involved in arousal, mood, and movement. In Parkinson’s, receptors in brain fail to react to dopamine, leading to tremors, rigidity and problems initiating movement • Serotonin and Norepinephrine: involved in arousal and mood. Cocaine blocks re-uptake of both neurotransmitters, resulting in “high” • GABA (gamma-aminobutyric acid): main inhibitory neurotrans-mitter; lowers arousal and anxiety • Endorphins: lower pain perception. Morphine and heroin bind to endorphin receptors, increasing endorphin activity.

17. Nerves and Neurons • Nerves: Large bundles of neurons • Myelin: Fatty layer of tissue that coats axons • Multiple Sclerosis (MS) occurs when myelin layer is destroyed; numbness, weakness, and paralysis occur

18. A Little Exercise Demonstration of the speed of a neural impulse.

19. An Organizational Pause:Organization of the Nervous System

20. Major Sections of the Nervous System • Central Nervous System (CNS): Brain and spinal cord • Peripheral Nervous System: All parts of the nervous system outside of the brain and spinal cord • - Autonomic System: Serves internal organs and glands; controls automatic functions such as heart rate and blood pressure • - Somatic System: Links spinal cord with skeletal muscles and sense organs; controls voluntary behavior

21. Organization of Nervous System

22. Graphic: Nervous System

23. Part 2The Peripheral Nervous System • The Autonomic Nervous System • The Somatic Nervous System

24. Divisions of Autonomic System • Sympathetic: Arouses body; emergency system • Parasympathetic: Quiets body; most active after an emotional event

25. Functions of Autonomic Nervous System

26. Three Components of Emotion • Physical component: state of physiological arousal triggered by autonomic nervous system • Behavioral component: outward expression of the emotion, including facial expression & behavior • Cognitive component: appraisal of the situation to determine which emotion we are experiencing and why

27. James-Lange Theory of Emotion

28. Cannon-Bard Theory of Emotion

29. Schachter-Singer Theory

30. Comparison of Three Theories of Emotion

31. Somatic Nervous System • Motor Nervous System: transfers messages from CNS to control function of voluntary muscles • Sensory Nervous System: transfers messages from sensory organs to CNS; brings information from outside the body to the brain to be processed

32. Structures in Somatic System • Sensory neuron: neuron that transmits information from sensory organ to CNS • Motor neuron: neuron that transmits information from CNS to voluntary muscle • Connector neuron: neuron in spinal cord connecting sensory and motor neurons to form reflex arc. • Reflex: An innate, automatic motor response to a specific sensory stimulus

33. Graphic: Somatic Nervous System

34. Motor & Somatosensory Areas in Cerebral Cortex

35. “homunculus” = “a diminutive human being” Motor Homunculus

36. Somesthetic Homunculus

37. A Little Exercise A demonstration of the somatosensory system, using toothpicks and little rulers.

38. Part 3The Central Nervous System • The Spinal Cord • The Brain • - The Central Core • - The Limbic System • - The Cerebral Cortex

39. The Spinal Cord • Spinal Nerves: 31 of them; carry sensory and motor messages to and from the spinal cord • Cranial Nerves: 12 pairs that leave the brain directly; also work to communicate messages • Spinal cord functions to connect peripheral nervous system to the brain

40. The Central Core(aka the “old brain”) • Medulla: Connects brain with the spinal cord and controls vital life functions such as heart rate and breathing • Cerebellum: Regulates posture, muscle tone, muscular coordination, and procedural learning • Reticular formation: Associated with levels of arousal and consciousness, as well as some reflexes (breathing, coughing, sneezing, vomiting) • Thalamus: serves as a relay station for incoming sensory Information • Basal ganglia: involved in physical movement

41. Graphic: Central Core

42. The Limbic System • At the top border (limbus in Latin) of the brain stem. • Hypothalamus: controls pituitary gland (directing activity of endocrine system) and autonomic nervous system; involved in basic drives (eating, drinking, sex) • Hippocampus: involved in formation of memories • Amygdala: involved in regulating emotional experiences, particularly initial emotional responses

43. Graphic: Limbic System

44. Neocortex • Cerebral Cortex: Outer layer of the cerebrum • Cerebrum: Two large hemispheres that cover upper part of the brain • Corticalization: Increase in size and wrinkling of the cortex • Cerebral Hemispheres: Right and left halves of the cerebrum • Corpus Callosum: Bundle of fibers connecting cerebral hemispheres

45. Graphic: Relative Size

46. Graphic: Corpus Callosum

47. Left & Right Hemispheres

48. Left Brain/Right Brain • About 95 percent of our left brain is used for language • Left hemisphere better at math, judging time and rhythm, and coordinating order of complex movements • Processes information sequentially • Right hemisphere good at perceptual skills, and at expressing and detecting other’s emotions • Processes information simultaneously

49. Graphic: Left vs. Right

50. Lobes of the Neocortex • Occipital Lobe: Back of brain; vision center • Parietal Lobe: Just above occipital; bodily sensations such as touch, pain, and temperature (somatosensory area) • Temporal Lobe: Each side of the brain; auditory and language centers • Frontal Lobe: Movement, sense of smell, higher mental functions; contains motor cortex; controls motor movement