Chapter 2: Brain and Behavior

1. Chapter 2: Brain and Behavior

2. Neuron and Its Parts • Neuron: Individual nerve cell; 100 billion in brain • Dendrites: Receive messages from other neurons • Soma: Cell body; body of the neuron • Axon: Carries information away from the cell body • Axon Terminals: Branches that link the dendrites and soma of other neurons

3. Figure 2.1

4. Main Parts of the Neuron

5. Figure 2.2

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

7. More on Nerves • Ion Channels: Tiny holes through the axon membrane • Negative After-Potential: When a neuron is less willing to fire • Synapse: Microscopic space between two neurons over which messages pass

8. Figure 2.3

9. Figure 2.4

10. Neuron and Neural Impulse Mac OS 8-9 Mac OS X Windows

11. Neurotransmitters • Chemicals that alter activity in neurons; brain chemicals • Acetylcholine: Activates muscles • Dopamine: Muscle control • Serotonin: Mood and appetite control • Receptor Site: Areas on the surface of neurons and other cells that are sensitive to neurotransmitters or hormones

12. Normal Synaptic Transmission of Dopamine

13. Synaptic Transmission Mac OS 8-9 Mac OS X Windows

14. Figure 2.6

15. Neural Regulators • Neuropeptides: Brain chemicals that regulate activity of other neurons • Enkephalins: Relieve pain and stress; similar to endorphins • Endorphins: Released by pituitary gland; also help to relieve pain • Placebos raise endorphin levels

16. Interaction of Endorphins & Opiates

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

18. Nerves and Neurons (cont.) • Neurilemma: Thin layer of cells wrapped around axons outside brain and spinal cord; forms a tunnel that damaged fibers can follow as they repair themselves • Neurogenesis: Production of new brain cells; brain loses thousands of cells each day and grows new neurons at same time to replace them

19. Neural Networks • Central Nervous System (CNS): Brain and spinal cord • Peripheral Nervous System: All parts of the nervous system outside of the brain and spinal cord

20. Two Divisions of the Peripheral Nervous System • Somatic System: Links spinal cord with body and sense organs; controls voluntary behavior • Autonomic System: Serves internal organs and glands; controls automatic functions such as heart rate and blood pressure

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

22. Figure 2.7

23. Figure 2.8

24. Figure 2.9

25. 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 without passing through the spinal cord; also work to communicate messages

26. The Spinal Cord and Behavior • Reflex Arc: Simplest behavior in which a stimulus provokes an automatic response • Sensory Neuron: Nerve cell that carries messages from the senses toward the CNS • Motor Neuron: Cell that carries commands from the CNS to the muscles and glands • Effector Cells: Cells capable of producing a response

27. Researching the Brain • Ablation: Surgical removal of tissue • Deep Lesioning: A thin wire electrode is lowered into a specific area inside the brain; Electrical current is then used to destroy a small amount of brain tissue • Electrical Stimulation of the Brain (ESB): When an electrode is used to activate target areas in the brain • Electroencephalograph (EEG): A device that detects, amplifies, and records electrical activity in the brain

28. Figure 2.10

29. Brain Imaging Techniques • Computed Tomographic Scanning (CT): Computer-enhanced X-ray of the brain or body • Magnetic Resonance Imaging (MRI): Uses a strong magnetic field, not an X-ray, to produce an image of the brain and body

30. More Brain Imaging Techniques • Functional MRI (fMRI): MRI that makes brain activity visible • Positron Emission Tomography (PET): Computer-generated color image of brain activity, based on glucose consumption in the brain

31. Figure 2.11

32. Figure 2.16

33. 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 • Spatial Neglect: Right hemisphere stroke victims pay no attention to the left side of visual space

34. Split Brains • Corpus Callosum: Bundle of fibers connecting cerebral hemispheres • In Split Brains, Corpus Callosum is cut; done to control severe epilepsy (seizure disorder) • Result: The person now has two brains in one body • This operation is rare and is often used as a last resort

35. Figure 2.21

36. The Corpus Callosum

37. Figure 2.18

38. Right Brain/Left Brain • Humans use 95 percent of our left brain for language

39. The Left Hemisphere • Left hemisphere is better at math, judging time and rhythm, and coordinating order of complex movements • Processes information sequentially

40. The Right Hemisphere • Right hemisphere is good at perceptual skills, and at expressing and detecting other’s emotions • Processes information simultaneously

41. Figure 2.20

42. Figure 2.30

43. Central Cortex Lobes • Areas bordered by major grooves or fissures or defined by their functions • Occipital Lobe: Back of brain; vision center • Parietal Lobe: Just above occipital; bodily sensations such as touch, pain, and temperature (somatosensory area)

44. The Occipital Lobe

45. The Parietal Lobe

46. The Last Two Lobes • 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

47. Figure 2.23

48. The Temporal Lobe

49. The Frontal Lobe

50. Figure 2.24