Topical Outline and Key Terms

I. The Central Nervous System

a. The central nervous system and peripheral nervous system (CNS and PNS) are the two subsystems of the nervous system.

1. Central nervous system (CNS): Includes the brain and the spinal cord.
2. Nerve: A bundle of axons (the long processes extending from neurons’ cell bodies) running together like a multiwire cable.
3. Tracts: The name for a bundle of axons inside the CNS.
4. Nucleus: A group of cell bodies in the CNS.
5. Ganglion: A group of cell bodies in the PNS.
6. The Forebrain
7. The Cerebral Hemispheres: Large, wrinkled structures which dominate the brain’s appearance.
8. Longitudinal fissure: A division running the length of the brain which separates the two cerebral hemispheres.
9. Gyrus: Each ridge in the surface of the brain.
10. Sulcus: The groove or space between two gyri.
11. Fissure: A large groove or space between two gyri.
12. Cortex: The outer surface of the brain, which is made up mostly of the cell bodies of neurons.
13. Cell bodies are not myelinated, resulting in a gray appearance rather than a whitish one; this is the source of the term “gray matter.”
14. The Four Lobes: Each hemisphere is named after the skull bone that covers it.
15. Dorsal: Directional term meaning towards the back.
16. Ventral: Directional term meaning towards the stomach.
17. Anterior: Directional term meaning towards the front.
18. Posterior: Directional term meaning towards the rear.
19. Superior: Directional term meaning above another structure.
20. Inferior: Directional term meaning below another structure.
21. Lateral: Directional term meaning towards the side.
22. Medial: Directional term meaning towards the middle.
23. Frontal lobe: Located anterior to the central sulcus and superior to the lateral fissure.
24. Central sulcus: A sulcus which separates the frontal lobe from the parietal lobe.
25. Lateral fissure: A prominent fissure which separates the frontal and parietal lobes from the temporal lobe.
26. Precentral gyrus: Extends the length of the central sulcus.
27. Motor cortex: Located in the precentral gyrus, this structure controls voluntary (nonreflexive) movement.
28. Broca’s area: A region which controls speech production, contributing grammatical structure and the motor control involved in speech.
29. Prefrontal cortex: A region involved in planning and organization of behavior, decision making, adjusting behavior in response to its consequences, and planning how to achieve goals.
30. Psychosurgery: The use of surgical intervention to treat cognitive and emotional disorders.
31. Parietal lobes: Located superior to the lateral fissure and between the central sulcus and the occipital lobe.
32. Primary somatosensory cortex: Located on the postcentral gyrus, processes the skin senses (touch, warmth, cold, and pain) and the senses that inform us about body position and movement.
33. Association areas: Areas which carry out further processing beyond what the primary area does, often combining information from other senses.
34. Neglect: A disorder in which the person ignores objects, people, and activity on the side opposite the damage.
35. Temporal lobes: Regions containing the auditory projection area, visual and auditory association areas, an additional language area, and structures important in learning and memory.
36. Auditory cortex: Region which receives sound information from the ears and lies on the superior gyrus of the temporal lobe, mostly hidden from view within the lateral fissure.
37. Wernicke’s area: Association area that interprets language input arriving from the nearby auditory and visual areas; it also generates spoken language through Broca’s area and written language by way of the motor cortex.
38. Inferior temporal cortex: Located in the lower part of the lobe, as the name implies, and plays a major role in the visual identification of objects.
39. Occipital lobes: The location of the visual cortex.
40. Visual cortex: The region where visual information is processed
41. The Thalamus and Hypothalamus
42. Thalamus: A region that lies just below the lateral ventricles, where it receives information from all the sensory systems except olfaction (smell) and relays it to the respective cortical projection areas.
43. Hypothalamus: A smaller structure just inferior to the thalamus which plays a major role in controlling emotion and motivated behaviors, such as eating, drinking, and sexual activity.
44. Pineal gland: A gland which secretes melatonin, a hormone that induces sleep; it controls seasonal cycles in nonhuman animals and participates with other structures in controlling daily rhythms in humans.
45. The Corpus Callosum: A dense band of fibers that carry information between the hemispheres.
46. The Ventricles
47. Ventricles: Cavities in the brain which develop from the hollow interior of the nervous system.
48. Cerebrospinal fluid: Carries material from the blood vessels to the CNS and transports waste materials in the other direction.
49. The Midbrain and Hindbrain
50. Midbrain: Contains structures that have secondary roles in vision, hearing, and movement.

a. Superior colliculi: Structures that help guide eye movements and fixation of gaze.

b. Inferior colliculi: Structures that help locate the direction of sounds.

1. Hindbrain
2. Pons: Region which contains centers related to sleep and arousal, which are part of the reticular formation.
3. Reticular formation: Collection of many nuclei running through the middle of the hindbrain and the midbrain.
4. Medulla: Forms the lower part of the hindbrain; its nuclei are involved with control of essential life processes, such as cardiovascular activity and respiration (breathing).
5. Cerebellum: Refines movements initiated by the motor cortex by controlling their speed, intensity, and direction.
6. The Spinal Cord: A finger-sized cable of neurons that carries commands from the brain to the muscles and organs and sensory information into the brain.
7. Dorsal root: A region of each spinal nerve where sensory neurons enter the spinal cord.
8. Ventral root: The region in which axons of motor neurons pass out of the spinal cord.
9. Reflex: A simple, automatic movement in response to a sensory stimulus.
10. Protecting the Central Nervous System
11. Meninges: A protective three-layered membrane.
12. Blood-brain barrier: Limits passage between the bloodstream and the brain, provides constant protection from toxic substances and from neurotransmitters circulating in the blood.
13. The peripheral nervous system (PNS)
14. Peripheral nervous system (PNS): Made up of cranial nerves and spinal nerves, and can be divided into the somatic nervous system and autonomic nervous system.
15. Cranial nerves: Nerves which enter and leave the underside of the brain.
16. Spinal nerves: Nerves which connect to the sides of the spinal cord at each vertebra.
17. Somatic nervous system: Includes the motor neurons that operate the skeletal muscles—that is, the ones that move the body—and the sensory neurons that bring information into the CNS from the body and the outside world.
18. Autonomic nervous system (ANS): Controls smooth muscle (stomach, blood vessels, etc.), the glands, and the heart and other organs.
19. The Cranial Nerves: Enter and exit from the ventral side of the brain.
20. The Autonomic Nervous System
21. Sympathetic nervous system: Activates the body in ways that help it cope with demands such as emotional stress and physical emergencies.
22. Parasympathetic nervous system: Slows the activity of most organs to conserve energy but also activates digestion to renew energy.
23. Sympathetic branch arises from thoracic and lumbar areas of the spinal cord.
24. Development and Change in the Nervous System

a. The stages of development

i. Proliferation occurs early in life, and is the birth and division of new neurons.

ii. In migration, the neurons travel along radial glia to their ultimate destinations.

iii. During circuit formation, developing neurons send processes to target cells and form functional connections.

1. Axons use growth cones to find their way to their destinations.

iv. Neurons that are unsuccessful in finding a place on a target cell die in a process called circuit pruning.

1. Neurotrophins enhance the survival of neurons.

2. Plasticity is the ability of neural systems to be modified.

3. Mistakes during development can have serious consequences .

a. Fetal alcohol syndrome results from alcohol exposure during migration.

b. Radiation disrupts proliferation and migration.

v. Myelination begins during development and continues through adolescence.

b. How experience modifies the nervous system

i. Reorganization involves a shift in connections that alters the function of an area of the brain.

ii. Reorganization may be beneficial, for example, in the increase in finger areas in the somatosensory cortex in syndactyly patients with surgical separation of their fingers, or detrimental as in phantom pain.

c. Damage and recovery in the Central Nervous System

i. Stroke and TBI (traumatic brain injury) provide opportunities to explore damage and recovery in the brain.

ii. Limitations on recovery

1. Regeneration, the regrowth of severed axons, does not occur in the mammalian CNS.

2. Neurogenesis the birth of new neurons, occurs only in the hippocampus and near the lateral ventricles.

iii. Compensation and reorganization

1. Compensation occurs when uninjured tissue takes over the functions of neurons lost to injury.

2. Reorganization is more dramatic, can involve an entire hemisphere, and is often seen in recovery from language impairment.

3. Hydrocephalus occurs when CSF is blocked, typically resulting in retardation.

iv. Possibilities for CNS repair are being explored by researchers

1. Attempts to induce growth in damaged spinal neurons

2. Actor Christopher Reeve contributed greatly to the exploration of CNS repair mechanisms through his own recovery efforts and the creation of a private foundation before his death.

3. Stem cells are undifferentiated cells and thus have the potential to replace damaged neural tissue.