3.3-3.5

• Central Nervous System (CNS)


  Comprised of the brain and spinal cord
• Peripheral Nervous System (PNS)


  Connects the CNS to the rest of the body
• Parts of the Peripheral Nervous System

  • Somatic Nervous System
  • Autonomic Nervous System
• Somatic Nervous System


  Associated with activities traditionally thought of as conscious or voluntary
• Somatic Nervous System


  • Involves the relay of sensory and motor information to and from the CNS
  • Consists of motor neurons and sensory neurons
• Motor neurons


  Carry instructions from the CNS to the muscles (efferent fibers)
• Sensory neurons


  Carry sensory information to the CNS (afferent fibers)
• Autonomic Nervous System


  Controls internal organs and glands, generally outside the realm of voluntary control
• Divisions of the Autonomic Nervous System

  • Sympathetic Nervous System
  • Parasympathetic Nervous System
• Sympathetic Nervous System


  Involved in preparing the body for stress-related activities
• Parasympathetic Nervous System


  Associated with returning the body to routine, day-to-day operations
• Homeostasis


  A state of equilibrium or balance, in which biological conditions are maintained at optimal levels
• Fight or flight response


  A constellation of physiological changes that allow the body access to energy reserves and heightened sensory capacity to face a threat or run away to safety
• Sympathetic nervous system is activated

  Body undergoes changes to prepare for stress-related activities
• Threat is resolved


  Parasympathetic nervous system takes over and returns bodily functions to a relaxed state
• Spinal cord


  Connects the brain to the outside world, acts as a relay station, has its own system of automatic processes (reflexes)
• Spinal cord


  • Merges with the brain stem at the top, ends just below the ribs
  • Functionally organized in 30 segments corresponding to vertebrae
  • Sensory nerves bring messages in, motor nerves send messages out
  • Allows for immediate reflexes without input from the brain
• Spinal cord injuries cause paralysis in all lower segments cut off from the brain
• Neuroplasticity


  The nervous system's ability to change and adapt, including creating new synapses, pruning unused synapses, changes in glial cells, and birth of new neurons
• Neuroplasticity allows for remarkable recovery of function even later in life, as seen in the case of Bob Woodruff
• Cerebral cortex


  The surface of the brain, characterized by gyri (folds/bumps) and sulci (grooves)
• Hemispheres


  The left and right halves of the brain, separated by the longitudinal fissure
• Hemispheres


  • Show some lateralization of function, with the left hemisphere controlling the right half of the body and vice versa
  • Connected by the corpus callosum, which allows communication between the hemispheres
• Split-brain patients show interesting behaviors like being unable to name pictures shown in their left visual field
• Much of what we know about brain function comes from studying behavioral changes caused by brain damage like strokes
• When the more verbal left hemisphere sees the picture that the left hand drew, the patient is able to name it (assuming the left hemisphere can interpret what was drawn by the left hand)
• Corpus callosum


  • Connects the left and right hemispheres of the brain
• Damage to the brain


  • Studying changes in the behavior and ability of individuals who have suffered damage to the brain
  • Studying the behavioral changes caused by strokes to learn about the functions of specific brain areas
• Stroke causes a loss of brain function in the affected region
• The types of deficits displayed after a stroke will be largely dependent on where in the brain the damage occurred
• Theona


  An intelligent, self-sufficient woman, 62 years old, who suffered a stroke in the front portion of her right hemisphere
• Theona suffered a stroke in the front portion of her right hemisphere


  She has great difficulty moving her left leg
• Theona suffered a stroke

  She sometimes eats grapes, strawberries, and apples directly from their bins before paying for them
• Prefrontal cortex


  Associated with judgment, reasoning, and impulse control
• Forebrain


  The largest part of the brain, containing the cerebral cortex and subcortical structures
• Cerebral cortex


  • Associated with higher level processes such as consciousness, thought, emotion, reasoning, language, and memory
• Lobes of the brain

  • Frontal
  • Parietal
  • Temporal
  • Occipital
• Frontal lobe


  Involved in reasoning, motor control, emotion, and language
• Motor cortex


  • Involved in planning and coordinating movement
• Prefrontal cortex


  • Responsible for higher-level cognitive functioning