Forebrain

Diencephalon - structures surrounding 3^rd ventricle

1. Pineal gland - endocrine gland that secretes melatonin, regulation of diurnal cycles
2. Thalamus - large ovoid masses lateral to 3^rd ventricle, contains large number of nuclei
   1. All sensory information from the body terminates in thalamus except olfactory
   2. Filters sensory information to cerebral cortex, plays essential role in awareness & gaining knowledge
   3. Relays sensory information about emotional state, pain, taste, touch, pressure, temperature, proprioception, visual and auditory to cerebral cortex
   4. Sorts information according the nature of the stimulus and body location involved for projection to association areas in cerebral cortex
3. Hypothalamus - floor of 3^rd ventricle, contains many nuclei
   1. Mamillary bodies - reflexes related to sense of smell and eating
   2. Controls subconscious somatic motor activities associated with rage, pain, pleasure, and sexual arousal, ex. changes in facial expression
   3. Controls autonomic centers in pons and medulla oblongata regulating heart rate, blood pressure, respiration and digestion
   4. Coordination between voluntary and autonomic functions, e.g. imagining dangerous situation causes heart and respiration rates to increase
   5. Preoptic areas coordinate other CNS centers and regulate physiological systems (vasomotor) to maintain normal body temp
   6. Ventrolateral preoptic area (VLPO) - blocks the RAS and causes sleep
   7. Produces emotional and behavioral drives that lead to conscious or subconscious behavioral changes, ex. feeding center produces hunger, thirst center (ADH)
   8. Suprachiasmatic nucleus coordinates day-night cycle
      1. Receives input from eyes and adjusts output of hypothalamic nuclei, pineal gland & RAS
   9. Endocrine functions
      1. Secretes two hormones - ADH and oxytocin
      2. Releases many stimulating and inhibitory hormones that regulate anterior pituitary hormone release
4. Limbic system - on the border of diencephalon and cerebrum
   1. Functional grouping of structures from cerebrum, diencephalon and midbrain
   2. Memory processing, creates emotional states and related behavioral drives
      1. Amygdaloid body - involved in “fight or flight” response, links emotions with specific memories
      2. Hippocampus - in learning, storage and retrieval of new long-term memories, location of neurogenesis, area affected by Alzheimer’s
      3. Mamillary bodies - process olfactory information

Cerebrum - largest region

• Divided into two hemispheres which are subdivided into lobes
  • Each hemisphere controls motor functions of opposite side of body
  • Hemispheres anatomically similar but functionally different
• Outer cortex of gray matter folded into gyri with deep fissures and shallow grooves (sulci), increases surface area in a species-specific pattern
• Inner medulla composed of white matter, tracts
  • Association fibers - connects portions of same hemisphere
  • Commissural fibers - interconnect two hemispheres; ex. corpus callosum
  • Projection fibers - project into or out of the cortex, forms internal capsule

1. Basal nuclei - masses of gray matter embedded in medulla, areas of synapse
   1. Caudate nucleus, lentiform nucleus, globus pallidus, putamen, striatum
   2. Input and output between nuclei and the thalamus and then to cerebral cortex
   3. Subconscious control of muscle tone, does not initiate movements but coordinates learned muscle patterns and rhythms
   4. Interval timer: Spiny striatal cells receive input from thousands of cortical oscillator cells with different firing frequencies. Stimulus event causes all oscillator cells to start firing at same time. Striatal cells record the unique pattern of firing at end of event. When stimulus happens again, it initiates striatal cell monitoring and dopamine release to start interval timer
2. Major sensory and motor areas of cortex - central sulcus separates sensory and motor areas
   1. Primary motor cortex - surface of precentral gyrus, voluntary motor control, fine movements of specific muscle groups
   2. Premotor cortex - association area, patterns of learned motor responses of sequential nature
   3. Prefrontal area - many associations with other cortical areas, interprets and predicts, long-term planning and concentration; tension, anxiety and frustration arise here
   4. Motor speech center (Broca’s) - coordinates larynx and mouth for speech, develops in 1 hemisphere
   5. General interpretive area (Wernicke’s) - integrates sensory information with visual and auditory memories, only develops in one hemisphere
   6. Primary sensory cortex - postcentral gyrus, input from somatic sensory receptors, localizes origin of sensation on body
   7. Primary visual cortex - visual information concerning shape, color and movement
   8. Primary auditory cortex - basic characteristics of sound, e.g. pitch and rhythm
3. Hemispheric lateralization - functional differences in two hemispheres
   1. Left - language, speech, writing, mathematics, interpretation, reasoning
   2. Right - music, artistic skills, spatial skills, imagination and insight, emotional context