2. There are 4 stages of non rapid eye movement (NREM) sleep.  Then there
       is REM sleep, this is when we dream.

  3. The electroencephalogram (EEG) is often used to study sleep.
    A. EEG represents the summed postsynaptic activity of cerebral neurons.

  4. The following are EEG waves
    A. Beta waves occur when a person is alert and aroused.

    B. Alpha waves occur when a person is resting quietly
 
    C. Theta waves: occur in the transition between sleep & wakefulness.

    D. Delta waves become more frequent during deep sleep (stages 3 and 4)
 

II. Stages of sleep
1. NREM:
  A. Stage 1: some alpha & theta activity
  B. Stage 2 no alpha activity but some theta waves (mixed EEG)
    a. We also see  sleep spindles (pointed waves) and K complexes

  C. Stage 3: delta waves occur more frequently
  D. State 4: delta waves predominate.
 

2. REM sleep (paradoxical sleep):
  A. The heart rate, cerebral blood flow (especially in the cerebral cortex), and
        breathing resemble that of an awake person.
  B. The EEG has theta & beta activity (more like an awake person).

  C. Most REM sleep occurs toward the end of the nights sleep
  D. REM deprivation benefits some depressed people

III. Why do we Sleep?
1. Sleep as circadian rhythm:
   A. Thus, many have proposed an internal clock in the suprachiasmatic
         nucleus (SCN) of the hypothalamus.

2. survival value: i.e., to conserve energy & stay away from predators.

3. Sleep may restore us:

4. REM sleep: may be important for neuronal upkeep & learning
 

IV. Sleep Disorders:
1 insomnia: feeling tired during the day due to trouble falling asleep or
   staying asleep

2. Narcolepsy: a disorder where suffers switch from active waking states to
   several minutes of REM sleep (loss of muscle tone)

3. sleep apnea: a sleeper stops breathing many times during the night
  A. they often do not feel rested but do not remember any problems
  B. apparently there are 2 types
    a. central sleep apnea: diminished CNS respiratory drive
    b. obstructive sleep apnea: caused by relaxation of the pharyngeal muscle

  C. Sudden Infant Death Syndrome: This may be a type of sleep apnea

4. nightmares: these are frightening dreams in REM sleep

5. night terrors: these are horrific non-REM images occurring during stage 4

6. sleepwalking: this usually occurs in non-REM sleep

7. REM behavior disorder (REM without Atonia): the near paralysis that
    should accompany REM sleep is absent and the person appears to act out
    their dreams
 
 

  A. punch-drunk syndrome (dementia pugilistica): caused by repeated
      Concussions
  B. don’t confuse this term with contusion: are internal hemorrhaging or a
       hematoma (brain bruise)
    a. brain slams against the inside of the skull

2. coma: when you can not be aroused by sensory stimuli
  A. different from sleep

  B. caused by CNS trauma: e.g., hypoxia, toxins, hypoglycemia, ion
       imbalances, etc.

3. vegetative state: no communication between brainstem & cerebrum
  A. it is my understanding that coma usually turns into this
  B. cranial nerve reflexes are preserved

4. brain dead: absence of function of the brainstem
 

II. What types of brain injury cause these abnormal states
1. cortical damage alone usually does not cause this unless the lesion is big
2. small lesions to certain areas of the thalamus can
3. small lesions to certain areas of the brainstem can
4. intracranial pressure (e.g., caused by increased CSF, tumors, & swelling
    from head injury) can push brain tissue around & compress axons
  A. swelling can force part of the uncus & hippocampus thru the tentorial
      notch (Kingsley p. 534)

  B. swelling can also force the lower brainstem & cerebellar tonsils into the
       foramen magnum
    a. this restricts cardio & respiratory centers
 

III. Seizures: refers to episodes of abnormal neural excitement
 1. epilepsy: is characterized by repeated seizure thru out life

 2. two basic types of seizures
   A. partial seizures: initiated in 1 part of the brain
      a. area where they are initiated is called the focus

   B. general seizures: involve the entire brain immediately (two types)
      a. absence seizures: lose awareness without loss of muscle tone

      b. tonic-clonic seizures: person loses consciousness, falls, body stiffens

 3. causes of seizures
 

 1.  Damage to the left hemisphere is more often associated with loss of
       control of language (Broca noticed this in 1861).

 2. Sperry and coworkers severed the corpus callosum to reduce the severity of
     epileptic seizures in some individuals (split-brain subjects)

 3. in summary results from dominance research indicates
    A. left hemisphere specializes in verbal processing (i.e., speech, reading, &
         writing) & tasks that require logic
    B. right hemisphere is superior in some tasks;

 4. some have suggested that women may often have brains that are less
     specialized, thus, they have better recovery after brain damage (i.e., other
     brain areas take over)

 3. anomic aphasia: fluent speech but you can not find the words

 4. alexia: loss of ability to read
  A. dyslexia: is an incomplete alexia
    a. peculiarities in the planum temporale (area 22) are sometimes observed
 

II. cortical neglect (asomatognosia): often after damage to SS association
     cortex (parietal lobe) usually on the nonspeaking side
 

III, disorders of personality with frontal lobe damage (prefrontal lobe
      syndrome)
 1. Phineas Gage: had a rod blown thru his head (damaging the anterior part of
      both frontal  lobes).

 2.  prefrontal lobotomy (leukotomy)
  A. projections fibers connecting the thalamus & orbital cortex were severed
    a. Moniz won a nobel prize for his work in this area in 1949

 
3. prefrontal damage (anterior to Brodmans area 6) results in
  A. personality changes: sexually uninhibited, lack compassion, display poor
       social skills (e.g., wet or soil themselves, tell hurtful jokes)
  B. perseveration: repeating an action or response

  C. infantile reflexes come back e.g., rooting

  D. anosognosia: patient is not consciously aware of paralysis, some other
      physical disability (e.g., blindness), or cognitive impairment
 

IV. Dementia: refers to permanent loss of higher order functioning (memory
       personality, language): examples include
 1. Alzheimer's disease is the most common cause
  A. the following cellular abnormalities are noted
    a. lots of cells in the cortex (hippocampus to) die & the cortex thins
     ?fissures & sulci get wider

    b. senile or neuritic plaques are abundant

    c. neurofibrillary bodies (tangles): disorganized knots of neurofilaments

  B. symptoms are progressive
 

 2. dementia secondary to vascular disease (i.e., stroke) is also common
 
 3. general paralysis (paresis) of the insane: effects the prefrontal area
  A. occurs when syphilis has affected the CNS

 4. Korsakoff's disease: usually associated with chronic alcohol use &
     thiamin deficiency
   A. neuron death observed in thalamus & hypothalamus

 5. Creutzfeldt-Jakob disease (a type of spongiform encephalopathy)
  A. cause is unknown maybe a virus or prion (abnormal protein)

 6. Huntington's disease produces dementia also (discussed earlier)

 7. rabies (Latin for rage) is caused by a virus that attacks much of the brain
     but particularly the temporal lobe (limbic structures are here)
   A. leads to furious violent behavior and as I recall problems drinking

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