PSYC 415 -- Study Points for General Effects of Brain Damage (revised 29 August 2020)

Frontal Lobe Lesions - exact character depends on location of lesion; posterior
   lesions (in the motor areas) result in movement disorders; anterior lesions
   (in the prefrontal cortex) result in much more complex changes
1) disturbances of motor function and movement programming up to and including
   hemiplegia (upper motor neuron disease)
2) disturbances of voluntary gaze (patients don't "look at the right places" to
   answer questions)
3) speech production - Broca's aphasia (Broca's area and supplementary speech
   area in left hemisphere)
4) disturbance in intelligence
   a) but not in IQ test taking ability - convergent thinking (just one answer)
   b) divergent thinking impaired - ability to come up with multiple answers
   c) failure of abstract thinking - concrete thinking
5) loss of behavioral spontaneity
6) impaired strategy formation and decision making - esp. in novel situations
7) impaired response inhibition, perseveration
8) distractibility and poor attention
9) failure to comply with instructions, rule breaking, risk taking, failure to
   learn from experience (impulsiveness)
10) impaired autobiographical memory - e.g., patients can remember going to HS,
   they can tell what HS was like, but they can't relate personal stories
   about HS
11) impaired social and sexual behavior - personality changes
    a) pseudodepression - apathy, indifference, loss of initiative, reduced
       sexual interest, reduced verbal output (more common w/left hemis. damage)
    b) pseudopsychopathy - immature behavior, lack of tact and restraint,
       profanity, promiscuity, lack of social grace (often said to be more
       common with right hemis. damage, but may be due to damage in the
       orbitofrontal cortex)

Temporal Lobe Lesions
1) disturbances in auditory sensation and perception
   a) difficulty discriminating speech sounds and "tone of voice" (prosody)
   b) difficulty with music perception
   c) auditory hallucinations - due to spontaneous activity in auditory cx.
2) Wernicke's aphasia - inability to produce or comprehend meaningful speech
   (damage to left posterior superior temporal gyrus)
3) disturbances in visual perception - visual agnosia, prosopagnosia
4) anterograde amnesia (due to ventral temporal and hippocampal damage)
5) affective changes - perhaps due to involvement of amygdala and limbic cx.
6) temporal lobe personality (very few patients display all of this syndrome) -
   sometimes seen in temporal lobe epilepsy (Geschwind)
   a) overemphasis on trivia and petty details of daily life
   b) pedantic speech and egocentricity
   c) "stickiness" - person persists in discussing personal problems, and you
      "get stuck listening to him"
   d) paranoia
   e) obsessive preoccupation with religion
   f) proneness to aggressive outbursts
   g) hypersexuality

Occipital Lobe Lesions
1) blindness for part or all of the visual field - cortical blindness
2) visual agnosia - failure of object recognition (occipitotemporal)
3) visuospatial agnosia - topographical disorientation (occipitoparietal)
4) prosopagnosia - facial agnosia (including for their own faces)
5) alexia - inability to read (left hemis. damage)
6) failure of visual imagery (imagination)

Parietal Lobe Lesions
1) somatoperceptual disorders - e.g., loss of tactile sensation, astereognosia
   (inability to recognize objects by touch), asomatognosia (loss of body sense
   and condition)
2) contralateral neglect (esp. after right hemisphere damage)
3) optic ataxia - failure of visually guided movements
4) apraxia - a peculiar loss of skilled movements in response to directions
   (esp. after left hemisphere damage, but some forms after right as well; a
   "disconnection syndrome")
5) failure of spatial cognition - e.g., mental rotation
6) impaired IQ testing ability - failure of convergent thinking
7) agraphia - inability to write (left hemisphere damage)
8) acalculia - inability to do arithmetic (left hemisphere damage)
9) right-left confusion (esp. after left hemisphere damage)
10) language disturbances - alexia and aphasia (left hemisphere damage)
    a) angular gyrus
    b) relay of auditory and visual info to language processing areas

Basal Ganglia Lesions
1) movement disorders
   a) akinesia - no movement
   b) bradykinesia - slowed movement
   c) hypokinesia - deficiency in movement (includes a and b)
   d) dyskinesia - abnormal involuntary movements
      i) athetosis - slow writhing movements, esp. in the hands
      ii) chorea (coreiform movements) - rapid jerky movements
      iii) dystonia - writhing movements often involving large parts of the
            body, resulting in strange postures and body positions
   e) hyperkinesia - too much movement (includes d)
2) tremor
   a) essential (familial) tremor
   b) drug-induced
   c) resting tremor - as in Parkinson's disease
   d) intention tremor - more characteristic of cerebellar damage
3) palsy
4) tics - as in Tourette's disease
5) obsessions and compulsions

Limbic System Lesions
1) hippocampus
   a) seizures
   b) anterograde amnesia
   c) disorientation (loss of spatial memory)
2) amygdala
   a) emotional changes - particularly a loss of fear responses
   b) changes in social behavior - overfriendliness, inappropriate comments,
      lack of awareness of personal space (observed in S.M.)
   c) lesions in the amygdala produced by Herpes Simplex Encephalitis

Lesions to the Thalamus - thalamic syndrome
1) loss of all somatosensory modalities including pain (VPL and VPM)
2) hyperalgesia - painful sensation resulting from mild stimulation of the skin
   (seen once the patient begins to recover from 1)
3) partial blindness (LGN) or auditory deficits (MGN)
4) movement disorders of the type caused by cerebellar and basal ganglia damage
   (both of which relay through the thalamus) - ataxia, tremor, choreoathetosis
5) amnesia (Korsakoff's syndrome)

Lesions to the Hypothalamus
1) endocrine disturbances similar to the those caused by pituitary tumors
   (hypogonadism - undersecretion of sex hormones; diabetes insipidus (not due
   to kidney damage) - inability to conserve water, excessive thirst;
   precocious puberty in young people, or impotence in adults)
2) visual disturbances can occur if a tumor in the hypothalamus compresses the
   optic tracts, which lie just ventral to the hypothalamus (often the first
   sign of a hypothalamic tumor)
3) weight change (loss or gain) - gross overeating and obesity, or cachexia
4) signs of dysregulation of autonomic NS - excessive sweating, nervousness,
   irritability, shakiness, etc., and signs of low adrenal function such as
   dizziness and weakness
5) failure of body temperature regulation
6) sleep disturbances
7) disturbances in circadian rhythms
8) changes in mood and emotion
9) amnesia (Korsakoff's syndrome)

Cerebellar Lesions
1) ataxia - loss of coordination and equilibrium
2) tremor (usually intention tremor)

Brainstem Lesions
1) loss of consciousness - coma
2) loss of heart or respiratory function - death
3) sensory or motor deficits if those structures or pathways are damaged
4) deficits associated with cranial nerve impairment