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note 05 - visual and motor systems

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Ted Petit

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Lec 5
visual system anatomy
retina divided into two portions from middle
-nasal portion: retina near the nose
-temporal portion: retina away from the nose
optic nerve --> optic chiasm --> optic tract (nerves in CNS)
-nerves from temporal portion run to ipsilateral cortex while nerves from nasal portion go across
to contralateral cortex
-object from right visual filed will 'hit' Nasal portion of RIGHT eye and Temporal portion of
LEFT eye, then info of the object will reach to Left visual cortex
-primary visual cortex(17): receive info from eyes
-associational visual cortex: recognize objects faces ...
problems of visual info transmission
optic nerve damage--
-nomocular blindness: damage of one eye, lose vision from that eye
-bitemporal hemianopia: damage of optic chiasm (nerves from nasal), lose two lateral Visual field
primary cortex damage (info receiving problems)--
-partial occipital cortex damage of one side causes blindness on opposite visual field
-macular sparing: complete damage of one side cortex causes b lindness on opposite visual field
except center spot
associational cortex damage (higher order problems)--
-visual agnosia: inability to recognize what objects are
-prosopagnosia: inability to recognize/distinguish FACES and other comlex visual stimuli (damage
in area 18&19 )
-color agnosia: color seems less intense to patients after stroke (bilateral damage of occipital
temporal region)
somatosensory system problem
(recall: primary sensory cortex - postcentral gyrus)
-influence sensory threshold
-stereognosis: impairment of judging shapes of objects using hands, locating spatial objects
(especially patients' own limbs)
motor system problem
-generally involves primary mortor cortex (precentral gyrus) damage
-severe stroke can damage motor cortex
-f lacid paralysis(limbs hang down) may turn to hypertonic paralysis(rigid limbs) within few
-mild stroke disrupt fine motor movement (particularly fingers move)
-apraxia: inability to perform appropriate complex movement with objects
Parkinson's disease--
-common among 60-70y but does affect young people
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