Lesion of the Visual System Flashcards
What do you find in the optic nerve?
Fibers from one eye
In the optic tract, what do you find?
Fibers from both eyes
The right visual hemifield is projected where?
R eye Nasal Retina
L eye Temporal retina
The left visual hemifield is projected where?
L eye Nasal retina
R eye temporal retina
Where do the retinal ganglion cells project?
to the lateral geniculate body (nucleus of the thalamus)
Where does the lateral geniculate nucleus project to?
Primary Visual Cortex V1 via the optic radiations
What do the fibers of the optic radiations pass when going to the occipital cortex?
lateral ventricle
Meyer’s loop
fibers transmiting from inferior retina -> inferior bank of calcarine fissure (lingual hyrus)
Fibers relaying information from the superior part of the retina terminate where?
Superior bank of the calcarine fissure (cuneus gyrus)
The blood supply to the visual system comes from where?
Opthalmic artery
Middle cerebral arteries
Posterior cerebral arteries
Lesion of the optic nerve?
Complete blindness in the respective eye
(also affects 3-D vision = stereopsis)
Monocular blindness
A sagittal transection of the optic chiasm causes what?
loss of input from the bitemporal visual hemifields
bitemporal hemianopsia
*Pituitary gland tumor
Transverse transection of the optic chiasm would cause what?
blindness in both eyes
Lesion of the optic tract, lateral geniculate nucleus, and the entire optic radiation would cause?
homonymous hemianopsia
loss of visual input from entire hemifield
Lesion of the optic tract and lateral geniculate
Complete homonymous hemianopsia
Optic radiation fiber loss causes what?
Partial hemianopsia
unilateral lesion in the temporal lobe affecting Meyer’s loop provokes?
Visual deficits in the superior quadrant of the contralateral visual hemifiels
Upper contralateral quadrantic anopsia
A lesion in the inferior bamk of the calcarine sulcu (lingual gyrus) will cause?
Also the Meyer’s loop sooooo
Loss of Superior quadrant of the contralateral hemifield
Lesion of the upper bank of the calcarine sulcus (cuneus gyrus) affects?
Information coming from the superior half of the retina, and consequentially = deficits inthe contralateral inferior quadrant of the visual hemifield
If a lesion involves a larger region of the primary visual cortex what happens
Both banks of the calcarine sulcus affected
Contralateral homonymous hemianopsia
The primary visual cortex is typically supplied by the?
Posterior cerebral artery
and
Middle cerebral artery
Because of dual blood supply to the primary visual cortex what happens?
fovea sparing (macula cortical representation)
After the calcarine fissure where do the fibers go?
They eneter the the so-caled extra-strieate cortices and split into ventral (temporal) and dorsal stream (parietal).
The ventral stream recieves input from?
both magno- and parvovellular retinal ganglion cell system
Object Vision
The dorsal stream recieves input from?
magnocellular system
Movement detection and spatial orientation
Lesion in the occipital cortex can cause?
Partial deficits of visual processing, following destruction of V4
achromatopsy
Patients cannot distinguish color
Lesion of Area V5 (MT/MST) provokes what?
Significant reduction in the perception of motion
akinematopsy
total loss of experiencing moving objects as moving
(saccade like displacements)
Lesion in the temporal lobe and TPO border may provike?
deficit in object perception while vision is preserved
agnosia
can’t identify object by vision but can by touch or sound
Lesion of the left occipital lobe causes?
prosopagnosia
loss of the ability to recognize faces
(subset of agnosia)
Lesion of the left occipital cortex or of the angular gyrus caused?
alexia
loss of the ability to read
(subset of agnosia)
Partial lesion of the right temporal lobe leads to?
The inability to gage the emotional content of facial expression
Lesion of the Right Parietal lobe or the parietal temporal border leads to?
Spatial hemineglect
patients ignore entire left visual world although there is a transmission of information from the retina to the visual cortex
Explore the lost world by eye or head movement just like hemianopsia patients
Most frequenct neurological symptom after stroke and seizures
What can restitute function after spatial hemineglect?
Caloric or galvanic vestibular stimulation
During spatial hemineglect what does the lesion actually disturb?
internal spatial coordinate frame
temporarily “off center”
Balint syndrome is caused by?
Bilateral temporal lesion
spatial temporal disorientation, generalized loss of attention, combining paralysis of visual fixation, optic ataxia, and impairment of visual fixation, inability to execute voluntary movement in response to visual stimuli
