Lesion of the Visual System

Question 1

What do you find in the optic nerve?

Answer 1

Fibers from one eye

Question 2

In the optic tract, what do you find?

Answer 2

Fibers from both eyes

Question 3

The right visual hemifield is projected where?

Answer 3

R eye Nasal Retina

L eye Temporal retina

Question 4

The left visual hemifield is projected where?

Answer 4

L eye Nasal retina

R eye temporal retina

Question 5

Where do the retinal ganglion cells project?

Answer 5

to the lateral geniculate body (nucleus of the thalamus)

Question 6

Where does the lateral geniculate nucleus project to?

Answer 6

Primary Visual Cortex V1 via the optic radiations

Question 7

What do the fibers of the optic radiations pass when going to the occipital cortex?

Answer 7

lateral ventricle

Question 8

Meyer’s loop

Answer 8

fibers transmiting from inferior retina -> inferior bank of calcarine fissure (lingual hyrus)

Question 9

Fibers relaying information from the superior part of the retina terminate where?

Answer 9

Superior bank of the calcarine fissure (cuneus gyrus)

Question 10

The blood supply to the visual system comes from where?

Answer 10

Opthalmic artery

Middle cerebral arteries

Posterior cerebral arteries

Question 11

Lesion of the optic nerve?

Answer 11

Complete blindness in the respective eye

(also affects 3-D vision = stereopsis)

Monocular blindness

Question 12

A sagittal transection of the optic chiasm causes what?

Answer 12

loss of input from the bitemporal visual hemifields

bitemporal hemianopsia

*Pituitary gland tumor

Question 13

Transverse transection of the optic chiasm would cause what?

Answer 13

blindness in both eyes

Question 14

Lesion of the optic tract, lateral geniculate nucleus, and the entire optic radiation would cause?

Answer 14

homonymous hemianopsia

loss of visual input from entire hemifield

Question 15

Lesion of the optic tract and lateral geniculate

Answer 15

Complete homonymous hemianopsia

Question 16

Optic radiation fiber loss causes what?

Answer 16

Partial hemianopsia

Question 17

unilateral lesion in the temporal lobe affecting Meyer’s loop provokes?

Answer 17

Visual deficits in the superior quadrant of the contralateral visual hemifiels

Upper contralateral quadrantic anopsia

Question 18

A lesion in the inferior bamk of the calcarine sulcu (lingual gyrus) will cause?

Answer 18

Also the Meyer’s loop sooooo

Loss of Superior quadrant of the contralateral hemifield

Question 19

Lesion of the upper bank of the calcarine sulcus (cuneus gyrus) affects?

Answer 19

Information coming from the superior half of the retina, and consequentially = deficits inthe contralateral inferior quadrant of the visual hemifield

Question 20

If a lesion involves a larger region of the primary visual cortex what happens

Answer 20

Both banks of the calcarine sulcus affected

Contralateral homonymous hemianopsia

Question 21

The primary visual cortex is typically supplied by the?

Answer 21

Posterior cerebral artery

and

Middle cerebral artery

Question 22

Because of dual blood supply to the primary visual cortex what happens?

Answer 22

fovea sparing (macula cortical representation)

Question 23

After the calcarine fissure where do the fibers go?

Answer 23

They eneter the the so-caled extra-strieate cortices and split into ventral (temporal) and dorsal stream (parietal).

Question 24

The ventral stream recieves input from?

Answer 24

both magno- and parvovellular retinal ganglion cell system

Object Vision

Question 25

The dorsal stream recieves input from?

Answer 25

magnocellular system ## Footnote **Movement detection and spatial orientation**

Question 26

Lesion in the occipital cortex can cause?

Answer 26

Partial deficits of visual processing, following destruction of V4 **achromatopsy** Patients cannot distinguish color

Question 27

Lesion of Area V5 (MT/MST) provokes what?

Answer 27

Significant reduction in the perception of motion **akinematopsy** total loss of experiencing moving objects as moving (saccade like displacements)

Question 28

Lesion in the temporal lobe and TPO border may provike?

Answer 28

deficit in object perception while vision is preserved **agnosia** can't identify object by vision but can by touch or sound

Question 29

Lesion of the left occipital lobe causes?

Answer 29

**prosopagnosia** loss of the ability to recognize faces (subset of agnosia)

Question 30

Lesion of the left occipital cortex or of the angular gyrus caused?

Answer 30

**alexia** loss of the ability to read (subset of agnosia)

Question 31

Partial lesion of the right temporal lobe leads to?

Answer 31

The inability to gage the emotional content of facial expression

Question 32

Lesion of the Right Parietal lobe or the parietal temporal border leads to?

Answer 32

**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_

Question 33

What can restitute function after spatial hemineglect?

Answer 33

Caloric or galvanic vestibular stimulation

Question 34

During spatial hemineglect what does the lesion actually disturb?

Answer 34

internal spatial coordinate frame temporarily "off center"

Question 35

Balint syndrome is caused by?

Answer 35

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