Visual system part 2 Flashcards Preview

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Flashcards in Visual system part 2 Deck (50):
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ant; post in primary visual cortex

Peripheral vision; Central vision

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expanded cortical representation

Central vision

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goes through macula

and has expanded cortical representation

 Central vision

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most area 17 neurons have a preference for input

from one eye)(monocular)

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Axons from LGN course to the primary visual cortex (area 17) and synapse on

layer IV neurons.

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monocular; binocular

Layer IV neurons; Layer II/III, V and VI neurons

 

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simple and complex cell

area 17

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orientation of a line.

simple cell

 

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may be direction sensitive or respond best to a corner, cross or x.

Complex cells

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Cell column that prefer the same line orientation

Orientation Column

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Cell clusters that respond to color

Color-Sensitive Region

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wavelength sensitive

Color-Sensitive Region

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Cell column that respond to input from either the R or L eye OR in the case of binocular cell, have a strong preference for the R or L eye

Ø Ocular Dominance Column

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Hypercolumn

refer to a set of orientation and ocular dominance columns that receive input from a given point in the visual field

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Primary visual cortex

projects to extrastriate visual areas where neurons require complex stimuli for maximal activation

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Primary visual cortex respond to 

fundamental aspect of a visual stimulus (orientation, contrast, motion, color, eye of origin)

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Dorsal (“M”) Stream

where

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perception of motion

posterior parietal association cortex

(from Dorsal (“M”) Stream)

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visual information travels to the inferior temporal association cortex

Ventral (“P”) Stream

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Ventral (“P”) Stream

what

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size, shape, color, orientation

inferior temporal association cortex

(Ventral (“P”) Stream)

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inferior temporal cortex

Lesion to V4 

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Lesion to V1

Scotoma (bind spot)

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Lesion to V5 

parietal pathway

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achromatopsia

color recognition

(Lesion to V4 à inferior temporal cortex)

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object recognition

(agnosia)

(• Lesion to V4)

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face recognition

prosapagnosia

(fusiform face area)

(Lesion to V4)

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Projections to the superior colliculus play a role in

visual orientating reflexes

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head to visual stimuli

Tectospinal Tract

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Tectospinal Tract

contralat

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sphincter pupillae

innervated by Postganglionic parasympathetic fibers

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Preganglionic parasympathetic fibers (travel with CN III)

to ciliary ganglion

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tf from the pretectal nucleus travel bilaterally to Edinger-Westphal Nucleus

in Pupillary Light Reflex

t

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TF  in the Pupillary Light Reflex the Temporal optic fibers innervate ipsilateral pretectal area

T

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Edinger-Westphal Nucleus

Pupillary Light Reflex

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Ø Pretectal area bilaterally innervates

Edinger-Westphal nucleus (EWN)

Pupillary Light Reflex

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Fibers from EWN travel to the ipsilateral ciliary ganglion via  

CN 3

Pupillary Light Reflex

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short ciliary nerves

Fibers from the ciliary ganglion travel to the ipsilateral eye

 

 

Pupillary Light Reflex

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pupillary constrictor

Pupillary Light Reflex

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Your patient presents with blindness in the right eye. Where is the lesion?

right retina or right optic nerve

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bitemporal hemianopia/hemianopsia

Hemianopia/hemianopsia - loss of half of a visual field. Bitemporal hemianopia means that there is loss of vision in both the right and left temporal visual fields

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direct pupillary light reflex

Illuminated eye—

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—consensual pupillary light reflex

ØNon-illuminated eye

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right homonymous hemianopsia

Lesion to the left optic tract Lesion to the left LGN Lesion to the left optic radiations Complete lesion to the left primary visual cortex (area 17, V1)

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papillary light reflex, you shine a light in your patient’s right eye. You note that the right pupil constricts, but the left pupil remains unchanged.

left Edinger Westphal nucleus 

left CN-III 

left ciliary ganglion

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Light directed to either eye causes

bilateral constriction of the pupils

in Pupillary Light Reflex

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Damage to the midline fibers of the optic chiasm may be caused by a

pituitary tumor.

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right homonymous hemianopia means that there is

loss of vision in the right visual field