Visual system part 2 Flashcards
ant; post in primary visual cortex
Peripheral vision; Central vision
expanded cortical representation
Central vision
goes through macula
and has expanded cortical representation
Central vision
most area 17 neurons have a preference for input
from one eye)(monocular)
Axons from LGN course to the primary visual cortex (area 17) and synapse on
layer IV neurons.
monocular; binocular
Layer IV neurons; Layer II/III, V and VI neurons
simple and complex cell
area 17
orientation of a line.
simple cell
may be direction sensitive or respond best to a corner, cross or x.
Complex cells
Cell column that prefer the same line orientation
Orientation Column
Cell clusters that respond to color
Color-Sensitive Region
wavelength sensitive
Color-Sensitive Region
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
Hypercolumn
refer to a set of orientation and ocular dominance columns that receive input from a given point in the visual field
Primary visual cortex
projects to extrastriate visual areas where neurons require complex stimuli for maximal activation
Primary visual cortex respond to
fundamental aspect of a visual stimulus (orientation, contrast, motion, color, eye of origin)
Dorsal (“M”) Stream
where
perception of motion
posterior parietal association cortex
(from Dorsal (“M”) Stream)
visual information travels to the inferior temporal association cortex
Ventral (“P”) Stream
Ventral (“P”) Stream
what
size, shape, color, orientation
inferior temporal association cortex
(Ventral (“P”) Stream)
inferior temporal cortex
Lesion to V4
Lesion to V1
Scotoma (bind spot)
Lesion to V5
parietal pathway
achromatopsia
color recognition
(Lesion to V4 à inferior temporal cortex)
object recognition
(agnosia)
(• Lesion to V4)
face recognition
prosapagnosia
(fusiform face area)
(Lesion to V4)
Projections to the superior colliculus play a role in
visual orientating reflexes
head to visual stimuli
Tectospinal Tract
Tectospinal Tract
contralat
sphincter pupillae
innervated by Postganglionic parasympathetic fibers
Preganglionic parasympathetic fibers (travel with CN III)
to ciliary ganglion
tf from the pretectal nucleus travel bilaterally to Edinger-Westphal Nucleus
in Pupillary Light Reflex
t
TF in the Pupillary Light Reflex the Temporal optic fibers innervate ipsilateral pretectal area
T
Edinger-Westphal Nucleus
Pupillary Light Reflex
Ø Pretectal area bilaterally innervates
Edinger-Westphal nucleus (EWN)
Pupillary Light Reflex
Fibers from EWN travel to the ipsilateral ciliary ganglion via
CN 3
Pupillary Light Reflex
short ciliary nerves
Fibers from the ciliary ganglion travel to the ipsilateral eye
Pupillary Light Reflex
pupillary constrictor
Pupillary Light Reflex
Your patient presents with blindness in the right eye. Where is the lesion?
right retina or right optic nerve
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
direct pupillary light reflex
Illuminated eye—
—consensual pupillary light reflex
ØNon-illuminated eye
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)
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
Light directed to either eye causes
bilateral constriction of the pupils
in Pupillary Light Reflex
Damage to the midline fibers of the optic chiasm may be caused by a
pituitary tumor.
right homonymous hemianopia means that there is
loss of vision in the right visual field
