Visual system Flashcards
definition: prosopagnosia
difficulty identifying faces
definition: scotoma
visual field defect
which receptor mediates scotopic vision?
rods
which receptor mediates photopic vision?
cones
which retinal cell type can produce an action potential?
ganglion cells
which retinal cells are output cells?
ganglion cells
which retinal cells capture photons?
ganglion cells
what is the function of retinal projections to the suprachiasmatic nuclei?
circadian rhythms
what is the function of retinal projections to the pretectal nuclei?
meidates pupillary light reflexes
what is the function of retinal projections to the LGN?
relays to visual cortex and receives input from visual cortex (90% of retinal axons terminate here)
what is the function of retinal projections to the superior colliculi?
in response to visual (or auditory or somatic) stimuli can cause eyes, head, and even body to turn toward stimuli
what is the function of the dorsal visual stream to higher visual areas? ventral stream?
- dorsal - analysis of motion and relative positions of objects in visual scene - selectivity for direction and speed of movement 2. ventral - high level form vision and object recognition - selectivity for shape, color, and texture
what is the clinical significance of having different pathways for different aspects of vision?
restricted cortical lesions result in different types of selective visual deficits - can result in prosopagnosia or object agnosia
what is the location of the genes for the cone pigments?
- red and green - X chromosome 2. blue - chromosome 7 3. rhodopsin - chromosome 3
which mechanisms of depth perception are monocular? which require vision in both eyes?
- monocular - size and motion 2. binocular - stereoscopic
deficiency of which vitamin can cause night blindness?
vitamin A
the ciliary muscle contracts in response to what type of autonomic innervation?
parasympathetic
definition: receptive field of a neuron
area of retina from which the neuron can be influenced
what is the result of a lesion to the central part of the optic chiasm?
bitemporal hemianopsia
what is the result of a lesion to the optic tract?
homonymous hemianopsia
what is the result of a lesion to Meyer’s loop?
superior quadrant anopsia contralateral to lesion
