Physiology of the Visual System Flashcards
What structure provides the first site for refraction?
Cornea
What is the action of the ciliary muscle and suspensory ligaments to create a round lens?
Ciliary muscle contracts
Suspensory ligaments loosen
(Near vision)
What is the action of the ciliary muscles and the suspensory ligaments to create a flatter lens?
Ciliary muscle relaxes
Suspensory ligament tightens
(Far vision)
Which retinal cells are horizontally oriented?
Horizontal cells
Amacrine cells
Which retinal cells are vertically oriented?
Receptor cells (Rods and cones)
Bipolar cells
Ganglion cells
In the retina, where are rods most abundant? Where are cones most abundant?
Rods - Just off center
Cones - Directly center (fovea)
What NT is released by rods/cones?
Glutamate
What visual conditions cause higher glutamate release?
Darkness (rods/cones are NOT inhibited by photons)
What visual conditions cause lower glutamate release?
Bright light
(Rods/cones hyperpolarize when stimulated by photons)
What is the receptor that glutamate is binding in the cone photoreceptors?
Gi GPCR
What receptor would be activated by glutamate in an Off-Center cone cell?
AMPA kainate
What NT causes depolarization of a ganglion cell?
Glutamate
In activation of a rod photoreceptor, what cell acts as an interneuron between bipolar cells? What NT is released?
Amacrine cell
GABA or glycine (inhibitory)
What structure is associated with the response to move eyes into an intended position? (Movement intention)
Superior colliculus
What tract is associated with the superior colliculus?
Tectospinal
What visual structure is important for converging and controlling eye motion onto a point of interest and mapping it in space, as well as movement relative to that object?
Lateral Geniculate body
What Broadmann area is associated with the parastriate cortex? Peristriate cortex?
Parastriate - 18
Peristriate - 19
(Primary visual cortex - 17, dead center)
What retinal cell layers make up V1?
I, II, III, IV
What is the main input layer for V1? What structure does it receive from?
Layer IV
LGB
What are the main output layers for V1? What structures do they send information to?
V and VI
LGB, thalamus, subcortical regions
What type of input do ocular dominance columns respond to?
Input from one eye or the other
What type of input do the orientation columns respond to?
Visual line stimuli of varying angles
What type of input are the blobs of the primary visual cortex responsive to?
Specific wavelengths on the color absorption spectra associated with a specific cone (Red, green, blue)
What is the major function of V1?
Identify edges, contours of objects
