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visual pathways
visual pathways and processing
| Question | Answer |
|---|---|
| the retina develops from what? | an outpouching of the prosencephalon |
| what are the five major neuronal cell types of the retina? | photoreceptor cells, horizontal cell, bipolar cell layer, ganglion cell layer, amacrine cell |
| which part of the eye has the highest visual acuity? | fovea |
| what is the direction of light flow from cornea to retina? | nerve fiber layer, ganglion cell layer, inner plexiform layer, inner nuclear layer, outer plexiform layer, outer nuclear layer, layer of rods and cones |
| what is the direction of information flow in the retina? | layer of rods and cones, outer nuclear layer, outer plexiform layer, inner nuclear layer, inner plexiform layer, ganglion layer, nerve fiber layer |
| what type of wavelength do S cones absorb? | short wavelength (blue) |
| what type of wavelength do M cones absorb? | intermediate wavelength (green) |
| what type of wavelength do L cones absorb | long wavelength (red |
| how is the retina specialized? | regionally |
| is the central fovea vascular or avascular? | avascular |
| why is the fovea the center for highest visual acuity? | it has a lot of rods |
| in what orientation is an image projected onto the retina? | upside down and backwards due to the refraction of light through a convex lens |
| where is the blind spot located on the eye? | where the optic nerve is |
| in which part of the visual field does the retinal image show high visual resolution and good color discrimination? | in the center of the visual field, which is generated by a high cone density. |
| why don't we see blind spots in our visual field? | because our brain fills in the gap, and the visual field from each eye overlaps, eliminating the blind spot |
| this disorder happens where there is elevated intercranial pressure, resulting in high pressure in the eye as well | glaucoma |
| what changes would you see in a patient's vision if one of their optic nerves is inflammed? | you decrease acuity in the central part of the visual field, because inflammation of optic nerve interferes with the transmission of signals from the retina to the visual cortex |
| pituitary adenoma or meningioma can result in what? | lesion of the optic chiasm because the optic tract lies over the pituitary |
| a bitemporal hemianopia can be caused by what? | a lesion of the optic chiasm |
| what happens when there is damage to the right optic nerve? | shining a flashlight to the right eye will dilate both pupils in a paradoxical fashion |
| what happens when there is damage to the right oculomotor nerve? | the right pupil constantly stays dilated |
| what three things occur during the accomodation reflex? | convergence of the two eyes, thickening of the lens, pupillary constriction |
| how do retinal ganglion respond to edges in the visual field? | during of light stimulus and action potential firing pattern increase in the center and decrease nerar the edges |
| what are the two types of ganglion cells and what are they involved with? | M cells are involved in detecting movement in a stimulus, and P cells are more sensitive to shape, details, and color |
| are there M cells in the fovea? | no |
| which retinal cell have center-surround receptive field response to color? | P cells |
| how many layers are in the lateral geniculate nucleus? | six |
| describe the two ventral layers of the lateral geniculate nucleus | they receive input from M cells and project to layer 4Calpha of the primary visual cortex |
| describe the four dorsal layers of the lateral geniculate nucleus | they receive input from P cells and project to layer 4Cbeta of the primary visual cortex |
| info from the contralateral retina goes to which layers of the lateral geniculate nucleus? | 1,4, and 6 |
| info from the ipsilateral retina goes to which layers of the lateral geniculate nucleus? | 2,3, and five, keeping the information from the two retinal visual fields separate. |
| how is the primary visual cortex organized? | retinotopically |
| the upper portions of the optic radiations project to where? | the superior bank of hte calcarine fissure to the primary visual cortex (area 17) |
| where do the inferior optic radiations terminate? | at the lower bank |
| the primary visual cortex is arranged in a series of hypercolumns, and each hypercolumn includes what? | a set of optical dominance columns, a set of orientation columns, a set of blobs (color processing), interblobs |
| inputs from each eye terminate in idfferent alternating bands of cortex, each about one millimeter wide, and they are called... | ocular dominance columns |
| M canglion cell sof the retina pass through the lateral geniculate nucleus, and projects into the layer 4Calpha of the striate cortex. in this layer, the receptive field of the nurons in this pathway are no longer circular, but what shape? | oblong |
| the cells in the 4Calpha project to the neurons of layer 4B. these latter neurons also have simple receptive fields, but often respond to stimuli from both eyes, and the neurons in layer 4B begin the process of integration that is necessary for what? | binocular vison |
| the cells in layer 4B are also selective for what? | direction, but only if the straight line stimulus is moving in a particular direction. |
| vertically oriented aggregates of neurons in layers 2 and 3 of the primary visual cortex that are sensitive to color of vision. | blobs |
| between the blobs are... | interblobs |
| this a pathway for transmitting visual signals | blob channel, which passes through the parvocellular layers of the LGN and then converges on the blobs in layer III. |
| the blobs contain only what? | color sensitive neurons in the striate cortex and are thus probably used to analyze the colors of objects |
| this pathway projects to parieto-occipital association cortex. and answer the question "where?" y analyzing motion and spatial relationships between objects as well as between the body and visual stimuli | dorsal pathways |
| these pathways project to occipitotemporal association cortex. they answer the question "what?" by analyzing form, with specific regions identifying colors, faces, letters, and other visual stimuli | ventral pathways |
| the input into the primary cortex is through these three parallel channels | M cell sto cells in layer 4 of hte cortex, P cells to interblobs layers 2,3 of primary visual cortex, P cells to blobs in layers 2,3, of the primary visual cortex. |
| M cells to cells in layer 4 of the primary cortex detects what? | orientation and motion |
| P cells to interblobs layers 2,3 of primary visual cortex detect what? | shape |
| P cells to blobs in layers 2,3 of the primary visual cortex detect what? | color |
| which pathways in the visual cortex project to the parieto-occipital association cortex and what do they tell you? | the dorsal pathways, and they answer the question "where" |
| these pathways in the primary visual cortex project to the occipitotemporal association cortex and answer the question "what" BY analyzing form, with specific regions identifying colors, faces, letters, and other visual stimuli | ventral pathways |
Created by:
aferdo01
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