Exam 4 -- Visual Cortex Flashcards
The koniocellular layers in the LGN synapse with which layers of V1?
Layers 2 and 3
The parvocellular layers in the LGN synapse with which layer of V1?
4C-beta (also 4A)
The magnocellular layers in the LGN synapse with which layer of V1?
4C-alpha
Which cells in the visual cortex have axons that usually do not leave the cortex?
Stellate
Which cells in the visual cortex have axons that commonly leave the cortex?
Pyramidal
Projections to the extrastriate area originate in particular from which layers of V1?
Layers 2/3
In which layer of V1 does figure-ground and binocularity begin?
Layer 2
Projections to the lower visual centers (LGN, pulvinar) original in particular from which layer of V1?
Layer 6
Which layer of V1 sends fibers to the superior colliculus?
Layer 5
What percent of the retinal area is the fovea, and what percent of the striate cortex is devoted to foveal vision?
0.01% of foveal area; 8% of striate cotex.
Simple cortical cells respond to what kind of stimulus?
Orientation. They can be on-off, or edge detectors.
Complex cortical cells respond to what kind of stimulus?
Unidirectional movement.
True or false: hypercomplex cells are real.
False; they are not real. They were proposed by Hubel and Wiesel, but turned out to be incorrect.
True or false: simple and complex cortical cells are sensitive to the length of a stimulus (they have end stops).
True.
There is a regular shift in orientation sensitivity as you move along the surface of the cortex. A complete circular set of orientation edge detectors is called what?
Hypercolumn
Ocular dominance columns respresent neurons that get the majority of their input from _________ (one/both) eye(s).
One.
Where are the disparity cells of our visual system located?
V2 for complex cells, V3 for local motion.
There are two categories of coarse stereo cells: far and near. Which of these is excited if an object is beyond the point of fixation and inhibited if the object is closer than the point of fixation?
Far coarse cells. Near coarse cells are the opposite (excited to nearer than fixation, inhibited to further than fixation).
___________ stereo cells make up 30% of disparity detectors.
Coarse
________ stereo cells make up 50% of disparity detectors
Tuned excitatory (fine)
________ stereo cells make up 20% of disparity detectors
Tuned inhibitory (fine)
Fine stereo cells are sensitive to specific disparities, up to what point?
Up to 1 degree.
Moderate and higher uncorrected astigmatism during childhood causes what kind of amblyopia? How would you treat it?
Meridional amblyopia; treat with full-time wear of full correction of all cylinder measured on wet retinoscopy.
How much anisometropia is typically required for symptomatic aniseikonia?
2.00 D or more
What percent in size difference is needed before aniseikonia causes symptoms? To what percent is the Aniseikonia Inspector Software accurate?
2% size difference needed for symptoms; Aniseikonia Inspector accurate to 0.1%
Base out makes the binocular image look _______ (smaller/larger).
Smaller
Base in makes the binocular image look _______ (smaller/larger).
Larger
