Neuro Flashcards
splitting of optic chiasm would result in what?
bitemporal hemianopsia and loss of stereo for uncrossed disparity along the midline
Some people who have ocular albinism have….
Complete decussation which could result in strabismus and no stereopsis
macular sparing means…
part of the field goes past the macula
what part of the brain detects disparities larger than +/-2 degrees around the vertical midline?
Corpus collosum
Where is the central visual field represented?
posterior LGN
Where is the periphery visual field represented?
Anterior LGn
Where is the superior visual field represented?
lateral-inferior LGN
Where is the inferior visual field represented?
medial-superior LGN
Where are the parvocellular layers of LGN? What percent of retinal input does this make up?
Dorsal, layers 3-6
80% retinal input
Where are the magnocellular layers of LGN? What percent of retinal input does this make up?
Ventral, layers 1-2
7-9%
Where are the koniocellular layers of LGN?
Interstitial K1-K6
What layers of the LGN have ipsilateral input?
Layers 2,3,5
What layers of the LGN have contralateral input?
1,4,6
What categories of Hubel and Wiesel are monocular?
Type 1 and 7
What column has the highest proportion of monocular neurons?
4C
What is another name with position coding?
positional disparity (in eye)
What is meant by phase coding?
No positional disparity but ON/OFF receptive fields are different
What percent of V1 neurons are binocular?
over 50% but not in IVCa or IVCb
What percent of neurons in V1 foveal and parafoveal are binocular?
97%
two reciprocal neurons
Near (NE)
Far( FA)
disparity tuned neurons
Tuned zero (To)
Tuned Inhibitory (TI)
Tuned Near (TN)
Tuned Far (TF)
What are flat neurons?
Binocular neurons that are not disparity selective
Percentages of foveal and parafoveal binocular neurons found
Disparity tuned (64%)
Flat (50%)
Reciprocal (16%)
Do near neurons show higher response in crossed or uncrossed disparities?
crosses disparity
Do far neurons show higher response in crossed or uncrossed disparities?
uncrossed disparity
What are far and near reciprocal neurons involved with?
vergence initiation
What kind of stimuli does To (Tuned zero) and TI (tuned inhibitory) prefer?
Prefer stimulus on the horopter. They are inverse of each other.
What do To (Tuned zero) and TI (tuned inhibitory) neurons have roles in?
Fixation maintenance and stereoacuity
What kind of stimuli does TN (Tuned near) and TF (tuned far) prefer?
Prefer stimuli near the horopter but not on the horopter.
What does TN (Tuned near) and TF (tuned far) play a role in?
Vergence initiation
Fixation maintenance
What percent of V2 neurons respond to disparity?
70%
Where would you find cytochrome oxidase stripes?
In the V2 area.
What are the thick stripes in the v2 shown to be selective for? What kind of input is it?
Largely magnocellular input.
Disparity and motion
Low spatial frequency, high temporal frequency
What are the pale stripes in the v2 shown to be selective for? What kind of input is it?
Parvocellular input
Fine stereopsis, good for detecting high spatial frequency, low temporal frequency
What kind of input is the thin stripes in the V2?
Parvocellular input via blobs
In v3, how many neurons respond to disparity?
50%
What does v3 respond to?
Static disparity
Where is v5 found? What is it specific for?
Middle temporal cortex
Specific for motion and binocular disparity.
What is specific for optic flow neurons and gives information about self-motion?
MST (Middle superior temporal area) (V5)
If a person has difficulty grasping with their hand, where could the lesion be?
PPC (Posterior parietal cortex)
