Striate Cortex Flashcards
Where does the first stage of cortical processing occur. Where is it located?
within the striate cortex; within the occipital lobe.
The striate cortex is dominated by the _____.
fovea
Simple cells are most sensitive to an ____ or ____ of a specific orientation. The stimulus, if a bar must be of a specific width and must be properly positioned within the cells receptive field.
edge; bar
The receptive field of a simple cell is thought to represent a ______ arrangement of LGN cell receptive fields.
linear
Like simple cells, complex cells respond best to an elongated stimulus of specific orientation. However the stimulus can be positioned anywhere within a complex cell’s receptive field. Complex cells are _____ selective. Unlike simple cells, the receptive fields of complex cells cannot be divided into separate excitatory and inhibitory regions.
direction
Nonlinear _____ cells play a larger role in the formation of the receptive fields of complex cells than they do for simple cells.
magno
Endstopped cortical neurons/Hypercomplex cell show sensitivity for _____
length
What provides the physiological basis for stereopsis
the stimulus distance between each eye
Striate cortex is organized according to orientation as well as ____ dominance
ocular
Orientation columns do not extend through layer IV; cells in this layer tend to have a _____ organization
concentric
Blindsight refers to non conscious vision. This is secondary to a lesion that has destroyed all of striate cortex. But when forced to do so, the pt will see a flash. This is possible because projections may be through ____ ____ and pulvinar. Stimulation of extra striate cortex facilitates non conscious vision
superior colliculus
Parallel processing occurs in concert with ______ processing.
hierarchial
Axons from the magno neurons in the LGN synapse in layer ____of striate cortex which then send their axons to layer ____ which project to the ____ dark stripes in visual area ___. These project to the ____region, giving rise to the ____ processing stream.
4calpha; 4B; thick; 2; middle temporal; dorsal
Axons from the parvo neurons in the LGN project to layer ____ which project to the ____ and ____ which then sends its axons to the ____ stripes in visual area 2 which project to visual area ____.THe inter blob system projects to the ____ stripes in visual area 2. They give rise to the ____ processing.
4cbeta; blobs; interblobs; thin; 4; pale; ventral
Simple cells have distinct excitatory and inhibitory regions. They follow the ____ property. They have mutual _____
summation; antagonism
Our brain is a ____ detector not a luminance detector
contrast
Is the GC size dependent?
No; we still see smudge
Does contrast reversal cause the effect of the hermann grid?
Yes; We reversed the contrast and still saw smudges and we even added color and the illusion persisted.
Does the effect of the grid persist with a similar relationship between the stimulus and the receptive field?
No; We changed the shape and size of the stimuli (wavy lines) and the illusion disappeared. Changing the orientation also made the illusion disappear
Does the discharge and the distribution of retinal ganglion cells fit?
No; stare are red circle and pre adapt you to darkness (black background) As soon as we switch on it should nullify the effect but we still see smudges. They are clearly visible; pre adaptation does not make effect go away.
Does the spatial arrangement of receptive fields fit?
No; unrealistic
The herman grind is referring more to ____ cells than ganglion cells
simple
Simple cells are specific for _____ and _____
size; orientation
Magno cells are almost exclusively _____ cells and go to layer _____. Parvo which are mostly _____ cells go to layers 1, and 2. (Not 2, 3, and 6? ASK)
simple; 4B; complex
