Striate Cortex

Question 1

Where does the first stage of cortical processing occur. Where is it located?

Answer 1

within the striate cortex; within the occipital lobe.

Question 2

The striate cortex is dominated by the _____.

Answer 2

fovea

Question 3

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.

Answer 3

edge; bar

Question 4

The receptive field of a simple cell is thought to represent a ______ arrangement of LGN cell receptive fields.

Answer 4

linear

Question 5

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.

Answer 5

direction

Question 6

Nonlinear _____ cells play a larger role in the formation of the receptive fields of complex cells than they do for simple cells.

Answer 6

magno

Question 7

Endstopped cortical neurons/Hypercomplex cell show sensitivity for _____

Answer 7

length

Question 8

What provides the physiological basis for stereopsis

Answer 8

the stimulus distance between each eye

Question 9

Striate cortex is organized according to orientation as well as ____ dominance

Answer 9

ocular

Question 10

Orientation columns do not extend through layer IV; cells in this layer tend to have a _____ organization

Answer 10

concentric

Question 11

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

Answer 11

superior colliculus

Question 12

Parallel processing occurs in concert with ______ processing.

Answer 12

hierarchial

Question 13

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.

Answer 13

4calpha; 4B; thick; 2; middle temporal; dorsal

Question 14

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.

Answer 14

4cbeta; blobs; interblobs; thin; 4; pale; ventral

Question 15

Simple cells have distinct excitatory and inhibitory regions. They follow the ____ property. They have mutual _____

Answer 15

summation; antagonism

Question 16

Our brain is a ____ detector not a luminance detector

Answer 16

contrast

Question 17

Is the GC size dependent?

Answer 17

No; we still see smudge

Question 18

Does contrast reversal cause the effect of the hermann grid?

Answer 18

Yes; We reversed the contrast and still saw smudges and we even added color and the illusion persisted.

Question 19

Does the effect of the grid persist with a similar relationship between the stimulus and the receptive field?

Answer 19

No; We changed the shape and size of the stimuli (wavy lines) and the illusion disappeared. Changing the orientation also made the illusion disappear

Question 20

Does the discharge and the distribution of retinal ganglion cells fit?

Answer 20

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.

Question 21

Does the spatial arrangement of receptive fields fit?

Answer 21

No; unrealistic

Question 22

The herman grind is referring more to ____ cells than ganglion cells

Answer 22

simple

Question 23

Simple cells are specific for _____ and _____

Answer 23

size; orientation

Question 24

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)

Answer 24

simple; 4B; complex

Question 25

Ocular dominance columns are at layer ____ which is special area for simple cells that process info from LGN, and orientation columns are at layer ____. Intermixed within the orientation columns are ____ where color processing occurs.

Answer 25

4; 3; blobs

Question 26

If there is damage to V1 the ____ is fine, they are effectively blind but they can detect location/movement.

Answer 26

retina

Question 27

Type 1 blindsight has no awareness of stimuli; Type ____ has some stimuli awareness

Answer 27

2

Question 28

Complex cells do not exhibit ____. There are no on-off regions in this cell. They are either all on or all off. (spatially invariant).

Answer 28

antagonism

Question 29

Complex cells signals are modulated by:

Answer 29

1. presence/absence of light
2. direction of light
3. orientation of light

Question 30

hypercomplex cells are sensitive to stimulus ______

Answer 30

length

Question 31

T/F Simple cells are more complex than complex cells

Answer 31

true

Question 32

Simple cells are specific for ____, orientation. They have antagonistic RF. They are ____ detectors. They have on/off response.

Answer 32

size; edge.

Question 33

The LGN is composed of 6 layers. Layers 1, and 2 make up the ____ layers. Layers 3, 4, 5, and 6 make up the _____ layers

Answer 33

magnocellular; parvocellular

Question 34

Which layers are ipsilateral? What about contralateral?

Answer 34

2 3 and 5. 1, 4, and 6 are contralateral.

Question 35

Magnocellular pathway has disparity information, orientation, direction and ___ ____

Answer 35

subjective counter