Striate Cortex Flashcards
Thickness of grey matter
4mm
Cortical surface area
2200 cm2
How many neurons in cortex?
10^10
How many synapses in cortex
10^15
Retinotopically organzied
Neighboring parts of the visual field are processed by neighboring cells in the cortex
Cortical magnification factor
Large proportion of striate cortical neurons devoted to analysis of foveal vision
Extrastriate
All visually resonsive areas that do not recevie information from LGN
What do neurons in the striate cortex respond best to?
Lines, edges, or bars
Simple cells respond best to
Elongated stimuli
What shape are receptive fields of simple cells
Rectangular
2 requirements for excitation of simple cells
Specific orientation
Proper positioning
Hierarchical processing
Building of more complex RF configurations from simpler RF configurations
Where is the stimulus positioned for complex cells?
Anywhere withing the receptive field
T/F Complex cells respond to stationary bars
False, motion sensitive
Directional sensitivity
Complex cells respond best to bar moving in a specific direction
What is the importance of microsaccades?
Keep the retinal image from fading
How can you increase the response of the cell?
By increasing the length of the stimulus to a certain point
Hypercomplex cells
Show an increase in response with an increase in stimulus length until the stimulus exceed the critical limit, when the response begins to decrease
Stereopsis
Innate binocular sensation of depth
What 2 things does binoculalrity allow for?
Stereopsis and a larger field of vision
Where are the first binocular neurons located?
Outside of layer 4 in the striate cortex
Ocular dominance columns
Neurons driven predominantely be each eye are grouped together runnng perpendicular to the cortical surface
Orientation columns
Neurons most responsive to a specific orentiation grouped in functional columns
Hypercolumn
Most basic unit of the cortex comprising of a full complement of ocular dominance columns and orientation columns that respresents a specific point in the visual field
What 3 things do hypercolumns extract from visual information?
Depth, orientation, and color
What kind of pathway is the ventral stream?
What pathway, gives detail, color, and form information
What type of pathway is the dorsal stream?
Where pathway, gives information on where the object is located
Blobs
Surplus of neurons with color opponent receptive fields
Thin stripes are P or M?
Parvo
Pale stripes are P or M
Parvo
Thick stripes are P or M?
magno
Cortically blind
Complete damage to V1
Blindsight
A phenomenon in which a patient who is cortically blind from a lesion in area V1, can seemingly perceive light
What type of experiment proves blindsight?
Two-alternative forced choice
What is a theory that explains blindsight?
Some optic nerve axons bypass the LGN and project to other areas
Where must information go in order to be conscious visual perception?
LGN and V1
