complex cells receptive fields
Complex cells have receptive fields like simple cells, with one big exception: they abstract for position.
Simple cells are
cortical cells which respond to more complex stimuli and receptor fields than ganglion cells.
Simple cells receptive fields
- Their receptive fields are created from converging LGN neurons with center-surround receptive fields.
- This creates a receptive field shape that is a straight line, and the orientation of the line is crucial.
- This is an example of hierarchical processing
several cells with similar but spatially offset receptive fields converge on a higher order cell to create an altogether new type of receptive field.
While simple cells require a ______;
complex cells require _______.
line or edge at a particular position in the visual field,
are not so finicky about position. The line or edge can be anywhere within the receptive field, and these cells especially like to see lines or edges moving across the field.
Major inputs are a convergence of several simple cells whose positions are slightly offset. The converging simple cells make:
excitatory synapses on the complex cell, and any single simple cell can cause the complex cell to fire
Visual processing at the cortical level is initiated in ____
V1, the primary visual area.
V1 is functionally specialized to ____
- ocular dominance
- color information from specific retinal locations.
The cells in V1 are organized in ___
an array of hypercolumns, each of which corresponds to a point on the retina.
Each column in the hypercolumn responds to
a particular orientation;
adjacent columns manage information from adjacent retinal locations.
Hypercolumns are 1 mm on a side and receives information from about _____.
10,000 LGN axons
Color information, which is separated out from spatial information in the ____, is handled in _____
central regions of the hyercolumns called blobs.
The orientations of lines in the visual field lie in _____.
different rays of pinwheels that radiate from the central blobs.
All cells in a vertical column are sensitive to the same orientation.
Of the many different types of cells in V1, _____ are most important to the perception of color.
blobs and interblobs
blobs and interblobs receive input from:
the parvo cells of the LGN
blobs and interblob function
continue the processing of color information
Sensitive period (or critical period):
period of time when connections can be altered by visual experience.
For humans, the critical period is
the first 2 -3 years
connections of critical period
while genetically determined, are not immutable, at least for a while after birth.
Indicate the conditions under which the effects of abnormal developmental experiences can be reversed.
If the abnormal development is detected and treated within the sensitive period, the effects of abnormal development up until that point can be reversed.
example of conditions under which the effects of abnormal developmental experiences can be reversed.
Infants born with congenital strabismus or cataracts can end up with relatively normal vision, provided these defects are detected and repaired soon after birth.
However, the longer you wait, the greater the visual deficit will be. If not repaired by 2 years of age, there will be substantial permanent visual deficits