neural model of horizontal and interlaminar cortical development and adult perceptual grouping

[Stephen Grossberg]

The following article can be accessed at

http://www.cns.bu.edu/Profiles/Grossberg

Paper copies can also be gotten by writing Mr. Robin Amos, Department of
Cognitive and Neural Systems, Boston University, 677 Beacon Street, Boston,
MA 02215 or amos at cns.bu.ed

Grossberg S. and Williamson J. R. (2000). A neural model of how horizontal
and interlaminar connections of visual cortex develop into adult circuits
that carry out perceptual grouping and learning. Cerebral cortex, in press.
The paper is available in PDF format GroWil00.pdf, or in Gzipped postscript
format GroWil00.ps.gz.

ABSTRACT: A neural model  suggests  how  horizontal  and  interlaminar
connections  in  visual  cortical areas  V1  and  V2  develop  within a
laminar  cortical  architecture and give rise to adult visual percepts. The
model suggests how mechanisms  that  control  cortical
development  in  the  infant lead to properties of  adult cortical anatomy,
neurophysiology, and visual perception.  The  model clarifies  how
excitatory  and inhibitory connections  can develop stably by maintaining a
balance between excitation and inhibition. The growth of long-range
excitatory horizontal connections between layer 2/3 pyramidal cells is
balanced against that of short-range disynaptic interneuronal connections.
The growth of excitatory on-center connections from layer 6-to-4 is
balanced against that of inhibitory interneuronal off-surround connections.
These  balanced  connections interact via intracortical and intercortical
feedback to realize properties of perceptual grouping, attention,  and
perceptual learning in  the  adult, and help to explain the observed
variability in the number and temporal distribution of spikes emitted by
cortical neurons. The  model replicates  cortical  point  spread functions
and psychophysical  data  on  the strength of real and illusory contours.
The on-center off-surround  layer 6-to-4 circuit enables  top-down
attentional signals  from  area  V2  to  modulate, or  attentionally prime,
layer 4 cells in area V1 without fully activating them. This modulatory
circuit also enables adult perceptual learning within
cortical area V1 and V2 to proceed in a stable way.