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- U. Bauer, P. Adorjan,
M. Scholz, J. B. Levitt, J. S. Lund, and K. Obermayer. On the Anatomical
Basis of Field Size, Contrast Sensitivity, and Orientation Selectivity in
Macaque Striate Cortex: a Model Study.
.
In W. Gerstner, A. Germond, M. Hasler, and J. Nicoud, editors, Artificial
Neural Networks - ICANN 97, pages 213-218. Springer-Verlag, 1997.
(FTP Gzipped PostScript, 6 pages, 61 kb)
Neurons in layer 4C in macaque striate cortex show a differential
change in receptive field size and achromatic contrast sensitivity with
depth, and exhibit orientation selective responses in the upper 4Calpha
sublayer. Using a computational model we first demonstrate that the observed
change in receptive field size and contrast sensitivity can arise from a
differential convergence of afferents from the P and M sub divisions of the
lateral geniculate nucleus on to layer 4C spiny stellate cells - if one
postulates that the two anatomically identified M1 and M2 subpopulations of
the M afferents differentially project to different depth in the 4Calpha
subdivision. Number ratios and response properties of both M subpopulations
are predicted and may now be tested experimentally. We then show that
realistic orientation selective responses in upper 4Calpha can emerge in
tracortically as a result of local lateral interactions, which are
anisotropic, between spiny stellate cells and inhibitory interneurons. The
model assumes that orientation bias and tuning are generated by the same
cortical circuits and predicts a receptive field dynamics with an initial non
orientation specific response.
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