Figure 10.

ODM and OSM formation during Phase 2. (A) The ODM appears to have large more contiguous patches of eye selectivity compared to the output after Phase 1. (B) This maturity in ODM formation is caused by more stability in the divergence between the mean and standard deviation calculations in the semilog plots shown here. This divergence is very clear unlike in Figure 7. The mean and standard deviation also seem to stabilize in the later parts of Phase 2. (C) The absolute magnitude of the orientation gradients at each E neuron shows singularities and fractures. Here white indicates high gradient values while black indicates no gradient at all. The gradients image show several fractures in the data. The average fraction of the total synaptic drive at each E neuron selective to a given eye was also calculated. For example, for the “left” E neurons, (∑_i w^left − ∑_i w^right)/(∑_i w^left + ∑_i w^right), was ~71%. Similarly, the fraction was ~70% for the “right” E neurons at the end of Phase 2. (D) Orientation selectivity shows brighter colors that indicate high selectivity with those E neurons in layer 4 respond to a very narrow range of orientations and vice versa. The color scale shows the magnitudes of responses in a relative fashion. For example, neurons in the neighborhood of neuron at (85, 80) show strong selectivity (score of 270) to only 30° but not to other orientations while a neuron at (60, 60) shows a weak selectivity (score of 3) to all orientations including its preferred orientation of 60°. (E) The smoothed orientation preference map shows iso-orientation domains and three weakly formed pinwheels marked by the three black circles. We call these weakly formed pin wheels since they are not corroborated by singularities in the orientation gradient maps. This is because the smoothing operation on the Cartesian images removes the spurious edges created by noisy neuron responses while also removing any trace of the singularities as well. However, close inspection shows that there are three locations marked with black circles where the orientation preferences rotate continuously through ±180° along circular paths. We refer to these patterns as a pinwheel-like pattern. It should be noted that there are no clear appearance of point discontinuities in the orientation gradient maps to corroborate the pin-wheel centers within these pinwheel-like-patterns that clearly appear in animal data.