Christian Piepenbrock, Klaus Obermayer
Lateral competition within a layer of neurons sharpens and localizes the response to an input stimulus. Here, we investigate a model for the ac(cid:173) tivity dependent development of ocular dominance maps which allows to vary the degree of lateral competition. For weak competition, it re(cid:173) sembles a correlation-based learning model and for strong competition, it becomes a self-organizing map. Thus, in the regime of weak compe(cid:173) tition the receptive fields are shaped by the second order statistics of the input patterns, whereas in the regime of strong competition, the higher moments and "features" of the individual patterns become important. When correlated localized stimuli from two eyes drive the cortical de(cid:173) velopment we find (i) that a topographic map and binocular, localized receptive fields emerge when the degree of competition exceeds a critical value and (ii) that receptive fields exhibit eye dominance beyond a sec(cid:173) ond critical value. For anti-correlated activity between the eyes, the sec(cid:173) ond order statistics drive the system to develop ocular dominance even for weak competition, but no topography emerges. Topography is estab(cid:173) lished only beyond a critical degree of competition.