Part of Advances in Neural Information Processing Systems 12 (NIPS 1999)
Péter Adorján, Lars Schwabe, Christian Piepenbrock, Klaus Obermayer
We investigate the short term .dynamics of the recurrent competition and neural activity in the primary visual cortex in terms of information pro(cid:173) cessing and in the context of orientation selectivity. We propose that af(cid:173) ter stimulus onset, the strength of the recurrent excitation decreases due to fast synaptic depression. As a consequence, the network shifts from an initially highly nonlinear to a more linear operating regime. Sharp orientation tuning is established in the first highly competitive phase. In the second and less competitive phase, precise signaling of multiple ori(cid:173) entations and long range modulation, e.g., by intra- and inter-areal con(cid:173) nections becomes possible (surround effects). Thus the network first ex(cid:173) tracts the salient features from the stimulus, and then starts to process the details. We show that this signal processing strategy is optimal if the neurons have limited bandwidth and their objective is to transmit the maximum amount of information in any time interval beginning with the stimulus onset.