Abstract
Visual grouping of collinear fragments is thought to rely largely on long-range horizontal connections in layer 2/3 of primary visual cortex (Gilbert et al., 1996) and extrastriate cortex (Von der Heydt et al., 1984). Such interactions have been incorporated into neural models of perceptual grouping (Grossberg and Mingolla, 1985), which have been extended to LAMINART models that incorporate detailed laminar circuitry (Grossberg and Raizada, 2000). These models have explained and predicted a wealth of psychophysical, anatomical, and neurophysiological evidence. They have not, however, incorporated spiking dynamics to address data that depend on how individual spikes and bursts of spikes are influenced, in particular synchronized, by perceptual grouping circuits. The current spiking laminar cortical model includes identified cells in, among others, layers 6, 4 and 2/3 of both V1 and V2. Model cells are implemented as two compartments, where one compartment is a dendrite and the other one is a soma governed by Hodgkin-Huxley equations. Cells are connected via AMPA and GABA synapses and are constrained by slow conduction speeds for long-range horizontal connections (Bullier, 2001). The model is simulated on a variety of diagnostic experimental conditions. Numerical results show that the model, when constrained by realistic spiking dynamics, can account for electrophysiological data about spikes, while also displaying essential psychophysical properties of perceptual grouping.
Supported in part by the NSF (SBE-0354378).