Spike-frequency adaptation as a mechanism for dynamic coding in V1

We investigate the representation of visual stimuli and the short-term dyna mics of activity within primary visual cortex in a 'free-viewing' scenario with 'saccading eye movements' modeled as a series of visual stimuli that a re flashed onto the retina for the duration of a fixation period (200-300 m s). We assume that the entire activity pattern from the beginning of fixati on until time t constitutes the neural code. Given a noisy (Poissonian) rep resentation it follows that the signal-to-noise ratio increases with time, because more spikes become available for representation. Here, we show that for archiving an optimal stimulus representation in any increasing time-wi ndow beginning with stimulus onset, the processing strategy of the network should be dynamic in the sense that an initially high recurrent cortical co mpetition between orientation selective cells attenuates with time, i.e. me diated by the instrinsic property of spike-frequency adaptation of pyramida l cells. (C) 2001 Elsevier Science B.V. All rights reserved.