Preprints are manuscripts made publicly available before they have been submitted for formal peer review and publication. They might contain new research findings or data. Preprints can be a draft or final version of an author's research but must not have been accepted for publication at the time of submission.
posted on 15.02.2006by P.C. Bressloff, N.W. Bressloff, J.D. Cowan
Orientation tuning in a ring of pulse-coupled integrate-and-fire (IF) neurons is analyzed
in terms of spontaneous pattern formation. It is shown how the ring bifurcates from a synchronous
state to a non-phase-locked state whose spike trains are characterized by clustered
but irregular fluctuations of the inter-spike intervals (ISIs). The separation of these clusters
in phase space results in a localized peak of activity as measured by the time-averaged firing
rate of the neurons. This generates a sharp orientation tuning curve that can lock to
a slowly rotating, weakly tuned external stimulus. Under certain conditions the peak can
slowly rotate even to a fixed external stimulus. The ring also exhibits hysteresis due to the subcritical nature of the bifurcation to sharp orientation tuning. Such behavior is shown
to be consistent with a corresponding analog version of the IF model in the limit of slow
synpatic interactions. For fast synapses, the deterministic fluctuations of the ISIs associated
with the tuning curve can support a coefficient of variation (CV) of order unity.
This is a pre-print. The definitive version: BRESSLOFF, P.C., BRESSLOFF, N.W. and COWAN, J.D., 2000. Dynamical mechanism for sharp orientation tuning in an integrate-and-fire model of a cortical hypercolumn. Neural Computation, 12(11), pp.2473-2511.