Pc. Bressloff et al., Dynamical mechanism for sharp orientation tuning in an integrate-and-fire model of a cortical hypercolumn, NEURAL COMP, 12(11), 2000, pp. 2473-2511
Citations number
49
Categorie Soggetti
Neurosciences & Behavoir","AI Robotics and Automatic Control
Orientation tuning in a ring of pulse-coupled integrate-and-fire (IF) neuro
ns is analyzed in terms of spontaneous pattern formation. It is shown how t
he ring bifurcates from a synchronous state to a non-phase-locked state who
se spike trains are characterized by clustered but irregular fluctuations o
f the interspike intervals (ISIs). The separation of these clusters in phas
e space results in a localized peak of activity as measured by the time-ave
raged 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 extern
al stimulus. The ring also exhibits hysteresis due to the subcritical natur
e 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 l
imit of slow synaptic interactions. For fast synapses, the deterministic fl
uctuations of the ISIs associated with the tuning curve can support a coeff
icient of variation of order unity.