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NJIT Mathematical Biology Seminar

Tuesday, September 26, 2006, 4:00pm
Cullimore Hall 611
New Jersey Institute of Technology

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Correlation between neural spike trains increases with firing rate

Jaime de la Rocha

Center for Neural Science
New York University

Populations of neurons in the retina, olfactory system, visual and somatosensory thalamus, and several cortical regions show temporal correlation among their spike trains. Correlated firing has been linked to stimulus encoding, attention, stimulus discrimination, and motor behavior. Nevertheless, the mechanisms underlying the genesis of correlated spiking are poorly understood and it is not clear, for example, whether correlations between the discharges of two unconnected neurons simply reflect the correlation between their afferent currents or whether they depend on other factors (e.g. excitability of the cells). We show that, when input correlations remain fixed, spike output correlation from unconnected pairs of in vitro cortical neurons increases with their discharge rate. We develop a simple statistical theory which shows that this overlooked, yet universal, relationship follows from the threshold nonlinearity intrinsic to all neurons and other physical systems. A functional consequence of this relation is that, if the firing rate of a population of neurons is tuned to a certain stimulus feature, the population correlation inherits the same tuning. We demonstrate that rate and correlation co-tuning can cooperate to dramatically enhance the information transfer across a two layer network of neurons. This relation between rate and correlation in neural activity links two fundamental features of a neural code.