Fluctuations in neuron pairs and populations - modelling and mechanisms

Eric Shea-Brown

It has been proposed by Zohary and collaborators that a primary
source of fluctuations in population-averaged firing rates is
spike-to-spike correlation amongst the constituent neurons, and
these and future authors have highlighted a variety of
implications for the neural code. However, a general mechanistic
understanding is still lacking of how these correlations develop
in neural populations, and, critically, how their strength depends
on the population operating range (that is, the rate and
regularity of its inputs or its spiking).  Our new results toward
such an understanding include (i) the surprising finding that
these correlations increase dramatically with firing rate over
ranges of up to approximately 20-30 Hz. in spiking neuron models
(independently of of the accompanying regularity -- or lack
thereof -- in single-cell spiking), (ii) an intuitive explanation
of this fact based on the linearity of input-output relationships
of individual cells, (iii) and an analysis of implications for
encoding and transmission of static stimuli via population firing
rates.  This is joint work with Jaime de la Rocha, Brent Doiron,
and Kresimir Josic.