Pooling and correlated neural activity

Robert J Rosenbaum

doi:10.3389/fncom.2010.00009

Abstract

Correlations between spike trains can strongly modulate neuronal activity and affect the ability of neurons to encode information. Neurons integrate inputs from thousands of afferents. Similarly, a number of experimental techniques are designed to record pooled cell activity. We review and generalize a number of previous results that show how correlations between cells in a population can be amplified and distorted in signals that reflect their collective activity. The structure of the underlying neuronal response can significantly impact correlations between such pooled signals. Therefore care needs to be taken when interpreting pooled recordings, or modeling networks of cells that receive inputs from large presynaptic populations. We also show that the frequently observed runaway synchrony in feedforward chains is primarily due to the pooling of correlated inputs.

Highlights

Cortical neurons integrate inputs from thousands of afferents
A similar model is used to examine the impact of pooling on the statistics of inputs to cells
The increase in correlation due to pooling was discussed in a simpler setting in (Bedenbaugh www.frontiersin.org and Gerstein, 1997; Super and Roelfsema, 2005; Chen et al, 2006; Stark et al, 2008), and similar ideas were developed for the variance alone in (Salinas and Sejnowski, 2000; Moreno-Bote et al, 2008)

Summary

Introduction

Cortical neurons integrate inputs from thousands of afferents. a variety of experimental techniques record the pooled activity of large populations of cells. It has been observed that weak correlations between cells in two populations can cause much stronger correlations between the pooled activity of the populations (Bedenbaugh and Gerstein, 1997; Chen et al, 2006; Gutnisky and Josic, 2010; Renart et al, 2010). The connectivity in the presynaptic network was irrelevant – it only mattered that the inputs to the downstream neurons reflected the pooled activity of the afferent populations. A similar effect can cause large correlations between recordings of multiunit activity (MUA) or recordings of voltage sensitive dyes (VSD), even when correlations between cells in the recorded populations are small (Bedenbaugh and Gerstein, 1997; Chen et al, 2006; Stark et al, 2008). The effect is the same, but in this case pooling occurs at the level of a recording device rather than a downstream neuron (compare Figures 1A,B)

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