The role of correlated firing and synchrony in coding information about single and separate objects in cat VI

It has been suggested that correlated activity between groups of neurons indicates that they are responding to the same object. Evidence from visual cortex is controversial. We recorded multiunit activity from two different electrodes in V1 cortex of anaesthetized cats while presenting 0, 1 or 2 objects. We quantified how much information about stimulus configuration is contributed by independent rate modulations, and how much is added by correlated firing. We found that correlated firing increased the information carried by the firing rates of the recording sites. However, the information contributed by correlations was small compared to that of rates.