Information encoding in the inferior temporal visual cortex: contributions of the firing rates and the correlations between the firing of neurons

The encoding of information by populations of neurons in the macaque inferior temporal cortex was analyzed using quantitative information-theoretic approaches. It was shown that almost all the information about which of 20 stimuli had been shown in a visual fixation task was present in the number of spikes emitted by each neuron, with stimulus-dependent cross-correlation effects adding for most sets of simultaneously recorded neurons almost no additional information. It was also found that the redundancy between the simultaneously recorded neurons was low, approximately 4% to 10%. Consistent with this, a decoding procedure applied to a population of neurons showed that the information increases approximately linearly with the number of cells in the population.