Correlations enhance the behavioral readout of neural population activity in association cortex

Correlations in neural activity in association cortex can benefit behavioral performance in perceptual tasks, even when decreasing sensory information, by facilitating the propagation and the readout of information carried by population activity. Noise correlations (that is, trial-to-trial covariations in neural activity for a given stimulus) limit the stimulus information encoded by neural populations, leading to the widely held prediction that they impair perceptual discrimination behaviors. However, this prediction neglects the effects of correlations on information readout. We studied how correlations affect both encoding and readout of sensory information. We analyzed calcium imaging data from mouse posterior parietal cortex during two perceptual discrimination tasks. Correlations reduced the encoded stimulus information, but, seemingly paradoxically, were higher when mice made correct rather than incorrect choices. Single-trial behavioral choices depended not only on the stimulus information encoded by the whole population, but unexpectedly also on the consistency of information across neurons and time. Because correlations increased information consistency, they enhanced the conversion of sensory information into behavioral choices, overcoming their detrimental information-limiting effects. Thus, correlations in association cortex can benefit task performance even if they decrease sensory information.

Automated summary

Correlations in neural activity in association cortex can benefit behavioral performance in perceptual tasks, even when decreasing sensory information. Correlations reduce the encoded stimulus information, but paradoxically increase when correct choices are made. Single-trial decisions not only rely on the stimulus information encoded by the whole population, but also on the consistency of information across neurons and time.