Increased Perceptual Reliability Reduces Membrane Potential Variability in Cortical Neurons.

Uncertainty is omnipresent. While humans and other animals take uncertainty into account during decision making, it remains unclear how it is represented in cortex. Recent theoretical work on uncertainty computation in cortical neurons predicts a stimulus-triggered decrease of the within-trial membrane potential variability. Yet, testing this prediction in experimental data is uniquely challenging as it would require a large number of intracellular recordings in vivo. We thus leverage simulation-based inference to gain insights about the membrane potential statistics underlying single unit spiking activity. This allows us to investigate the effect of stimulus reliability on membrane potential variability in posterior parietal cortex neurons while male mice performed a multisensory change detection task. The inferred membrane potential statistics show that neurons decrease their membrane potential variability in response to task-relevant stimuli. In particular, more perceptually reliable stimuli lead to larger decreases in membrane potential variability than less reliable ones, in line with theoretical predictions. These findings suggest that cortical neurons track uncertainty, providing Bayesian benefits for downstream computations.