Evidence accumulation relates to perceptual consciousness and monitoring

Conscious perception and the ability to reflect on one's own perceptual experiences both rely on a common neural mechanism of evidence accumulation in the posterior parietal cortex. Recordings from a single neuron in a human participant, combined with electroencephalography in healthy volunteers, showed that detected tactile stimuli triggered neuronal activity resembling the gradual buildup of evidence seen during decision-making. A computational model reproduced the behavioral and neural data, treating a stimulus as detected when accumulated evidence reaches a threshold, and confidence as the distance between the maximal evidence and that threshold. The findings suggest that gradual changes in neuronal dynamics during evidence accumulation underlie both perceptual consciousness and perceptual monitoring.

Study at a glance

Abstract

A fundamental scientific question concerns the neural basis of perceptual consciousness and perceptual monitoring resulting from the processing of sensory events. Although recent studies identified neurons reflecting stimulus visibility, their functional role remains unknown. Here, we show that perceptual consciousness and monitoring involve evidence accumulation. We recorded single-neuron activity in a participant with a microelectrode in the posterior parietal cortex, while they detected vibrotactile stimuli around detection threshold and provided confidence estimates. We find that detected stimuli elicited neuronal responses resembling evidence accumulation during decision-making, irrespective of motor confounds or task demands. We generalize these findings in healthy volunteers using electroencephalography. Behavioral and neural responses are reproduced with a computational model considering a stimulus as detected if accumulated evidence reaches a bound, and confidence as the distance between maximal evidence and that bound. We conclude that gradual changes in neuronal dynamics during evidence accumulation relates to perceptual consciousness and perceptual monitoring in humans. Humans consciously experience their surrounding environment and can reflect upon it. Here, the authors use single-neuron recordings, electroencephalographic recordings, and computational methods to show that both conscious experience and self-reflection are related to a common mechanism of evidence accumulation in the posterior parietal cortex.