Isolated correlates of somatosensory perception in the mouse posterior cortex

To uncover the neural correlates of stimulus perception, experimenters commonly use tasks in which subjects are repeatedly presented with a weak stimulus and instructed to report, via movement, if they perceived the stimulus. The difference in neural activity between reported stimulus (hit) and unreported stimulus (miss) trials is then seen as potentially perception-related. However, recent studies found that activity related to the report spreads throughout the brain, calling into question to what extent such tasks conflate perception-related activity with report-related activity. To isolate perception-related activity, we developed a paradigm in which the same mice were trained on both a regular go/no-go whisker stimulus detection task and a reversed contingencies version, in which they reported the absence of a whisker stimulus. By comparing no-report trials across the two tasks, we located perception-related activity within a posterior network of cortical regions contralateral to the stimulus. In addition, we found this activity was on average an order of magnitude lower than report-related activity and began after the low-level stimulus response. In summary, our study revealed the mouse cortical areas associated with the perception of a sensory stimulus independently of a perceptual report.