Our cerebral cortex is responsible for our high-level sensory processing, including what decisions we make and how we enact them. So far, our understanding of the cortex is shaped by its distinct parts that are responsible for different functions and senses, such as the auditory cortex being responsible for hearing and the visual cortex looking after what we see. Numerous different cell types respond to various stimuli in an enormous amount of activity within the cortices, yet the top layer of cells are conversely inactive, seemingly unresponsive. A persistent theory has been that these ‘quiet’ neurons are extremely selective and respond only to specific complicated set of stimuli. A number of studies have searched for a perfect combination to activate them, only to find the cells remain unresponsive in all cases. However, a new paper from the Bruno Lab has found that regardless of the type of stimuli, it is in fact unexpected or surprising events that drives these cells.
Research team Dr Rebecca Rabinovich, Dr Daniel Kato and Professor Randy Bruno focused on investigating the ‘quiet’ cells of the somatosensory cortex, primarily associated with touch, by conducting a series of object detection tasks with mice. They observed that mouse neurons remained unresponsive during repeated exposure to stimuli without reward, and became more responsive when they were rewarded. However, crucially, they found that the responses were stronger when there were unexpected deviations in the timings of the trials.