Sensory representation of a cued tactile stimulus in the posterior parietal cortex of the mouse

The cognitive process of attention allows for the selective processing of salient stimuli over others, when we are constantly challenged with multiple stimuli that engage our senses. The fronto-parietal attention circuit in the mammalian neocortex, of which the posterior parietal cortex (PPC) is part of, plays a role in the selection of pertinent stimuli. However, how a sequence of sensory information, where one stimulus is cued by another, is represented in PPC during attention is poorly understood. Here, using 2-photon imaging in awake behaving mice, we show that neurons in layer 2/3 of the mouse PPC can reliably represent texture touch events, in addition to auditory cues that predict the incoming tactile stimulus. Notably, omission of the cued texture touch elicited a large response in a subset of neurons that were largely non-responsive to or inhibited by the tactile stimuli. A higher proportion of PPC neurons were able to detect the stimulus omission, as compared to discriminating stimulus features (texture graininess). Our results suggest that the layer 2/3 network in PPC participates in stimulus encoding and could potentially further function as a reporter of mismatch signals under conditions of stimulus omission. Significance statement The posterior parietal cortex (PPC) is implicated in a variety of functions, ranging from spatial navigation and attention to multisensory processing and perceptual decision making. Here we show that in addition to discriminating stimulus features, the PPC can signal the omission of a cued stimulus and potentially function as a reporter of stimulus mismatch.