Distractor suppression in primary visual cortex

Selective attention is fundamental for effective interaction with our surroundings. A primary mechanism behind this capability is the automatic suppression of the numerous distracting stimuli that compete for our attention. This suppression allows us to focus on essential tasks, like driving a car, without being overwhelmed by salient but irrelevant inputs. While the behavioral benefits of distractor suppression are well-established, its neural underpinnings are not yet fully understood. In an fMRI study, we examined where and how sensory responses in the visual brain display signs of distractor suppression after incidental learning of spatial statistical regularities. Participants were exposed to an additional singleton task where, unbeknownst to them, one location more often contained a highly salient distractor. We then analyzed whether visual responses in terms of fMRI BOLD were modulated by this predictability. Our findings indicate that such implicit spatial priors shape sensory processing even at the earliest stages of cortical visual processing in V1, evident as a suppression of stimuli at locations which frequently contained the distracting information. Notably, this suppression occurred when distractor or target stimuli appeared at the high probability distractor location, suggesting that suppression arises before stimulus identification completed. These results highlight a proactive strategy employed by early visual cortex, where potential distractions are suppressed preemptively, possibly even before the onset of the stimulus display. In sum, our study underscores how the brain leverages prior knowledge, for example from statistical learning, to optimize sensory processing and attention allocation.