Ischemic lesions to the inferior frontal cortex slow perceptual switching.

In bistable perception, conscious experience alternates between two interpretations of an ambiguous stimulus. Functional imaging shows the activation of the inferior frontal cortex (IFC) during such reversals. However, it has remained unclear whether IFC involvement reflects post-perceptual processes such as attention or motor behavior, or contributes to perceptual updating itself. We examined bistable perception in patients with chronic ischemic stroke lesions. Patients with right middle cerebral artery (rMCA) lesions affecting the IFC (n = 8) exhibited fewer spontaneous perceptual changes than those with rMCA lesions sparing the IFC (n = 13), after controlling for age, sex, stroke burden, and non-perceptual task performance. Group differences were observed in a small sample with heterogeneity in lesion characteristics, including lesion volume and severity, which limit definitive causal inference. These preliminary results indicate that IFC damage slows updating of conscious experience in response to ambiguous sensory input, supporting a contributory role of the prefrontal cortex in shaping conscious perception.