Adaptive coding of stimulus information in human fronto-parietal cortex during visual classification

Abstract

The neural mechanisms of how frontal and parietal brain regions support flexible adaptation of behavior remain poorly understood. Here, we used functional magnetic resonance imaging (fMRI) and model-based representational similarity analysis (RSA) to investigate frontoparietal representations of stimulus information during visual classification under varying task demands. Based on prior research, we predicted that increasing perceptual task difficulty should lead to more categorical coding of stimulus information, and that exemplar-level stimulus coding would be restricted to posterior, sensory brain regions. Counter to our expectations, however, we found frontoparietal regions encoded exemplar-level stimulus information. Interestingly, the anterior intraparietal sulcus (aIPS) encoded stimuli equally well regardless of perceptual difficulty, and these representations were directly related to choice behavior (proportion of guessing). Overall, these findings reveal unexpected exemplar-level stimulus coding in frontoparietal cortex, and highlight the role of aIPS in supporting adaptive behavior.