Hierarchical Reconfiguration of Neurocognitive Task Set Representations Mediates Cognitive Flexibility.

Cognitive control organizes abstract contexts, stimuli, and actions into hierarchically structured representations. This organization supports flexible behavior but requires updating at multiple levels of the hierarchy, a process reflected in task switch costs. However, it remains unclear how updating differs across levels of abstraction and how these differences relate to behavior and neural representations. Here, we investigated the behavioral and neural sources of switch costs using fMRI and behavioral data from healthy adult participants (male and female). We employed a hierarchical control task that dissociates abstract context reconfiguration from more concrete task-set reconfiguration of stimulus-response mappings. We predicted that task sets, which incorporate sensory-motor mappings, would be more strongly influenced by feedforward inputs than higher-level contextual goals, which are more abstracted from immediate perceptual and motor demands. As predicted, subordinate rule switches were faster and were more strongly influenced by task-irrelevant perceptual changes, whereas context switches were slower and relatively insensitive to such interference. To characterize the neural basis of these effects, we quantified trial-to-trial reconfiguration of multivoxel activity patterns. Across the brain, larger pattern shifts predicted larger RT switch costs, linking representational reorganization to behavioral performance. Importantly, representational reconfiguration differed across hierarchical levels and anatomical systems. Subordinate rule updating was modulated by task-irrelevant perceptual features and expressed in distributed perceptual and motor networks, whereas context reconfiguration engaged the mid-lateral frontal cortex and was comparatively insulated from interference. Our results reveal how the hierarchical structure of neural representations supports flexible updating with interference-shielded contextual representations subserving behavioral control.