Graded prefrontal-sensory connectivity underlies cross-modal hierarchical control

Does the rostro-caudal architecture of the prefrontal cortex (PFC) generalize to support hierarchical control across sensory modalities? To address this question, we used functional magnetic resonance imaging while participants performed three cue-based tasks integrating auditory and visual modalities, requiring policy abstraction from auditory cues to motor responses, visual features, or visual dimensions. Behaviorally, increasing abstraction and complexity produced robust costs in accuracy and reaction time, underscoring the computational demands of cross-modal control. Univariate analyses revealed complexity-modulated effects within each level of abstraction and a corresponding anterior shift in PFC activation paralleling the hierarchical gradient. Multivoxel pattern analysis further demonstrated a representational shift, where caudal PFC encoded concrete motor responses, whereas rostral PFC represented abstract dimensions. Functional connectivity analyses revealed a complementary dissociation: caudal subregions showed selective, complexity-modulated coupling with primary sensory cortices during lower-level control, whereas rostral PFC exhibited functional independence from direct sensory coupling at the highest level of abstraction. Instead, increasing abstraction was associated with enhanced coupling among higher-order association areas, particularly between the superior temporal and intraparietal regions. Together, these findings extend prior unimodal research by demonstrating that hierarchical control is instantiated along a rostro-caudal gradient that flexibly reconfigures prefrontal-sensory interactions to meet multiple sensory demands. This cross-modal hierarchical architecture enables a transition from direct sensorimotor mappings to abstract regulation, providing a neural basis for adaptive cognition in the complex, multisensory environments of everyday life.