Flavor Pleasantness Enhances Cross-Network Integration Between Olfactory and Gustatory Regions: A Functional and Effective Connectivity Study

Background Flavor perception involves complex integration of olfactory, gustatory, and trigeminal inputs, yet the neural dynamics underlying the hedonic evaluation of flavor remain insufficiently understood. This study investigates how subjective flavor pleasantness modulates functional and effective connectivity within key olfactory and gustatory brain networks. Methods Nineteen participants underwent fMRI scanning while performing a taste evaluation task involving pleasant, neutral, and unpleasant stimuli. Functional connectivity was analyzed using seed-based and ROI-to-ROI approaches via the CONN toolbox, while effective connectivity was assessed using Dynamic Causal Modeling (DCM) with Bayesian model selection. Core regions included the insula, orbitofrontal cortex (OFC), dorsolateral prefrontal cortex (DLPFC), ventrolateral prefrontal cortex (VLPFC), hippocampus, and amygdala. Results Seed-based and ROI-to-ROI analyses revealed significant modulation of connectivity by flavor pleasantness, particularly among the insula, VLPFC, hippocampus, and OFC. The strongest bidirectional interactions were observed between the insula and VLPFC, and between the hippocampus and insula. Effective connectivity models incorporating modulatory input to the OFC had the highest model evidence, supporting its role as a target of directed influences from the VLPFC, DLPFC, and hippocampus. Conclusions These findings indicate that flavor pleasantness emerges from coordinated interactions across partially overlapping olfactory and gustatory networks. By combining functional and effective connectivity approaches, this study provides a network-level account of hedonic flavor processing, identifying the insula and OFC as dynamic hubs that integrate sensory input with cognitive and affective information. This framework offers new insight into the neural architecture of flavor evaluation and may inform future research on chemosensory dysfunction and eating-related disorders.