NETWORK-GUIDED IDENTIFICATION OF CORTICAL TARGETS FOR MODULATING OBJECT-LOCATION MEMORY

Object-location memory (OLM), a fundamental component of spatial memory, is essential for everyday functioning yet declines with aging and neurodegenerative disorders. OLM critically depends on medial temporal lobe (MTL) structures but cannot be directly targeted by conventional non-invasive brain stimulation (NIBS) like transcranial direct current stimulation (tDCS). This study aimed to identify stimulation-accessible cortical nodes functionally coupled with hippocampal memory circuits during OLM learning, providing a network-guided framework for neuromodulation via NIBS.
Nineteen healthy adults performed a feedback-based OLM task during fMRI. A closely matched non-associative task controlled perceptual and motor demands. Task-dependent functional connectivity was assessed using generalized psychophysiological interaction (gPPI) analyses, combining ROI-to-ROI and seed-to-voxel approaches. Connectivity-behavior relationships were examined across and within learning stages.
OLM learning selectively increased functional coupling between hippocampus/parahippocampal cortex and ventral visual-occipito-temporal regions, including inferior and middle temporo-occipital gyri, fusiform gyrus, and lateral occipital cortex. Stronger cortico-MTL connectivity predicted higher learning accuracy across individuals, particularly during early learning stages. Importantly, temporo-occipital regions. anatomically accessible to NIBS, showed robust and behaviorally relevant coupling with hippocampal structures.
These findings identify a distributed cortico-hippocampal network supporting OLM and highlight temporo-occipital cortex as a promising stimulation target for modulating hippocampal memory function. By linking task-evoked connectivity with learning success, this work provides a mechanistic and empirically grounded basis for network-guided neuromodulation strategies aimed at enhancing spatial memory.