Unveiling Mesoscale Finger-specific Neural Circuits through Near-infrared Stimulation and fMRI Mapping

Motivation: The dexterity of individuated finger movements is fundamental to daily hand use; yet specific brain networks serving each finger remains poorly understood. Goal(s): Our objective is to unravel mesoscale connections associated with finger-specific neural circuits. Approach: In 2 macaque monkeys, single digit locations were functionally mapped in cortical areas 3b via fMRI. Pulsed INS (infrared neural stimulation) targeted to these sites elicited mesoscale BOLD activation at functionally connected sites resulting in brainwide single digit networks. Results: INS-induced BOLD activations revealed the distinct networks associated with each finger. Index finger connected with sensorimotor, multisensory and emotion circuits, supporting flexibility and stability in fine movement. Impact: This research identifies specific brain networks underlying single digit maps in SI, and will be relevant for understanding hand dexterity, neurorehabilitation, and prosthesis development.