Cortical activation in precision grip and its association with manual dexterity: a foundational fNIRS study.

Fine motor tasks that involve precision grip depend on both motor control and cognitive processes. However, the neural mechanisms underlying individual differences in manual dexterity remain incompletely understood, particularly under ecologically valid task conditions. The present study aimed to establish a controlled functional near-infrared spectroscopy (fNIRS) paradigm capable of isolating cortical activation specifically elicited by precision grip, and to examine whether such activation is associated with individual differences in manual dexterity. Manual dexterity was assessed using the Purdue Pegboard test (PPT). Cortical activity was measured using 44-channel fNIRS while 40 young adult participants performed temporally controlled precision grip tasks derived from the PPT with either their right or left hand. Precision grip tasks elicited significant increases in oxyhemoglobin signal in bilateral prefrontal and sensorimotor regions compared with a control task. Furthermore, higher PPT assembly scores were associated with greater task-related activation in the lateral prefrontal cortex during right-hand precision grip task. In applied terms, greater task-evoked activation should be interpreted as increased cortical recruitment required to meet precision demands, rather than as inherently superior performance. Taken together, these preliminary findings provide a foundational reference for understanding precision grip–related cortical recruitment and its association with individual differences in manual dexterity, and demonstrate the feasibility of using fNIRS to study cognitive–motor integration under realistic task conditions.