Methods: Out of 8 PD STN-DBS patients, we present here preliminary analysis of a male (62y) PD patient with bilateral STN-DBS (unipolar, 180Hz, 3.5V). The patient was tested after 12h withdrawal of dopamine medications in both an “OFF” and “ON” DBS session separated by 30min. The subject performed a computerised GoNoGo task with 3 alternating Go/ NoGo blocks of 30s duration (20 trials/block) interspersed with 30s rest. Reaction time (RT) and accuracy (omission-Om and commission-Cm errors) results were the average of the 3 Go/NoGo blocks. During performance of the Go/NoGo blocks, changes in oxygenated (O2Hb) and deoxygenated (HHb) haemoglobin concentrations were measured by a fNIRS system (Oxymon MkIII, Artinis Medical Systems) covering the bilateral PFC regions. Results/Discussion: Clinical motor performance (UPDRSIII) improved from OFF (31) to ON (20). RT during Go and NoGo was $backslash$textasciitilde40ms faster in OFF (460 and 364ms) than ON (516 and 407ms). Furthermore, the NoGo condition increased misses (Om) in ON (7%) than OFF (0%); while false alarms (Cm) were similarly increased in ON (27%) and OFF (30%). The Go and NoGo conditions increased bilateral PFC activation (i.e., increase in O2Hb and decrease in HHb). However, there was a general decrease in PFC activation in OFF relative to ON, and this was more obvious in Go than NoGo (see Fig. 1) Conclusion: These preliminary results indicate that STN-DBS modulates neurovascular responses in the bilateral PFC that are associated with response inhibition.