Figure 1.

Experimental protocol. (A) Timeline of one individual trial of the reaching task performed on a tactile monitor with a pen. In each trial, the patient is instructed to point at the start button to initiate the trial, reach to the red target when the Go-cue is shown, and back to the start button when the target disappears, as quickly as possible. (B) Timeline for the whole experimental session which consists of eight counterbalanced blocks in four different stimulation conditions, with two blocks in each condition. Each block contains 15 trials of reach-return movements followed by 20 s of finger-tapping movements. (C) Schematic of the adaptive deep brain stimulation (ADBS) system which consists of bipolar measurement of subthalamic nucleus (STN) local field potentials (LFPs), real time estimation of beta amplitude and monopolar stimulation delivered to one of the middle contacts, while the patient is comfortably seated on a chair and performs the tasks. (D) 3D reconstruction in coronal (left), axial (middle) and sagittal (right) views of all analysed DBS leads localized in standard Montreal Neurological Institute (MNI)-152_2009b space using Lead-DBS.^28,29 Electrodes in the left hemisphere were mirrored to the right hemisphere. The result confirmed that most of the tested electrodes clustered in a sweet spot that has been suggested to provide optimal overall motor improvement for Parkinson’s disease with DBS (shown in green).³⁰ KCH = King’s College Hospital; SGH = St George’s Hospital.