Aim: 

The ability of rapidly adapting our motor behavior is fundamental for survival. To achieve such a high level of efficiency our motor system has to assess continuously the context in which it acts, gathering all relevant information for planning goal-oriented movements. Since in healthy subjects, planning may be affected by cognitive factors (Mirabella et al 2008 Cog Neurophsy 25: 996-1010) we wanted to check whether different cognitive contexts can affect goal-oriented movements in Parkinson's patients with a bilateral implant of deep brain stimulators (DBS) in the subthalamus (STN).

Methods: 

We asked 10 DBS Parkinson's patients to perform speeded arm reaching movement toward a visual target in 2 paradigms: a reaction time (RT) paradigm (go-only task), and a countermanding paradigm. In both tasks subjects executed the same movements, but in the countermanding task no-stop trials were randomly intermixed with stop trials. In stop trials subjects were required to withhold the ongoing movement whenever a stop-signal was shown. DBS patients performed the task twice, with both stimulators ON and with both stimulators OFF.

Results: 

We found that when the DBS were both OFF, RTs in the go-only task were faster those of no-stop trials but, differently from what happened in healthy subjects, MTs did not show the opposite trend. Turning on the DBS restores the pattern of healthy subjects.

Conclusion: 

These findings indicates that the electrical stimulation of STN allows an optimization of the movement planning.