***The present project aims to test the hotly debated hypothesis that, in humans, the inhibitory control of arm movements relies upon a right-lateralized network, in particular of the right subthalamic nucleus (STN)***
To assess the role of this subcortical brain region, we took advantage of a relatively rare model, i.e. advanced Parkinson’s patients who received unilateral deep-brain stimulation (DBS) of the STN either of the left (n=10) or of the right hemisphere (n=10). We gave them a countermanding reaching task, and we compared patients’ performance in two experimental conditions, DBS-ON and DBS-OFF. In addition, we also tested 22 age-matched healthy participants.
As expected, we found that inhibitory control is impaired in Parkinson’s patients with respect to healthy participants. ***However, neither reactive or proactive inhibitory control is improved when either the right or the left DBS is active***.
Therefore, our findings do not support the hypothesis according to which the right STN plays a key role in inhibitory control. Instead, they suggest that this executive function relies on the cooperation between the two STN. Furthermore, these findings seem to suggest that, at least as far as inhibitory control is concerned, it is better to implant DBS bilaterally than unilaterally.
*These data have been taken by the equipe led by Giovanni Mirabella at the IRCCS Neuromed Hospital, Pozzilli(IS).*
