Brain activity during externally and internally guided movements in patients with Parkinsons disease

An imbalance in the activity of the basal ganglia in Parkinsons disease is known to result in disturbance of the planning and initiation of mainly self-initiated voluntary movements. The effectiveness of self-initiated movements can be improved by adding an external stimulus. Despite a large number of studies in this area, the neural mechanisms of motor control of these movements and the role of the basal ganglia in their implementation remain unknown. The aim of the study was to compare brain activity during the execution of externally triggered (ET) and internally guided (IG) movements in normal state and Parkinson's disease. We used functional MRI with block designed paradigm to analyze brain activity caused by voluntary movements. Twenty healthy participants and twenty Parkinson's disease patients (OFF-state) were asked to perform hand movements in response to sound stimuli (ET) and in advance of the stimuli (IG). We showed that brain activity during externally induced movements is lateralized mainly in the contralateral hemisphere, both in normal and in Parkinson's disease. During the IG movement, brain activity was observed also in the ipsilateral hemisphere, to a greater extent in patients, which indicates difficulty in performing this test. At the same time, in patients, activation was observed not only in the posterior parts of the putamen but also in the anterior ones during IG movements. These results showed that IG movements in patients with PD were made with the participation of both sensorimotor and associative basal ganglia-thalamocortical loops. This work was supported by RFBR 19-315-90097 .