Session Information
Date: Monday, October 8, 2018
Session Title: Parkinson's Disease: Neuroimaging And Neurophysiology
Session Time: 1:15pm-2:45pm
Location: Hall 3FG
Objective: Compare the response inhibition of motor process estimated through Stop Signal Reaction Time (SSRT) in Parkinson’s disease (PD) patients and healthy participants and observe the change of SSRT following dopamine replacement in PD patients.
Background: Multiple cortical and subcortical dopaminergic and noradrenergic neuronal networks, including the basal ganglia and its connections, have been implicated in the inhibition of an already initiated motor process. However, the effects of dopamine depletion and replacement on this phenomenon is not fully elucidated.
Methods: The SSRT is a validated measure for estimation of stopping ability of an already initiated movement. Participants without dementia were seated in a quiet room and instructed to press a button fitted on the top of a small box customised for measurement of SSRT. They were requested to release the button in response to a GO cue (green LED) but continue holding the button if this was followed by a STOP cue (red LED), occurring at a random interval after the green LED cue. SSRT thus calculated is independent of the response latency to the GO cue. 180 responses were recorded in all participants.
Results: We compared median response time (MRT) and optimal combination SSRT (OCSRT) between 20 healthy participants and 30 Parkinson’s disease (PD). MRT and OCSSRT was 491 ms and 361 ms respectively in PD patients. Whereas MRT and OCSSRT were 350 ms and 238 ms respectively in healthy controls (p <0.001 compared to PD). MRT and OCSSRT were 548ms and 382 in OFF phase and 494 ms and 313ms in ON phase (p<0.0001). The correlation coefficient of SSRT and MRT in PD patients were -0.097 (p=0.609).
Conclusions: The process of sudden stopping of an already initiated movement is impaired in PD patients. It is independent of visual response time. Similar stopping problem is observed clinically in ‘festination’ of gait which is a feature of PD. This defect is partially corrected by dopamine replacement therapy.
To cite this abstract in AMA style:
S. Choudhury, A. Roy, R. Singh, K. Chatterjee, B. Mondal, M. Baker, S. Baker, H.. Impaired stopping reversed through dopamine replacement in Parkinson’s disease [abstract]. Mov Disord. 2018; 33 (suppl 2). https://www.mdsabstracts.org/abstract/impaired-stopping-reversed-through-dopamine-replacement-in-parkinsons-disease/. Accessed November 21, 2024.« Back to 2018 International Congress
MDS Abstracts - https://www.mdsabstracts.org/abstract/impaired-stopping-reversed-through-dopamine-replacement-in-parkinsons-disease/