In 2005, the Johnson Gdowski laboratory received a Schmitt research grant with co-Principal Investigator Jason Schwalb, M.D. to study sensorimotor integration in aging and in Parkinson’s Disease (PD). Working with collaborator, Jonathan W. Mink, M.D., Ph.D., this funding allowed us to develop equipment and to collect data that are being prepared for publication. The project has fostered additional collaborations and new research directions. The new proposal utilizes much of the same equipment and analysis developed under the original research proposal. However, we will incorporate new technology to expand the sophistication of experimental task presentation and control. We also include two new collaborators (Co-PI Michelle Burack, M.D., Ph.D., a board certified neurologist and movement disorders specialist and Mark Mapstone, Ph.D., a neuropsychologist).
An increasing number of reports in the literature suggest that some treatments for PD, while providing improvements in motor function, may negatively impact cognitive function and/or decision-making. Reports of patients that have been treated using dopamine replacement drugs or using deep brain stimulation (DBS) in the subthalamic nucleus (STN) have indicated an increase in the impulsivity of responses in choice/decision making tasks. These functions may be more severely impaired when decisions yield negative outcomes. This means that treated Parkinson’s patients have difficulty correcting behavior based on punishment, but can improve performance if the outcome of their decisions is rewarding. It is this aspect of sensorimotor integration and cognitive decision making that we will pursue in this study.
The purpose of the proposed experiments is to evaluate the influence of reinforcement on sensorimotor integration in patients that have been diagnosed with PD. We will evaluate the influence of positive (reward), neutral, and negative (punishment) feedback upon cued motor responses by quantifying reaction time, movement time, spatial and temporal aspects of arm movement, and the generation of errors. Our subject pool will be comprised of control individuals and patients with subthalamic nucleus deep brain stimulators (STN-DBS). PD patients with STN-DBS will be tested under various treatment conditions (on/off meds and on/off stimulation) to directly evaluate the role of basal ganglia circuitry in reinforcement-based control of motor responses. Ultimately, the goal is to use correlations between reinforcement-based motor responses and patient-specific modeling of DBS stimulus volumes to modify DBS programming to minimize adverse behavioral side effects of STN stimulation.