[PS-2.21] The effect of deep brain stimulation on statistical grammar learning in Parkinson's Disease

Kemény, F. 1 , Demeter, G. 2, 3 , Racsmány, M. 2, 3 , Valálik, I. 4 & Lukács, &. 2

1 Institute for Psychology, University of Graz, Graz, Austria
2 Department of Cognitive Science, Budapest University of Technology and Economics
3 Frontostriatal System Research Group, Hungarian Academy of Sciences
4 Department of Neurosurgery, St. John's Hospital, Budapest

Although the improvement of motor symptoms in Parkinson?s disease (PD) after deep brain stimulation (DBS) of the subthalamic nucleus (STN) is well documented, there are open questions regarding its impact on cognitive functions. We aimed to assess the effect of bilateral DBS of the STN on learning an artificial grammar. Twelve PD patients with DBS implantation (DBS group) and twelve PD wait-listed patients (control group) participated in the study. During training, participants were acoustically exposed to 58 sentences generated by a phrase structure grammar. In the test phase participants had to decide for 24 pairs of novel grammatical and ungrammatical sentences which one was more similar to the language heard before. The task was administered twice: before and after surgery (with the stimulators on) in the DBS group and with a similar time interval between the two task-administration points in the control group. Performance of the DBS group increased from T1 to T2, while learning performance of the wait-listed group did not show a significant change. Methodological concerns warrant further studies, but these results suggest that DBS may have a beneficial effect outside the motor domain, on cognitive functions that rely on pathways related to the STN.