Poster A109, Saturday, March 25, 5:00 – 7:00 pm, Pacific Concourse
The effect of deep brain stimulation of the subthalamic nucleus in Parkinson’s disease on perceptual decision-making as a function of task difficulty and speed-accuracy instructions
Yu-Ting Huang1, Saryah Alhejazi1, Artem Bunchuk1, Dilan Athauda1,2, Marwan Hariz1,2, Ludvic Zrinzo2, Tom Foltynie1,2, Patricia Limousin1,2, Maarten Speekenbrink1, Marjan Jahanshahi1; 1University College London, 2National Hospital for Neurology and Neurosurgery
It has been proposed that the subthalamic nucleus (STN) is involved in information integration and the regulation of decision thresholds, and that deep brain stimulation (DBS) of the STN would disrupt the normal function of the STN thereby inducing impulsive behaviours during decision making (Frank et al., 2007b; Bogacz et al., 2008; Cavanagh et al., 2011). The empirical evidence have demonstrated inconsistent results of the effect of STN DBS on controlling speed and accuracy thresholds during perceptual decision making processes (Green et al., 2013; Pote et al., 2016). The aim of the present study is to investigate the effect of STN DBS in Parkinson’s disease (PD) on 1) the adjustment of decision thresholds under speed and accuracy instructions, and 2) when dealing with decision conflict induced by different levels of coherence/task difficulty. Ten PD patients treated with bilateral STN DBS and twelve age-matched participants were recruited for the study. Reaction times (RTs) and error rates were measured in a motion discrimination task, the fast diffusion model was used to further analyse the behavioural data. The results showed that when under accuracy instructions, PD patients ON stimulation had faster mean RTs than OFF stimulation but there was no significant difference between PD patients ON and OFF stimulation on error rates. Parameters derived from the diffusion model showed that PD patients ON stimulation had higher decision thresholds and higher drift rate than OFF stimulation. The results thus contradict the hypothesis that STN DBS would lower decision thresholds and induce impulsive decisions.
Topic Area: PERCEPTION & ACTION: Motor control