Emotional prosody of Parkinsonians following subthalamic nucleus deep brain stimulation

Objectives: Investigation of potential differences in both perception and expression of emotional prosody between the stimulation and non-stimulation state of Parkinson's disease (PD) patients treated with subthalamic nucleus Deep Brain Stimulation (STN-DBS). Materials and methods: A group of 16 PD patients were studied for two distinct research tasks. In the first one (estimation of prosody perception), a battery of words/sentences recorded by a professional announcer was administered to them in STN-DBS-on state and they were asked to select the correct prosody each time. The procedure was repeated in the STN-DBS-off state. In the second task (estimation of prosody expression), the patients were given a second battery of recordings using the same words and sentences but in different prosody and were asked to reproduce the prosody they heard, again in STN-DBS-on/off states. Their recorded voice was later given to 50 healthy control listeners, aware of the target prosody, who evaluated the patients' ability to correctly reproduce the prosody using a 6-point scale. Results: The overall performance of the PD participants in the perception of prosody task was 45.3% and 49.8% for the DBS-on and DBS-off state respectively (p = 0.173). The specific percentages of correct perception of different types of prosody ranged from 31.3% to 62.5% and did not differ significantly between the DBS states. The rates of misclassifications were not consistently in favor of DBS-on or DBS-off state. Prosody expression in DBS-off state was rated by normal listeners as better compared to the DBS-on state. Conclusions: Regarding prosody perception, no significant differences were found either in the overall performance of PD patients or in the prosody-specific correct classification rates. However, particular stimulation states favor different misclassification directions. DBS-on state negatively influences the expression of emotional prosody in the speech of patients with Parkinson's disease. (C) 2016 Published by Elsevier Ltd.