Search

Keywords: Parkinson's disease psychosis; non-motor symptoms; illusions; sensorimotor processing; procedural activities EN Parkinson's disease psychosis non-motor symptoms illusions sensorimotor processing procedural activities 127 129 3 01/05/22 20220101 NES 220101 The presence hallucination (PH) is the sensation that somebody is nearby when no one is actually there. Affecting up to 60% of patients with Parkinson's disease (PD) and occurring early, PHs are clinically relevant for indicating potential negative clinical outcome.1-3 Recently, we have induced PHs safely in patients with PD by generating sensorimotor conflicts while patients repeatedly actuated a robotic device providing tactile feedback.4 Patients with symptomatic PHs were more sensitive to such sensorimotor stimulation than those without. The two patients were recruited in Switzerland from La Tour Hospital (Geneva) and Geneva University Hospital and were identified in the setting of an ongoing study on hallucinations in PD. [Extracted from the article]

Background: The ability to recognize whether sensory consequences have been self-generated or externally produced is an important element of motor control and self-monitoring. Deficits in self-monitoring have been proposed to cause abnormal bodily experiences and psychotic symptoms such as hallucinations. A recent study designed a robotic system that applies sensorimotor stimulation in healthy subjects and safely induces mild presence hallucinations (PH) and passivity experiences (Blanke et al., 2014). PH are defined as the sensation that someone is close by when actually no one is present and passivity experiences are characterized by perceptions or beliefs that an external agent is controlling one’s actions, perceptions, and/or thoughts. Although, both symptoms occur in schizophrenia and Parkinson’s disease, their neural mechanisms are unknown. Methods: Here, we first investigated the neural mechanisms of PH and passivity experiences in 25 healthy subjects. We developed a new MR-compatible robotic system able to generate the aforementioned sensorimotor conflicts, while recording subjects’ brain activity using fMRI. In addition, we applied lesion network mapping to 11 neurological patients with symptomatic PH and compared both populations to find a common PH network. In a final step, we investigated the relevance of the PH network by analyzing the connectivity of the PH network in resting state fMRI data from 58 psychotic patients. Results: We first evaluated the regions associated with the general sensorimotor conflict, which revealed the left sensorimotor area, the left putamen, the right inferior parietal lobule and the right cerebellum. Then, we analyzed the regions that were more activated during the condition eliciting PH and passivity experiences and found the inferior frontal gyrus (IFG), the insula, the superior medial gyrus and the middle temporal gyrus (MTG). Comparison of these two networks with the symptomatic PH network in neurological patients highlighted the IFG, the MTG and the vPMc. The resting state analysis within those regions in psychotic patients revealed no global differences between the groups but a functional connectivity decrease between MTG and IFG (bilaterally) specific for psychotic patients experiencing passivity experiences. Discussion: Collectively, we showed that through the use of a robotic system generating sensorimotor conflicts, the neural correlates of induced-PH and passivity experiences can be studied in healthy subjects in a controlled manner. In addition, we found two networks associated with induced-PH and passivity experience. Of these regions, three were also recruited in patients with PH of neurological origin, forming the PH network. MTGIFG connectivity in the PH network was altered selectively in psychotic patients with passivity experiences, revealing the relevance of the neural mechanisms of PH and passivity experiences in psychosis. [ABSTRACT FROM AUTHOR]

Background: The 22q11.2 deletion syndrome (22q11DS) represents one of the highest genetic risk factors for developing schizophrenia. About 30% of individuals develop symptoms like hallucinations, thought disorders, passivity symptoms or loss of agency. These symptoms could be driven by abnormal sensorimotor predictions associated with the misattribution of self-related events to external sources (Frith, 2005). We developed a robotic device altering sensorimotor processing in healthy subjects and inducing mild to moderate hallucinations (presence hallucinations - PH) and passivity experiences (Blanke et al., 2014). Using this new device and procedure, we tested the sensitivity of individuals with 22q11DS to sensorimotor conflicts provided by the robot and their proneness in experiencing robot-induced PH and related passivity experiences as compared to healthy controls. Methods: Thirty-eight individuals with 22q11DS and 21 controls moved, with the hand, a robotic device placed in front of them. A second robot placed behind them reproduced their movements, thus delivering tactile feedback on their back either synchronously (0ms between the movement and the touch, sync) or asynchronously (delay of 500ms, async) (Blanke et al., 2014). Participants rated the strength of robot-induced PH, passivity experiences that they felt during robot manipulation, and control items. Occurrence and severity of clinical symptoms were assessed. Results: Subjective ratings following robot manipulation were analysed, and age was used as covariate. In the asynch condition, participants reported significantly stronger loss of agency over their hand movements and there was a trend towards a significant interaction between group and conditions for loss of agency with control subjects experiencing more loss of agency in the asynchronous condition than 22q11DS participants. A trend for significance was also observed whereby all subjects reported stronger PH in the asynchronous condition than in the synchronous condition. No significant group effect was observed for the subjective ratings associated with the robot manipulation. For the 22q11DS group, severity scores for items of unusual thought content/delusional ideas of the Structured Interview for Prodromal Syndromes positively and significantly correlated with ratings of robot-induced PH and loss of agency in the async condition. Passivity experiences during the async condition (i.e., the subjective impression that someone else was touching their back) significantly correlated with severity scores for perceptual abnormalities/hallucinations items. Discussion: Experimental induction of sensorimotor conflicts caused mild altered mental states in individuals with 22q11DS as reported for controls. Both 22q11DS and control groups showed more sensitivity to the asynchronous condition during which they perceived loss of agency and passivity over their own actions, suggesting that the robotic stimulations disrupted self-other demarcation. In 22q11DS individuals, induced-PH, passivity experiences and loss of agency felt during the robot manipulation was associated to unusual thought content and abnormal perception. Taken together, our results suggest that 22q11DS is an interesting model to study the development of prodromal signs of psychosis at a very early stage before the onset of schizophrenia. [ABSTRACT FROM AUTHOR]

Introduction: Parkinson's Disease (PD) may lead to cognitive symptoms, including visuo-spatial attentional deficits such as unilateral spatial neglect (USN). Although there is some evidence for USN in PD patients, especially in those with left-sided onset of motor-symptoms (LPD), previous studies revealed inconsistent and highly variable results in neglect tasks using line bisection and have not systematically compared LPD with RPD (PD patients with right-sided onset) or healthy controls (HC)., Methods: We designed a fully automatized online web-based line bisection task and tested a group of 170 PD patients (81 RPD, 66 LPD) and 45 HC., Results: Our data reveals (1) a rightward bias on line bisection in LPD compared to HC and RPD, (2) right-sided pseudoneglect in HC as well as RPD. Our data also reveals that (3) PD patients, independent of the primarily affected side, are more variable in their line bisections., Conclusion: These data provide robust evidence for systematic changes in visuo-spatial perception in PD and present a new online diagnosis and monitoring tool for USN to evaluate patients at their home., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)