Objective: We aimed to analyze the relationship between the active electrode position within the subthalamic nucleus (STN) and subjective emotional experience in Parkinson’s disease (PD) patients treated with chronic bilateral subthalamic deep brain stimulation (STN DBS).

Background: The STN is organized into functionally overlapping dorsolateral motor, central associative, and ventromedial limbic territories. Beside the motor improvement, changes in emotional processes have been reported after STN DBS in PD(1, 2).

Methods: Twenty off-medicated, STN DBS treated PD patients rated emotional valence (from positive to negative) and arousal (from low to high) of pictures representing primary rewards and aversive fearful stimuli in two DBS conditions: with the DBS turned ON and OFF. The preoperative MRI visualizing the STN and the postoperative MRI with electrode susceptibility artefact were co-registered. Coordinates of each active electrode contact and anatomical delineation of individual STN were determined. Each STN was then fitted onto the STN reference model by Morel and further transformed into the standardized space. Relationships between the active contact positions and the affective ratings were assessed.

Results: The emotional valence and arousal ratings correlated with active electrode contact position along the anterior-posterior direction regardless of the DBS condition (p<0.05). Patients with contacts located more posteriorly rated the emotional valence and arousal from both the appetitive and the aversive pictures as more extreme. In the DBS ON-condition, patients attributed lower valence scores to aversive pictures compared with the OFF-condition, however, the ON-OFF difference was not affected by the electrode position.

Conclusions: Beside the acute effects of the STN DBS on emotional processing, emotional valence and arousal was systematically modulated by the electrode position along the anterior-posterior direction within the motor part of the STN. The basal ganglia have been implicated in motivational salience attribution and this uniform gradient-like representation of emotional experience might represent a fundamental topographic coding principle for stimulus subjective value ranging from low to high.

References: 1. Serranova T, Jech R, Dusek P, et al. Subthalamic nucleus stimulation affects incentive salience attribution in Parkinson’s disease. Mov Disord 2011;26:2260-2266. 2. Castrioto A, Lhommee E, Moro E, Krack P. Mood and behavioural effects of subthalamic stimulation in Parkinson’s disease. Lancet Neurol 2014;13:287-305.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/gradient-like-representation-of-emotional-valence-and-arousal-within-the-subthalamic-nucleus-in-parkinsons-disease/