Objective: To characterize the features of the activity of single neurons of the subthalamic nucleus associated to impulsive-compulsive behaviors (ICBs) in Parkinson’s Disease (PD).

Background: A significant fraction of PD patients develops ICBs. The basal ganglia are known to be involved in decision making, but which dysfunctions of neuronal dynamics are associated to ICBs is still unclear.

Method: During deep brain stimulation implants, exploratory microrecordings are performed to assess the optimal target. We extracted offline single-neuron activity from these recordings for 12 PD patients with ICB (ICB+) and 12 PD patients without (ICB-). The activity of each neuron was described through the analysis of firing patterns, bursting activity, and oscillatory activity [1]. The features carrying more information about the patient conditions were then combined in a support vector machine decoder identifying the condition of the patient. The analysis was then repeated considering only ventral or dorsal neurons to assess the role of functional STN subdivisions.

Results: Neurons in ICB+ patients were associated to a decreased burstiness compared to those in ICB- patients, as identified through the shape factor of the inter-spike interval distribution [2] and the intra-burst firing frequency. Also, ICB+ neurons displayed weaker beta oscillatory activity, as well as less coherence with the local background beta activity. A decoder based on the combination of the fraction of non-bursting neurons and on beta coherence correctly discriminated ICB+ and ICB- patients with a performance above 80%.
Interestingly, the same decoding performance was achieved if considering only neurons in the ventral area of the STN, while neurons in the dorsal area did not display significant differences between the two conditions.

Conclusion: Neurons in the ventral area of STN display specific dynamics associated to ICB in PD. In particular, in drugs off condition, classic PD markers as beta oscillations and bursts are less present in the neurons of ICB patients.

References: [1] Micheli, F., Vissani, M., Pecchioli, G., Terenzi, F., Ramat, S. and Mazzoni, A. (2021), Impulsivity Markers in Parkinsonian Subthalamic Single‐Unit Activity. Mov Disord. https://doi.org/10.1002/mds.28497 [2] Vissani M, Cordella R, Micera S, Eleopra R, Romito LM, Mazzoni A. Spatio‐temporal structure of single neuron subthalamic activity identifies DBS target for anesthetized Tourette syndrome patients. J Neural Eng 2019; 16(6):066011.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/markers-of-parkinson-related-impulsive-compulsive-behaviors-in-the-activity-of-single-units-in-the-subthalamic-nucleus/