Objective: Here we aimed to investigate heterogeneity in the neuronal activity within the subthalamic nucleus (STN) to search the association between oscillatory activity and motor signs of Parkinson’s disease (PD) within distinct neuronal patterns that are present in the STN motor area.

Background: Extensive oscillations in broadband beta frequencies in the STN contribute greatly to hypokinetic symptoms in PD and therefore are extensively studied. However, single unit activity inside the STN shows significant heterogeneity and may contribute unequally to PD pathophysiology and extensive oscillatory processes in the STN.

Method: 25 PD patients undergoing DBS surgeries in the STN were included in the study. We have recorded and isolated 829 single units and calculated several parameters of interspike intervals and bursts detected using Poisson surprise approach (S=3). We have analyzed spike trains longer than 10 sec containing more than 200 spikes. Spike trains in the data set were split into three patterns (regular tonic activity, irregular-burst activity without obvious silent periods in spike trains, pause burst activity with pauses between the bursts) using hierarchical clustering approach based on spike density histograms.

Results: SUA in the STN was grouped into three clusters – tonic, irregular-burst and pause-burst activity. It was the only pause-burst pattern where neurons oscillating in alpha, low beta and high beta range correlated positively with UPDRS-III score in the off-state and bradykinesia score on the contralateral side of the body, while theta oscillations in pause-burst neurons correlated negatively with bradykinesia score.

Conclusion: We have shown that extensive oscillatory synchronization in alpha-beta range affects predominantly pause-burst firing pattern, and that this was the only pattern demonstrating statistically significant association between the level of oscillations in the 8-30 Hz range and the severity of PD hypokinetic symptoms. The firing patterns of single unit activity inside the STN vary significantly, and we may assume that pause-burst pattern may be viewed as most implicated in PD pathophysiology and thus most informative when studying neurophysiological mechanisms of hypokinetic disorders.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/oscillatory-activity-of-pause-burst-stn-neurons-shows-an-association-with-motor-symptoms-of-parkinsons-disease/