Objective: To explore whether neuronal firing rate and proportion of oscillatory neuronal activity in the subthalamic nucleus (STN) is associated with severity in patients with Parkinson’s disease (PD).

Background: The pathophysiology of Parkinson’s disease remains unclear.

Methods: Twenty-two patients (M:9, F:13) with Parkinson’s disease who received subthalamic deep brain stimulation treatment were included. Microelectrode recording was performed in the STN. Single unit analysis including interspike interval (ISI) was used to study neuronal firing rate and patterns. Power spectral analysis was used to evaluate neuronal oscillation. Clinical outcome was assessed using Unified Parkinson’s Disease Rating Scales (UPDRS III) pre-and post-surgery. The groups of the early-stage and the advanced-stage were defined based on the UPDRS III scores, disease duration and the side of initial symptoms.

Results: Of total 163 neurons identified from 32 STN, there were 66 neurons with mean firing rate of 46.2±13.6 Hz obtained from the patients in the early-stage group whereas 97 neurons with mean firing rate of 59.9±17.1 Hz were obtained from patients in the advanced-stage group. Power spectral analysis showed that there were 27 (40.9%) oscillatory neurons identified from the STN neurons in the early-stage patient group (n=66) whereas 55 (56.7%) oscillatory neurons were identified from the STN neurons in the advanced-stage patient group (n=95). Further analysis found that 29.7% (8/27) ß oscillatory neurons were observed in the early-stage group whereas 52.7% (29/55) ß oscillatory neurons were observed in the advanced-stage group. When comparing the mean firing rate and proportion of oscillatory neurons in the STN of early-stage group with that of neurons in the STN of advanced-stage group, it was found that there was a 29. 6% increase STN mean firing rate of neurons (46.2±13.6 Hz vs. 59.9±17.1 Hz, P<0.05) and a 36.8% increase proportion of oscillatory neurons (40.9% vs. 56.7%) between the two groups. In particular, a 77.7% increase proportion of ß oscillatory neurons was obtained between the early-stage and advanced-stage groups (29.7% vs.52.8%, P<0.01).

Conclusions: The results strongly suggest that both subthalamic nucleus neuronal firing rate and proportion of ß oscillatory neurons increase with Parkinson’s disease progression.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/firing-rate-and-proportion-of-subthalamic-oscillatory-neurons-increase-associated-with-more-advanced-parkinsons-disease/