Is there a single beta oscillation band interfering with movement in Parkinson's disease?

Abstract

Beta oscillations in basal ganglia are considered to contribute to motor dysfunction in Parkinson's disease (PD). However, there is a high variety in frequency borders for beta oscillations between studies, which complicates the comparison and interpretation of results. Here we aimed to study the homogeneity of oscillations in the broad "beta" range (8-30 Hz) and their implication to motor functioning in PD. For this purpose, we recorded local field potentials (LFP) in the subthalamic nucleus (STN) during 34 deep brain stimulation surgeries. We identified spectral features of LFP recordings in the range 8-30 Hz to search for candidate sub-regions of stable oscillations and assessed their association with clinical scores on the contralateral side of the body and sensitivity to motor tests. Lower frequency oscillations (8-16 Hz) had a significant positive association with bradykinesia score. During voluntary movements, we observed a significant increase in LFP power in the 12-16 Hz range and a decrease in the 18-26 Hz range. We may conclude that the 8-30 Hz oscillation range includes oscillations with different functional features-sensitivity and responsiveness to movement, and clinical symptoms, which should be taken into account in further studies of beta oscillations association with PD pathophysiology. These data assume the coexistence of several frequency domains within beta range that are modulated in different ways under dopaminergic regulation and motor processing in human STN. K E Y W O R D Sbasal ganglia, beta oscillations, local field potentials, subthalamic nucleus | INTRODUCTIONParkinson's disease (PD) is the most common movement disorder that is caused by dopamine deficiency and consequent basal ganglia (BG) dysfunction. Along with levodopa therapy, deep brain stimulation (DBS) in the subthalamic nucleus (STN) has proven to be effective in treating the motor symptoms of PD.

Excessive α‐β Oscillations Mark Enlarged Motor Sign Severity and Parkinson's Disease Duration

“…When inspecting prominent peaks in the bands identified by the clustering approach, we identified two groups of patients (with and without prominent oscillations covering the α‐β range) who differed in several features. Patients with prominent lower‐frequency oscillations had significantly higher bradykinesia and rigidity scores that correspond well with previous findings 4,19 . Noteworthy, we observed prominent single‐peak β activity in all patients in both groups, whereas only about a half of patients had additional high‐amplitude α‐β oscillation peaks in their LFP recordings.…”

“…Although the exact frequency borders for particular oscillatory ranges in PD research vary considerably across the studies, only very few research studies have directly inspected probable heterogeneity of the broad β range regarding the strength of its association with motor symptoms 4,19 . Remarkably, when examining consequent frequency bins along the power spectra, both aforementioned studies have found the strongest associations with hypokinetic symptoms in the α‐β range (8–16 and 10–15 Hz, respectively), not the conventional β frequency (with the lower‐frequency border commonly set as 13 Hz).…”

“…The α oscillations were also observed in the STN during MER in both single‐unit 11 and LFP studies 4,12‐15 . Some researchers reported data indicating association between the α rhythmic activity in the STN and the temporal cortex 15,16 and its probable relation to emotional stimuli processing, 17,18 casting doubt on the contribution of α range to motor impairment in PD.…”

“…3 The α oscillations were also observed in the STN during MER in both single-unit 11 and LFP studies. 4,[12][13][14][15] Some researchers reported data indicating association between the α rhythmic activity in the STN and the temporal cortex 15,16 and its probable relation to emotional stimuli processing, 17,18 casting doubt on the contribution of α range to motor impairment in PD. Yet several lines of evidence indicate that synchrony in the lower-frequency α-β band may be associated with hypokinetic symptoms, probably even more strongly than for medium-frequency β range.…”

“…Yet several lines of evidence indicate that synchrony in the lower-frequency α-β band may be associated with hypokinetic symptoms, probably even more strongly than for medium-frequency β range. 4,11,19 However, potential interplay between oscillation subbands in the STN and their differential and cooperative contribution to PD pathology remains to be thoroughly investigated.…”