Slowing of Frontocentral Beta Oscillations in Atypical Parkinsonism

Abstract

Diagnosis of atypical parkinsonian syndromes mostly relies on clinical presentation as well as structural and molecular brain imaging. It has not been investigated whether cortical oscillatory activity exhibits features distinguishing these syndromes. Therefore, we measured resting-state magnetoencephalography in 13 patients with corticobasal syndrome, 10 patients with progressive supranuclear palsy, 23 patients with idiopathic Parkinson’s disease and 23 healthy controls. We compared spectral power as well as amplitude and frequency of power peaks between the groups.Atypical Parkinsonism was associated with spectral slowing, distinguishing both corticobasal syndrome and progressive supranuclear palsy from age-matched healthy controls and Parkinson’s disease. Patients with atypical Parkinsonism showed a shift of beta peaks (13-30 Hz) towards lower frequencies in frontal and central areas bilaterally. A concomitant increase in theta/alpha power relative to controls was observed in both atypical parkinsonian syndromes and in Parkinson’s disease.Our results demonstrate that slowing of frontocentral beta oscillations is characteristic of atypical Parkinsonism. Spectral slowing with a different topography has previously been observed in other neurodegenerative disorders, such as Alzheimer’s disease, suggesting that spectral slowing might be an electrophysiological marker of cortical neurodegeneration. As such, it might support differential diagnosis of parkinsonian syndromes in the future.HighlightsSlowing of beta oscillations distinguishes atypical parkinsonian syndromes from healthy controls and idiopathic Parkinson’s diseaseSpectral slowing is most pronounced in frontocentral areasBeta oscillations are shifted towards lower frequencies independent of their amplitude

A sagittal gradient of pathological and compensatory effects of neurophysiological slowing in Parkinson’s disease

“…After decades of literature suggesting a pathological shift in neurophysiological signal power from high to low frequencies in patients with neurodegenerative disorders 10-12,39-41,75-84 , recent advances in capturing these multi-spectral effects have documented their anatomical distribution and relevance to clinical features 19,42,52 . In the current work, we advance this line of research in patients with Parkinson’s disease using a marker of neurophysiological slowing that recently showed associations with cognitive impairments and amyloid proteinopathy in patients with Alzheimer’s disease 52 .…”

“…Notably, beta-band (15 – 30 Hz) activity is hypersynchronous across the cortico-basal ganglia circuit in patients with PD 17,29-33 , relates to severity of motor dysfunction, and can be normalized by common therapeutics 34-38 . In the cortex of patients with PD, decades of electrophysiological studies have demonstrated a stereotyped pattern of frequency-defined neural changes relative to healthy adults, including both increased activity in low-frequency bands (e.g., delta [2 – 4 Hz] and theta [5 – 7 Hz]) and concurrent decreased power in high-frequency bands (e.g., alpha [8 – 12 Hz] and beta) 12,39-42 . This has led to a hypothesized slowing of brain activity in patients with PD, but it remains unclear whether such a neurophysiological effect relates to clinical features of the disease, and whether any such relationships are of a deleterious or compensatory nature.…”

“…This has led to a hypothesized slowing of brain activity in patients with PD, but it remains unclear whether such a neurophysiological effect relates to clinical features of the disease, and whether any such relationships are of a deleterious or compensatory nature. These multi-spectral deviations from healthy levels also comprise rhythmic and/or arrhythmic components 43-46 , for which clinical interpretation and significance for frequency-specific neuromodulation therapies remain to be established in PD 19,42,47-51 .…”

Associations between neuromelanin depletion and cortical rhythmic activity in Parkinson's disease

“…We also emphasize that few studies so far 10, 29–31, 67, 68 have considered the respective associations of rhythmic and arrhythmic neurophysiological activity with PD. Yet, pathological changes in rhythmic versus arrhythmic electrophysiology call for distinct mechanistic interpretations.…”

Mapping Subcortico‐Cortical Coupling—A Comparison of Thalamic and Subthalamic Oscillations

“…To make spectra comparable between patients, the aperiodic component was modeled using the fitting oscillations and one over f algorithm and then subtracted from the power spectrum 31 . The aperiodic and periodic components were visually inspected, and the model order was adapted, if necessary, to ensure a good model fit 32 …”