Brain Motor Network Changes in Parkinson's Disease: Evidence from Meta‐Analytic Modeling

Abstract

Background Motor‐related brain activity in Parkinson's disease has been investigated in a multitude of functional neuroimaging studies, which often yielded apparently conflicting results. Our previous meta‐analysis did not resolve inconsistencies regarding cortical activation differences in Parkinson's disease, which might be related to the limited number of studies that could be included. Therefore, we conducted a revised meta‐analysis including a larger number of studies. The objectives of this study were to elucidate brain areas that consistently show abnormal motor‐related activation in Parkinson's disease and to reveal their functional connectivity profiles using meta‐analytic approaches. Methods We applied a quantitative meta‐analysis of functional neuroimaging studies testing limb movements in Parkinson's disease comprising data from 39 studies, of which 15 studies (285 of 571 individual patients) were published after the previous meta‐analysis. We also conducted meta‐analytic connectivity modeling to elucidate the connectivity profiles of areas showing abnormal activation. Results We found consistent motor‐related underactivation of bilateral posterior putamen and cerebellum in Parkinson's disease. Primary motor cortex and the supplementary motor area also showed deficient activation, whereas cortical regions localized directly anterior to these areas expressed overactivation. Connectivity modeling revealed that areas showing decreased activation shared a common pathway through the posterior putamen, whereas areas showing increased activation were connected to the anterior putamen. Conclusions Despite conflicting results in individual neuroimaging studies, this revised meta‐analytic approach identified consistent patterns of abnormal motor‐related activation in Parkinson's disease. The distinct patterns of decreased and increased activity might be determined by their connectivity with different subregions of the putamen. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Motor Cortical Network Excitability in Parkinson's Disease

“…Therefore, increased pre-SMA N40 amplitude may reflect changes along cortico-subcortical circuits in PD. 66,68 Our finding of increased pre-SMA TEPs in PD contrasts with that recently reported in a similar study. 46 However, while we centered the coil over the midline, Casarotto and colleagues stimulated a more lateral area, eliciting TEPs that may receive larger contributions from the dorsal premotor cortex (PMd).…”

“…1,2 However, degeneration of thalamic dopamine innervation has recently been described in PD animal models, and therefore, P30 changes in PD may reflect thalamic changes unrelated to basal ganglia abnormalities. 65 Reduced M1 P30 is consistent with the reduced motor-related M1 activation reported by neuroimaging studies 66 and provides evidence of PD-related neural dysfunction that is not confounded by differences in motor task performance because TEPs were recorded at rest.…”

Toward future adaptive deep brain stimulation for Parkinson’s disease: the novel biomarker — narrowband gamma oscillation

“…Further cross-frequency coupling (CFC) analysis revealed the abnormal CFC between the STN beta power and broadband gamma rhythm in M1. As M1 has long been implicated in the pathophysiology of PD and appeared to be one of the consistent brain areas reported in several task-based PD studies (Herz et al, 2021), it is evident that the immoderate coupling within M1 may be the representation of the cortical modification of the immoderate synchronization within the motor cortico-basal ganglia network.…”

Fading of brain network fingerprint in Parkinson’s disease predicts motor clinical impairment

“…3), may lead to the reduced contribution to the identifiability. To date, the quality of the alterations (in the sense of hypo/hyperactivation) related to the regions involved in the PD motor patterns is still debated 22 . With regard to the motor cortex, several studies reported controversial results when comparing PD patients and healthy controls.…”

“…Then, we obtained the time series of 116 regions of interest (ROIs), based on the AAL atlas 45 , using the volume conduction model proposed by Nolte 46 , and applying the Linearly Constrained Minimum Variance 47 beamformer algorithm included in the Fieldtrip toolbox 42 . The resulting time series were band-pass filtered in each canonical frequency band (i.e., delta (0.5 -4 Hz), theta (4 -8 Hz), alpha (8 -13 Hz), beta (13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30), and gamma (30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43)(44)(45)(46)(47)(48)). Only 90 ROIs were selected for further analysis, since we excluded ROIs related to the cerebellum because of low reliability.…”