The analysis of EEG microstates offers a valuable approach for investigating large-scale brain networks and dynamics. Beyond the commonly reported "canonical microstates," prior literature has identified another distinct topography: the vertical topography (VT). This VT is characterized by a prominent straight line dividing positive and negative values, extending from the nasion to the inion. Notably, our own simultaneous EEG/fMRI and shielded cabin EEG data, collected from 77 participants, also revealed the presence of this topography. Based on our subsequent analyses of both human and phantom data, we conclude that VT partly represents artifacts arising from unspecified movements of the EEG cap and its metallic components. This conclusion is strongly supported by our evaluation of VT's spatiotemporal characteristics, derived from EEG recorded under diverse conditions. Specifically, we found a significant correlation between framewise displacement (obtained from human EEG/fMRI) and VT's temporal characteristics. Therefore, we advocate for a prudent interpretation of VT when it appears in data. Its mere existence as a resulting topography can impact the spatiotemporal parameters of other microstates and even distort the shapes of the other topographies.

• Keywords
• EEG, artifacts, microstate analysis, microstates, simultaneous EEG/fMRI,
• MeSH
• Artifacts * MeSH
• Adult MeSH
• Electroencephalography * methods   MeSH
• Phantoms, Imaging MeSH
• Humans MeSH
• Magnetic Resonance Imaging MeSH
• Brain Mapping * methods   MeSH
• Young Adult MeSH
• Brain * physiology   diagnostic imaging   MeSH
• Check Tag
• Adult MeSH
• Humans MeSH
• Young Adult MeSH
• Male MeSH
• Female MeSH
• Publication type
• Journal Article MeSH

The biological basis of the neurodegenerative movement disorder, Parkinson's disease (PD), is still unclear despite it being 'discovered' over 200 years ago in Western Medicine. Based on current PD knowledge, there are widely varying theories as to its pathobiology. The aim of this article was to explore some of these different theories by summarizing the viewpoints of laboratory and clinician scientists in the PD field, on the biological basis of the disease. To achieve this aim, we posed this question to thirteen "PD experts" from six continents (for global representation) and collated their personal opinions into this article. The views were varied, ranging from toxin exposure as a PD trigger, to LRRK2 as a potential root cause, to toxic alpha-synuclein being the most important etiological contributor. Notably, there was also growing recognition that the definition of PD as a single disease should be reconsidered, perhaps each with its own unique pathobiology and treatment regimen.

• Publication type
• Journal Article MeSH
• Review MeSH

Mechanisms of deep brain stimulation (DBS) on cortical networks were explored mainly by fMRI. Advanced analysis of high-density EEG is a source of additional information and may provide clinically useful biomarkers. The presented study evaluates EEG microstates in Parkinson's disease and the effect of DBS of the subthalamic nucleus (STN). The association between revealed spatiotemporal dynamics of brain networks and changes in oscillatory activity and clinical examination were assessed. Thirty-seven patients with Parkinson's disease treated by STN-DBS underwent two sessions (OFF and ON stimulation conditions) of resting-state EEG. EEG microstates were analyzed in patient recordings and in a matched healthy control dataset. Microstate parameters were then compared across groups and were correlated with clinical and neuropsychological scores. Of the five revealed microstates, two differed between Parkinson's disease patients and healthy controls. Another microstate differed between ON and OFF stimulation conditions in the patient group and restored parameters in the ON stimulation state toward to healthy values. The mean beta power of that microstate was the highest in patients during the OFF stimulation condition and the lowest in healthy controls; sources were localized mainly in the supplementary motor area. Changes in microstate parameters correlated with UPDRS and neuropsychological scores. Disease specific alterations in the spatiotemporal dynamics of large-scale brain networks can be described by EEG microstates. The approach can reveal changes reflecting the effect of DBS on PD motor symptoms as well as changes probably related to non-motor symptoms not influenced by DBS.

• Publication type
• Journal Article MeSH