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A fast and general method to empirically estimate the complexity of brain responses to transcranial and intracranial stimulations
The Perturbational Complexity Index (PCI) was recently introduced to assess the capacity of thalamocortical circuits to engage in complex patterns of causal interactions. While showing high accuracy in detecting consciousness in brain-injured patients, PCI depends on elaborate experimental setups and offline processing, and has restricted applicability to other types of brain signals beyond transcranial magnetic stimulation and high-density EEG (TMS/hd-EEG) recordings.Reproducibility in TMS–EEG studies: A call for data sharing, standard procedures and effective experimental control
A recent study by Conde, Tomasevic et al. (2019) [1] puts a spotlight on the subtleties of experimental design and analysis of studies involving TMS-evoked EEG potentials (TEPs), specifically focusing on the challenge of disentangling genuine cortical responses to TMS from those resulting from concomitant sensory activation. This is a relevant topic that the TMS–EEG community has previously identified [2] and addressed with different strategies [3–6]. Based on the similarity of the evoked EEG responses they obtained in real TMS at different sites and in sham conditions (auditory and somatosensory scalp stimulation), the authors of [1] inferred that TEPs can be significantly contaminated by the effects of concurrent, non-transcranial stimulation.Excitability of the supplementary motor area in Parkinson's disease depends on subcortical damage
Cortical dysfunctioning significantly contributes to the pathogenesis of motor symptoms in Parkinson's disease (PD).On the Cerebral Origin of EEG Responses to TMS: Insights From Severe Cortical Lesions
Transcranial magnetic stimulation combined with electroencephalography (TMS/EEG) represents a valuable tool to probe cortical excitability and connectivity. Although several procedures have been devised to abolish TMS-related artifacts, direct evidence that it is possible to record TMS-evoked potentials (TEPs) that purely reflect cortical responses to TMS are still lacking.
