Abstract
BackgroundBrain activation differs according to lesion location in functional magnetic resonance imaging (fMRI) studies, but lesion location-dependent electroencephalographic (EEG) alterations are unclear. Because of the increasing use of EEG-based brain-computer-interface rehabilitation, we examined lesion location-dependent EEG patterns in patients with stroke while they performed motor tasks.MethodsTwelve patients with chronic stroke were divided into three subgroups according to their lesion locations: supratentorial lesions that included M1 (SM1+), supratentorial lesions that excluded M1 (SM1-), and infratentorial (INF) lesions. Participants performed three motor tasks [active, passive, and motor imagery (MI)] with supination and grasping movements. The hemispheric asymmetric indexes, which were calculated with laterality coefficients (LCs), the temporal changes in the event-related desynchronization (ERD) patterns in the bilateral motor cortex, and the topographical distributions in the 28-channel EEG patterns around the supplementary motor area and bilateral motor cortex of the three participant subgroups were compared with those of the 12 age-matched healthy controls.ResultsThe SM1+ group exhibited negative LC values in the active and MI motor tasks, while the other patient subgroups exhibited positive LC values. Negative LC values indicate that the ERD/ERS intensity of the ipsilateral hemisphere is higher than the contralateral hemisphere, whereas positive LC values indicate that the ERD/ERS intensity of the contralateral hemisphere is higher than the ipsilateral hemisphere. The LC values of SM1+ and healthy controls differed significantly (rank-sum test, p < 0.05) in both the supination and grasping movements in the active task. The three patient subgroups differed distinctly from each other in the topography analysis.ConclusionsThe hemispheric asymmetry and topographic characteristics of the beta band power patterns in the patients with stroke differed according to the location of the lesion, which suggested that EEG analyses of neurorehabilitation should be implemented according to lesion location.Electronic supplementary materialThe online version of this article (doi:10.1186/s12984-016-0120-2) contains supplementary material, which is available to authorized users.
Highlights
Brain activation differs according to lesion location in functional magnetic resonance imaging studies, but lesion location-dependent electroencephalographic (EEG) alterations are unclear
In healthy controls (HCs), the event-related desynchronization (ERD) in the contralateral motor cortex was stronger than that in the ipsilateral motor cortex regardless of the movement and task types, which resulted in positive laterality coefficient (LC) values
The difference in the LC values between all patients and HCs was not significant, even though all the patients represented lower LC values compared to the controls in the active and motor imagery (MI) tasks
Summary
Brain activation differs according to lesion location in functional magnetic resonance imaging (fMRI) studies, but lesion location-dependent electroencephalographic (EEG) alterations are unclear. Stroke, which is the leading cause of adult neurological disabilities in most countries [1], typically damages particular regions of a patient’s brain and results in functional impairments [2]. These impairments vary depending on the location of the lesion. The process underlying the recovery of impaired motor functions after stroke involves brain plasticity, in which motor rehabilitation therapy stimulates new neural connections and enhances cortical reorganization in order to recover normal motor function [8, 9]. Previous studies have shown that the recovery of motor function is influenced by lesion location. Feydy et al have shown that motor recovery is dependent on whether M1 is included in the
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