Cognitive Alterations in Motor Imagery Process after Left Hemispheric Ischemic Stroke

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Abstract

Background

Motor imagery training is a promising rehabilitation strategy for stroke patients. However, few studies had focused on the neural mechanisms in time course of its cognitive process. This study investigated the cognitive alterations after left hemispheric ischemic stroke during motor imagery task.

Methodology/Principal Findings

Eleven patients with ischemic stroke in left hemisphere and eleven age-matched control subjects participated in mental rotation task (MRT) of hand pictures. Behavior performance, event-related potential (ERP) and event-related (de)synchronization (ERD/ERS) in beta band were analyzed to investigate the cortical activation. We found that: (1) The response time increased with orientation angles in both groups, called “angle effect”, however, stoke patients’ responses were impaired with significantly longer response time and lower accuracy rate; (2) In early visual perceptual cognitive process, stroke patients showed hypo-activations in frontal and central brain areas in aspects of both P200 and ERD; (3) During mental rotation process, P300 amplitude in control subjects decreased while angle increased, called “amplitude modulation effect”, which was not observed in stroke patients. Spatially, patients showed significant lateralization of P300 with activation only in contralesional (right) parietal cortex while control subjects showed P300 in both parietal lobes. Stroke patients also showed an overall cortical hypo-activation of ERD during this sub-stage; (4) In the response sub-stage, control subjects showed higher ERD values with more activated cortical areas particularly in the right hemisphere while angle increased, named “angle effect”, which was not observed in stroke patients. In addition, stroke patients showed significant lower ERD for affected hand (right) response than that for unaffected hand.

Conclusions/Significance

Cortical activation was altered differently in each cognitive sub-stage of motor imagery after left hemispheric ischemic stroke. These results will help to understand the underlying neural mechanisms of mental rotation following stroke and may shed light on rehabilitation based on motor imagery training.

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Most cited references 49

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Removing electroencephalographic artifacts by blind source separation.

T P Jung, S Makeig, C. Humphries … (2000)

Eye movements, eye blinks, cardiac signals, muscle noise, and line noise present serious problems for electroencephalographic (EEG) interpretation and analysis when rejecting contaminated EEG segments results in an unacceptable data loss. Many methods have been proposed to remove artifacts from EEG recordings, especially those arising from eye movements and blinks. Often regression in the time or frequency domain is performed on parallel EEG and electrooculographic (EOG) recordings to derive parameters characterizing the appearance and spread of EOG artifacts in the EEG channels. Because EEG and ocular activity mix bidirectionally, regressing out eye artifacts inevitably involves subtracting relevant EEG signals from each record as well. Regression methods become even more problematic when a good regressing channel is not available for each artifact source, as in the case of muscle artifacts. Use of principal component analysis (PCA) has been proposed to remove eye artifacts from multichannel EEG. However, PCA cannot completely separate eye artifacts from brain signals, especially when they have comparable amplitudes. Here, we propose a new and generally applicable method for removing a wide variety of artifacts from EEG records based on blind source separation by independent component analysis (ICA). Our results on EEG data collected from normal and autistic subjects show that ICA can effectively detect, separate, and remove contamination from a wide variety of artifactual sources in EEG records with results comparing favorably with those obtained using regression and PCA methods. ICA can also be used to analyze blink-related brain activity.

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Mu rhythm (de)synchronization and EEG single-trial classification of different motor imagery tasks.

G. Pfurtscheller, C. Brunner, A Schlögl … (2006)

We studied the reactivity of EEG rhythms (mu rhythms) in association with the imagination of right hand, left hand, foot, and tongue movement with 60 EEG electrodes in nine able-bodied subjects. During hand motor imagery, the hand mu rhythm blocked or desynchronized in all subjects, whereas an enhancement of the hand area mu rhythm was observed during foot or tongue motor imagery in the majority of the subjects. The frequency of the most reactive components was 11.7 Hz +/- 0.4 (mean +/- SD). While the desynchronized components were broad banded and centered at 10.9 Hz +/- 0.9, the synchronized components were narrow banded and displayed higher frequencies at 12.0 Hz +/- 1.0. The discrimination between the four motor imagery tasks based on classification of single EEG trials improved when, in addition to event-related desynchronization (ERD), event-related synchronization (ERS) patterns were induced in at least one or two tasks. This implies that such EEG phenomena may be utilized in a multi-class brain-computer interface (BCI) operated simply by motor imagery.

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Neural correlates of reaching decisions in dorsal premotor cortex: specification of multiple direction choices and final selection of action.

Paul Cisek, John Kalaska (2005)

We show that while a primate chooses between two reaching actions, its motor system first represents both options and later reflects selection between them. When two potential targets appeared, many (43%) task-related, directionally tuned cells in dorsal premotor cortex (PMd) discharged if one of the targets was near their preferred direction. At the population level, this generated two simultaneous sustained directional signals corresponding to the current reach options. After a subsequent nonspatial cue identified the correct target, the corresponding directional signal increased, and the signal for the rejected target was suppressed. The PMd population reliably predicted the monkey's response choice, including errors. This supports a planning model in which multiple reach options are initially specified and then gradually eliminated in a competition for overt execution, as more information accumulates.

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Author and article information

Contributors

: Role: Editor

Journal

Journal ID (nlm-ta): PLoS One

Journal ID (iso-abbrev): PLoS ONE

Journal ID (publisher-id): plos

Journal ID (pmc): plosone

Title: PLoS ONE

Publisher: Public Library of Science (San Francisco, USA )

ISSN (Electronic): 1932-6203

Publication date Collection: 2012

Publication date (Electronic): 9 August 2012

Volume: 7

Issue: 8

Electronic Location Identifier: e42922

Affiliations

[1 ]School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China

[2 ]Department of Neurology, The Fifth People’s Hospital of Shanghai, Shanghai, China

[3 ]Med-X Research Institute, Shanghai Jiao Tong University, Shanghai, China

Hôpital Robert Debré, France

Author notes

* E-mail: stong@ 123456sjtu.edu.cn

Competing Interests: The authors have declared that no competing interests exist.

Conceived and designed the experiments: JY XLG. Performed the experiments: JY XLG ZJ LWS. Analyzed the data: JY XLG. Contributed reagents/materials/analysis tools: JY JFS SBT. Wrote the paper: JY SBT.

Article

Publisher ID: PONE-D-12-10860

DOI: 10.1371/journal.pone.0042922

PMC ID: 3415407

PubMed ID: 22912763

SO-VID: daae4af1-88aa-4ceb-bf44-d15fc7cf917b

License:

This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

History

Date received : 12 April 2012

Date accepted : 13 July 2012

Page count

Pages: 12

Funding

This work was supported by National Natural Science Foundation of China (No. 60901025, 61001015), National Basic Research Program of China (973 Program) (No. 2011CB013304), and International Science & Technology Cooperation Program of China (No. 2011DFA10950). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Cognitive Alterations in Motor Imagery Process after Left Hemispheric Ischemic Stroke

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Abstract

Background

Methodology/Principal Findings

Conclusions/Significance

Related collections

PLOS Climate

Most cited references 49

Removing electroencephalographic artifacts by blind source separation.

Mu rhythm (de)synchronization and EEG single-trial classification of different motor imagery tasks.

Neural correlates of reaching decisions in dorsal premotor cortex: specification of multiple direction choices and final selection of action.

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