This Article Full Text (PDF) All Versions of this Article: 1545968308328730v1 23/5/486    most recent References Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Saved Citations Download to citation manager Request Permissions Request Reprints Add to My Marked Citations Citing Articles Citing Articles via Scopus Google Scholar Articles by Blicher, J. U. Articles by Nielsen, J. F. PubMed PubMed Citation Articles by Blicher, J. U. Articles by Nielsen, J. F. Social Bookmarking                         What's this?

Cortical Excitability in Chronic Stroke and Modulation by Training: A TMS Study

CFIN, Department of Neuroradiology, Aarhus University Hospital, Aarhus, Denmark, jbli{at}ki.au.dk, Hammel Neurorehabilitation and Research Centre, Aarhus University Hospital, Aarhus, Denmark

Johannes Jakobsen, MD, DMSc

Department of Neurology, Aarhus University Hospital, Aarhus, Denmark

Grethe Andersen, MD, DMSc

Department of Neurology, Aarhus University Hospital, Aarhus, Denmark

Jørgen Feldbæk Nielsen, MD, DMSc

Hammel Neurorehabilitation and Research Centre, Aarhus University Hospital, Aarhus, Denmark

Background. A possible role for GABA in regulating cortical plasticity after stroke has been proposed. Objective. To investigate changes in intracortical inhibitory and facilitatory circuits in the affected hemisphere more than 6 months after stroke, as well as modulation of excitability by a single training session. Methods. A total of 22 patients >6 months after stroke were compared to age- and gender-matched healthy participants. Cortical excitability was assessed by transcranial magnetic stimulation (TMS), including paired-pulse stimulation, before and up to 30 minutes after a single 15-minute session of 1 Hz thumb abduction-adduction movements. Results. At baseline, TMS showed decreased intracortical inhibition in the affected hemisphere of patients (P = .004) compared to healthy participants. After training a short-lasting decline in motor evoked potentials was observed in both patients (P = .002) and healthy participants (P = .06). Moreover, in healthy participants, inhibitory activity decreased up to 30 minutes after training whereas no significant change was seen in the patients. Conclusions. The findings indicate that inhibitory intracortical circuits are less active after stroke, and no change in inhibitory activity is evident after a single training session. This may indicate that intracortical disinhibition is beneficial during recovery and that an impaired capacity for modulation remains in the chronic stage of stroke.

Key Words: GABA • Neurophysiology • Stroke • Stroke recovery • Transcranial magnetic stimulation

This version was published on June 1, 2009

Neurorehabilitation and Neural Repair, Vol. 23, No. 5, 486-493 (2009)
DOI: 10.1177/1545968308328730


CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?