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Neurorehabil Neural Repair. 2009 Jun;23(5):486-93. doi: 10.1177/1545968308328730. Epub 2009 Feb 12.

Cortical excitability in chronic stroke and modulation by training: a TMS study.

Author information

1
Hammel Neurorehabilitation and Research Centre, CFIN, Department of Neuroradiology, Aarhus University Hospital, Aarhus, Denmark. jbli@ki.au.dk

Abstract

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.

PMID:
19221005
DOI:
10.1177/1545968308328730
[Indexed for MEDLINE]
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