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Deficient intracortical inhibition (SICI) during movement preparation after chronic stroke

From the Brain Imaging and Neurostimulation Laboratory (F.C.H., B.S., J.H., K.H., G.T., C.G.), Department of Neurology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; and Human Cortical Physiology and Stroke Neurorehabilitation Section (F.C.H., L.G.C.), National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD.

Address correspondence and reprint requests to Dr. Friedhelm C. Hummel, Department of Neurology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany f.hummel{at}uke.uni-hamburg.de

Background: In healthy subjects, preparation to move is accompanied by motor cortical disinhibition. Poor control of intracortical inhibitory function in the primary motor cortex (M1) might contribute to persistent abnormal motor behavior in the paretic hand after chronic stroke.

Methods: Here, we studied GABAergic short intracortical inhibition (SICI) in the ipsilesional M1 in well-recovered chronic stroke patients (n = 14; 63.8 ± 3.0 years) engaged in preparation to move the impaired hand in a reaction time paradigm.

Results: The main finding was an abnormal persistence of SICI in the ipsilesional M1 during movement preparation that was absent in age-matched controls (n = 14). Additionally, resting SICI was reduced in the patient group relative to controls.

Conclusions: Our findings document a deficit of dynamic premovement modulation of intracortical inhibition in the ipsilesional primary motor cortex of patients with chronic stroke. This abnormality might contribute to deficits in motor control of the paretic hand, presenting a possible target for correction in the framework of developing novel therapeutic interventions after chronic stroke.

Abbreviations: CS = conditioning magnetic stimulus; FDI = first digital interosseus muscle; ISI = interstimulus interval; JTT = Jebsen-Taylor Hand Function Test; M1 = primary motor cortex; MEP = motor evoked potential; RC = recruitment curves; RM-ANOVA = repeated measures analyses of variance; rMT = resting motor threshold; RT = reaction time; SICI = short interval intracortical inhibition; TMS = transcranial magnetic stimulation; US = unconditioned stimulus.

Supported by a grant from the Alexander von Humboldt Foundation (Feodor-Lynen) to F.H., by the Deutsche Forschungsgemeinschaft (SFB 550 A13 to F.H.), by the FFM of the University of Hamburg (NWF04/07 to F.H.), and by the intramural National Institute of Neurological Disorders and Stroke program, NIH.

Disclosure: The authors report no disclosures.

Medical Device: Magstim 200 magnetic stimulator (Magstim Company, Whitland, Dyfed, UK).

Received May 6, 2008. Accepted in final form February 17, 2009.

This article has been cited by other articles:

				G. Liuzzi, V. Horniss, J. Hoppe, K. Heise, M. Zimerman, C. Gerloff, and F. C. Hummel Distinct Temporospatial Interhemispheric Interactions in the Human Primary and Premotor Cortex during Movement Preparation Cereb Cortex, November 11, 2009; (2009) bhp196v1. [Abstract] [Full Text] [PDF]