After stroke bidirectional modulation of soleus stretch reflex amplitude emerges during rhythmic arm cycling. 2014

Rinaldo A Mezzarane, and Tsuyoshi Nakajima, and E P Zehr
Laboratory of Signal Processing and Motor Control, University of Brasïlia, College of Physical Education Brasïlia, Brazil ; Rehabilitation Neuroscience Laboratory, School of Exercise Science, Physical, and Health Education, University of Victoria Victoria, BC, Canada.

OBJECTIVE after stroke a typical presentation is exaggerated stretch reflexes (SRs) on the more affected (MA) side. The present study evaluated the contribution of presynaptic inhibition (PSI) induced by arm cycling and homosynaptic depression (HD) to the modulation of hyperreflexia at the ankle after stroke. Possible asymmetry of these effects between the MA and less affected (LA) legs was also assessed. METHODS soleus SR was conditioned by: arm cycling at 1 Hz (to increase Ia PSI); or, a preceding conditioning tendon tap applied 1 s before the test stimulus (to induce HD). The extent of conditioning effects was compared between the MA and the LA legs. RESULTS for both MA and LA legs, rhythmic arm movement induced a bidirectional effect in different participants, either increasing or decreasing SR amplitude (p < 0.05). HD had a significant effect in both legs (p < 0.05), however, the effect of both a previous muscle stretch and arm cycling was not different between the MA and the LA legs. CONCLUSIONS our data reveal a bidirectional reflex modulation induced by arm cycling that produced facilitation in some and suppression in other participants after stroke. Relative SR amplitude modulation did not differ between the LA and MA legs. We speculate that alterations in SR amplitude modulation after stroke may reflect specific changes in both presynaptic afferent transmission mechanisms and fusimotor control. CONCLUSIONS the present findings open new perspectives on the characterization of pathophysiology of stroke during the performance of functionally relevant motor tasks.

UI MeSH Term Description Entries

Related Publications

Rinaldo A Mezzarane, and Tsuyoshi Nakajima, and E P Zehr
June 2008, Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology,
Rinaldo A Mezzarane, and Tsuyoshi Nakajima, and E P Zehr
May 2010, Neuroscience letters,
Rinaldo A Mezzarane, and Tsuyoshi Nakajima, and E P Zehr
January 2001, Motor control,
Rinaldo A Mezzarane, and Tsuyoshi Nakajima, and E P Zehr
October 2011, Experimental brain research,
Rinaldo A Mezzarane, and Tsuyoshi Nakajima, and E P Zehr
February 2009, Experimental brain research,
Rinaldo A Mezzarane, and Tsuyoshi Nakajima, and E P Zehr
May 2007, Experimental brain research,
Rinaldo A Mezzarane, and Tsuyoshi Nakajima, and E P Zehr
August 1996, Journal of neurophysiology,
Rinaldo A Mezzarane, and Tsuyoshi Nakajima, and E P Zehr
August 2012, Journal of neurophysiology,
Rinaldo A Mezzarane, and Tsuyoshi Nakajima, and E P Zehr
January 2006, Somatosensory & motor research,
Rinaldo A Mezzarane, and Tsuyoshi Nakajima, and E P Zehr
February 2013, Neuroscience letters,
Copied contents to your clipboard!