Outlasting corticomotor excitability changes induced by 25 Hz whole-hand mechanical stimulation

Abstract

The objective was to investigate if whole-hand mechanical stimulation (MSTIM) in the tapping-flutter frequency range induces outlasting post-stimulus changes in the hand region of the primary motor cortex. MSTIM was delivered to 12 healthy subjects for 20 min using a therapeutic stimulation device (Swisswing BMR 2000). Frequencies of 10 and 25 Hz were tested in separate sessions, and for control additionally the foot sole was stimulated at 25 Hz. Motor evoked potentials (MEPs) after single (recruitment curves) and paired-pulse transcranial magnetic stimulation (TMS) were recorded from FDI and APB muscles of the right hand. TMS assessments were carried out at baseline (T0), immediately after (T1), 30 min (T2), 1 h (T3) and 2 h (T4) after end of MSTIM. After MSTIM with 25 Hz, MEP recruitment curves were increased at all post-stimulation assessments in both muscles. The most significant effect was achieved at T3 (1 h). Intracortical inhibition was decreased within the first hour, while intracortical facilitation was increased at all post-stimulation assessments. No significant effects were found following MSTIM with 10 Hz and following foot vibration. We conclude that 20 min MSTIM with a frequency of 25 Hz induces outlasting plastic changes in the primary motor cortex. Paired-pulse stimulation further confirms that intrinsic intracortical mechanisms are involved in these changes. Spinal adaptation could be excluded (F-wave assessments). These results could be of relevance for hemiplegic patients with motor deficits, to improve the rehabilitation outcome with vibration exercise in combination with motor training.

Tactile stimulation interventions: Influence of stimulation parameters on sensorimotor behavior and neurophysiological correlates in healthy and clinical samples

“…Decreasing the intensity of one of these parameters, either frequency intensity or duration, can suffice to diminish the effect (Christova et al, 2011;Golaszewski et al, 2012). Similarly, increasing the strength of another parameter like intensity (Golaszewski et al, 2012) or frequency (Christova et al, 2011) could re-establish this effect.…”

“…Dinse et al, 2006;Höffken et al, 2007;Kalisch et al, 2007;Kalisch et al, 2008;Pilz, Veit, Braun, & Godde, 2004), or rather stimulation of the whole hand simultaneously with a specific glove to maximize the effect of coactivation (Christova et al, 2011;Golaszewski et al, 1999;Golaszewski et al, 2004;Golaszewski et al, 2010;Golaszewski et al, 2012). Few studies also stimulated other body parts, such as the palm or foot (Christova, Rafolt, Mayr, Wilfling, & Gallasch, 2010;Christova et al, 2012;Peurala et al, 2002).…”

“…The changes in M1 further resemble those in S1 in their spatial restriction. For instance, stimulation of the foot did not induce any changes in the cortical representations of upper extremities (Christova et al, 2011).…”

“…One PARAMETER CHOICE AND EFFECTIVENESS OF TACTILE STIMULATION 58 protocol applying motor stimulation at 0.67 Hz frequency on average for 1 hour in 9 sessions, prior to motor training could not affect either motor threshold, MEP amplitudes or recruitment curves (McDonnell et al, 2007), which might be due to the relatively low frequency and stimulation time. Stimulation of the whole hand at sensory intensity was only effective if it was applied at 50 Hz (2.5-3.5 % increase of motor threshold) (Golaszewski et al, 2010;Golaszewski et al, 2012), but not at 10 or 25 Hz (Christova et al, 2011).…”

“…A third group of studies applied even higher frequencies of stimulation at 50 Hz, for 30 minutes (Christova, Rafolt, Golaszewski, & Gallasch, 2011;Golaszewski et al, 2010;Kaelin-Lang et al, 2002).…”