Patterned sensory nerve stimulation enhances the reactivity of spinal Ia inhibitory interneurons

Abstract

Patterned sensory nerve stimulation has been shown to induce plastic changes in the reciprocal Ia inhibitory circuit. However, the mechanisms underlying these changes have not yet been elucidated in detail. The aim of the present study was to determine whether the reactivity of Ia inhibitory interneurons could be altered by patterned sensory nerve stimulation. The degree of reciprocal Ia inhibition, the conditioning effects of transcranial magnetic stimulation (TMS) on the soleus (SOL) muscle H-reflex, and the ratio of the maximum H-reflex amplitude versus maximum M-wave (H(max)/M(max)) were examined in 10 healthy individuals. Patterned electrical nerve stimulation was applied to the common peroneal nerve every 1 s (100 Hz-5 train) at the motor threshold intensity of tibialis anterior muscle to induce activity changes in the reciprocal Ia inhibitory circuit. Reciprocal Ia inhibition, the TMS-conditioned H-reflex amplitude, and H(max)/M(max) were recorded before, immediately after, and 15 min after the electrical stimulation. The patterned electrical nerve stimulation significantly increased the degree of reciprocal Ia inhibition and decreased the amplitude of the TMS-conditioned H-reflex in the short-latency inhibition phase, which was presumably mediated by Ia inhibitory interneurons. However, it had no effect on H(max)/M(max). Our results indicated that patterned sensory nerve stimulation could modulate the activity of Ia inhibitory interneurons, and this change may have been caused by the synaptic modification of Ia inhibitory interneuron terminals. These results may lead to a clearer understanding of the spinal cord synaptic plasticity produced by repetitive sensory inputs.

Enhancement of spinal reciprocal inhibition depends on the movement speed and range of repetitive passive movement

“…In this study, the RI after effect lasted for 15 min (reciprocal Ia inhibition) and 20 min (D1 inhibition) for RPM where the movement speed was fast, the movement range was wide, and the number of movements was high. Previous studies have shown that RI enhancement lasts 10 min for PES alone (Fujiwara et al., 2011; Kubota et al., 2015; Perez et al., 2003; Takahashi et al., 2017; Yamaguchi et al., 2018), 15 min for iTBS + PES (Yamaguchi et al., 2018) and 10–20 min for anodal tDCS + PES (Fujiwara et al., 2011; Yamaguchi et al., 2016). In this study, the RI inhibition time was extended (15 to 20 min) compared with PES alone (10 min), resulting in an after effect equivalent to the combined effect of PES + iTBS or tDCS.…”

“…A number of methods have been reported to enhance RI, including PES (Fujiwara et al., 2011; Kubota et al., 2015; Perez et al., 2003; Takahashi et al., 2017; Yamaguchi et al., 2016, 2018), transcranial direct current stimulation (tDCS; Fujiwara et al., 2011; Roche, Lackmy, Achache, Bussel, & Katz, 2009, 2011; Yamaguchi et al., 2016), intermittent theta burst transcranial magnetic stimulation (iTBS; Yamaguchi et al., 2018) and RPM (Hirabayashi, Edama, Kojima, Miyaguchi, et al, 2019). In particular, PES stimulates afferent Ia fibers and enhances RI by activating Ia inhibitory interneurons and primary PAD interneurons (Fujiwara et al., 2011; Perez et al., 2003; Takahashi et al., 2017; Yamaguchi et al., 2016, 2018).…”

“…In recent years, there has been a great deal of attention paid to research on enhancement methods of RI to inhibit excessive simultaneous activity and to inhibit the excitability of antagonist muscles (Fujiwara et al., 2011; Hirabayashi, Edama, Kojima, Miyaguchi, & Onishi, 2019; Jessop, DePaola, Casaletto, Englard, & Knikou, 2013; Kubota, Hirano, Morishita, Uehara, & Funase, 2015; Noble, Pearcey, Quartly, & Zehr, 2019; Perez, Field‐Fote, & Floeter, 2003; Ritzmann, Krause, Freyler, & Gollhofer, 2018; Roche, Lackmy, Achache, Bussel, & Katz, 2009, 2011; Yamaguchi et al., 2016, 2018). At our research institute, we have previously reported on the influence of repetitive passive movement (RPM) on the cerebral cortex, with RPM currently used widely as a rehabilitation technique (Miyaguchi et al., 2013; Sasaki et al., 2017, 2018).…”

An affordable, adaptable, and hybrid assistive device for upper-limb neurorehabilitation

“…NMES can be conveniently modulated both to assist the subject in the movement and to provide perceptive cues. 29,30 In fact, if delivered at low frequencies with intensity below the motor threshold can be used for eliciting a sensory response, if delivered at intensities above the motor threshold (e.g. at 30 Hz), can induce muscle contraction regardless the ability of the subject to recruit volitionally the targeted muscle.…”

Participant attention on the intervention target during repetitive passive movement improved spinal reciprocal inhibition enhancement and joint movement function

“…In recent years, several studies have used techniques to enhance RI to inhibit excessive simultaneous muscle activity [12][13][14][15][16][17][18][19][20][21][22][23]. Approaches for enhancing RI include patterned electrical stimulation (PES) [15,17,21,23,24] and repetitive passive movement (RPM) [12,13] peripheral stimulation, which show longer intervention after-effects than brain stimulation [14,16,18,21].…”