Effects of Single Pinna Reflex and Dynamic Stretch on Spike

The γd motor axons that innervate the muscle spindle fibers could induce the excitation of spindle nerves.�The purpose of this study was comparing the quality effects of pinna reflex (PR) and dynamic stretch (DS) on the discharges and amplitudes of spike potentials (SPs) of spindle Ia, II, and γd axons in rat. Methods and Materials : The experimental study on the SPs discharges of 45 single caudate muscle spindle afferents and γd axons from the left side L5 roots were recorded at rest and during testing15 adult normal rats by PR and by DS. The comparison among the means SPs amplitudes of Ia, II, and γd axons in the resting discharge (RD) and after applying the PR and the DS were investigated by measuring their amplitudes. The SPs amplitudes of Ia (72±5.34μv), II (38±3.27μv), and γd (62±4.29 μv) were calculated in the RD. The obtained mean SPs amplitude difference was21% for Ia and7.7% for II in the DS more than in the PR. The SPs of Ia and II made some overlaps by using the two stimula. The γd SPs followed the SPs of Ia and II during the PR whereas this case didn’t occur for the spindle axons during the DS. The mean SPs amplitude difference of γd in the DS was 85% less than in the PR. The DS (independent to γd SPs) was as distinctive stimulus for exciting of single Ia and II fibers as the PR (dependent to γd SPs). The γd showed strong inactivity by the DS. These results would be playing role in controling the movement disorders.