The Effects of Plantar Nerve Stimulation on Long Latency Flexion Reflexes in the Acute Spinal Cat

Recently, it has been shown that knee and ankle extensor Ib afferents can reset or entrain locomotor activity by promoting extensor burst activity whilst suppressing flexor burst generation (Conway, Hultborn & Kiehn, 1987; Pearson, Ramirez & Jiang, 1992). This indicates that limb loading during stance is important in the reflex regulation of stepping and we have now investigated whether other afferent systems, which might signal limb loading, show similar reflex effects. In the acute spinal cat treated with L-Dopa, stimulation of high threshold afferents results in the generation of late and long lasting flexion reflexes (LFRs), which are believed to reflect the organisation of a spinal locomotor generator (Lundberg, 1979). In this study, we have examined whether electrical stimulation of low threshold afferents from the plantar aspect of the hind foot (including cutaneous and muscle afferents) modify the transmission of LFRs.