Multisensory Control of Movements at Spinal Levels and Its Supraspinal Modulation

Abstract

The main domain of spinal functions in movement control is often considered to be the evocation of more or less stereotyped reflex responses to different stimuli as the stretch reflex induced by la spindle afferents, autogenetic inhibition induced by afferents from Golgi tendon organs and retraction reflexes evoked by nociceptive afferents. However, low threshold cutaneous afferents, joint afferents and group II and III-IV muscle afferents can be assumed to be at least not of a minor importance in the control of complex normal movements. These groups of afferents, together with nociceptive afferents, have been comprised as flexor reflex afferents (FRA) since they all may evoke the flexion reflex under particular conditions. Characteristic features of these afferents are that they may use different short-and long-latency reflex pathways in common, beside so called “private” pathways, and that the interneurones of the common pathways show a wide multisensorial convergence from afferents of a great variety of receptors and a wide convergent input from descending tracts (for reviews see Lundberg, 1979; Baldissera et al., 1981; Schomburg, 1990; Jankowska, 1992).