Journal of Neuroscience, Vol 6, 2259-2266, Copyright © 1986 by Society for Neuroscience
Blends of rostral and caudal scratch reflex motor patterns elicited by simultaneous stimulation of two sites in the spinal turtle
PS Stein, AW Camp, GA Robertson and LI Mortin
Simultaneous tactile stimulation of 2 sites on the body surface of a spinal
turtle elicits complex blends of the scratch forms and motor patterns
associated with each site. Our previous work has utilized 1- site
stimulation to elicit distinct forms of the scratch reflex in the spinal
turtle (Mortin et al., 1985; Robertson et al., 1985). Using this paradigm,
stimulation of a site on the shell bridge anterior to the hindlimb elicits
a rostral scratch reflex in which the dorsum of the foot rubs against the
stimulated site; stimulation of a site near the tail elicits a caudal
scratch reflex in which the heel or side of the foot rubs against the
stimulated site (Mortin et al., 1985). During each scratch cycle, the
monoarticular knee extensor muscle is active when the limb rubs against the
stimulated site, and there is rhythmic alternation between hip protractor
and hip retractor muscle activity (Robertson et al., 1985). In a rostral
scratch, the monoarticular knee extensor muscle is active during the latter
portion of hip protractor muscle activity; in a caudal scratch, the
monoarticular knee extensor muscle is active near the end of hip retractor
muscle activity. Pure- form motor patterns that are similar to those
recorded from these muscles during movement can be recorded from the
corresponding nerves in a spinal turtle immobilized with a neuromuscular
blocking agent (Robertson et al., 1985). In this paper, we describe blend
responses to simultaneous stimulation of 2 sites, one in the rostral
scratch and the other in the caudal scratch receptive field. During these
blends, the responding hindlimb rubs against both stimulated sites in one
continuous movement sequence.(ABSTRACT TRUNCATED AT 250 WORDS)