The Journal of neuroscience : the official journal of the Society for Neuroscience
-
The immobilized, low-spinal turtle produces 3 forms of the fictive scratch reflex in response to tactile stimulation of specific sites on its body surface (Robertson et al., 1985). We used complete transections of the spinal cord at different rostrocaudal levels to reveal the minimum length of spinal cord sufficient to produce each scratch form. Additional transections revealed the progressive loss of elements of the motor pattern and the eventual loss of rhythmogenesis. ⋯ Key elements of the CPG for each of the 3 scratch forms reside in segments D7-D10. The pattern-generating capacity of the anterior half of the hindlimb enlargement is greater than the posterior half; such an asymmetric distribution of pattern-generating elements in the enlargement of the spinal cord has been described for cat scratching (Deliagina et al., 1983). These results are consistent with the hypothesis that the CPGs producing different motor patterns for the hindlimb share neuronal elements (Grillner, 1981; Robertson et al., 1985; Currie and Stein, 1988, 1989).
-
These experiments further define the organization of peptidergic pathways in the paravertebral sympathetic system of the bullfrog. Populations of axons and synaptic boutons in sympathetic ganglia 9 and 10 were found to express calcitonin gene-related peptide-like immunoreactivity (CGRP-IR) and substance P-like immunoreactivity (SP-IR). CGRP-IR is present in fibers that run through the ganglia and in boutons that make contact with almost half of the principal neurons. ⋯ In the spinal cord, the preganglionic B and C neurons that innervate ganglia 9 and 10 are located in different segments. In segments that contain preganglionic B cells, but not those that contain C cells, there were 243 +/- 37 (mean +/- SD) neurons in the intermediolateral cell column that express CGRP-IR. However, no cell bodies containing SP-IR were found in this region of the spinal cord.(ABSTRACT TRUNCATED AT 400 WORDS)