The location of spinal neurons with long descending axons (long descending propriospinal tract neurons) in the cat: A study with the horseradish peroxidase technique

Abstract

The distribution spinal neurons with long descending axons was studied in the cat by means of retrograde transport of horseradish peroxidase. Labeled neurons appeared bilaterally in the cervical and the thoracic cord following injections in the lumbosacral cord. In some cases hemisections were made rostrally and contralaterally to the injections in an attempt to determine whether or not the axons crossed. Neurons with uncrossed descending axons were located in laminae I, V, VII and VIII. Lamina I neurons were present in all the spinal segments. In lamina V labeled neurons were distributed mainly laterally in the cervical cord but medially and laterally in the thoracic cord. In the upper cervical and the thoracic cord laminae VII and VIII neurons were distributed very densely along the lateral cord, accounting for 30 and 40 of the total labeled neurons, respectively. In the cervical enlargement they were located in the middle part of lamina VII and in lamina VIII, accounting for about 25% of the total labeled neurons. Neurons with crossed descending axons were found in laminae V, VII and VIII, in the medial part of lamina VII including the intermediomedial nucleus of the thoracic levels and close to the central canal. Lamina V neurons were very small in number. The largest collections of labeled neurons were present in the medial part of laminae VII and VIII. They accounted for about 45% to 55% and 37% of the total in the cervical and the thoracic cord. These neurons may function as the long spinal reflex paths for forelimb-hindlimb synergies and the intercalated paths between the supraspinal descending tracts and the spinal motor centers.

Bidirectional Neurones in the Cervical Enlargement of the Cat Spinal Cord with Axons Descending to Sacral Segments and Ascending to the Cerebellum and the Lateral Reticular Nucleus

“…It is worth noting that most of the authors cited show that axons interconnecting spinal centres controlling limb muscles run in the lateral funiculi. The ipsilateral andÏor contralateral course of axons demonstrated in this and previous anatomical and electrophysiological studies (Matsushita et al 1979;Alstermark et al 1987a;Verburgh et al 1989;Krutki, 1997), as well as the existence of spinal collaterals of long descending propriospinal neurones (Krutki et al 1998), points to the fact that forelimb-hindlimb coordination concerns all four limbs in a more complex manner than has been reported before.…”

Activity of descending propriospinal axons in the turtle hindlimb enlargement during two forms of fictive scratching: phase analyses

“…This finding is somewhat surprising, because studies of scratching have generally focused on ipsilateral neural circuitry. On the other hand, there are many propriospinal neurons with descending crossed axons in turtles (Kusuma and ten Donkelaar, 1980;Berkowitz and Stein, 1994a), as well as in lampreys (Buchanan, 1982;Ohta et al, 1991), embryonic tadpoles (see Roberts, 1989) embryonic newts (Harper and Roberts, 1993) goldfish (Fetcho, I99 1), lizards (ten Donkelaar and de Boer van Huizen, 1978;Kusuma and ten Donkelaar, 1980) chicks (Oppenheim et al, 1988) and mammals (Burton and Loewy, 1976;Molenaar, 1978;Molenaar and Kuypers, 1978;Matsushita et al, 1979;Menetrey et al, 1985;Hongo et al, 1989;Cassidy and Cabana, 1993). In addition, during turtle fictive scratching evoked by unilateral tactile stimulation, some hindlimb muscle nerves on the opposite side of the body are often activated with a clear rhythm ( Fig.…”

Spinal cord stimulation modulates intraspinal colorectal visceroreceptive transmission in rats

“…Neuroanatomical and electrophysiological studies show that cell bodies of upper cervical propriospinal neurons have projections to the caudal spinal cord of monkeys (Burton and Loewy 1976), cats (Matsushita et al 1979;Yezierski et al 1980), and rats (Menetrey et al 1985;Miller et al 1998). Chemical and electrical activation of cell bodies in C1-C2 segments generally suppress responses of thoracic spinal neurons to noxious cardiac, pulmonary, and esophageal stimuli and to splanchnic nerve stimulation in rats (Poree and Schramm, 1992;Qin et al 2004;.…”