The cutaneous contribution to the hamstring flexor reflex in the rat: an electrophysiological and anatomical study

doi:10.1016/0006-8993(84)91216-2

Brain Research

Volume 303, Issue 2, 15 June 1984, Pages 299-312

https://doi.org/10.1016/0006-8993(84)91216-2 Get rights and content

Abstract

The location and properties of the cutaneous receptive fields responsible for detecting the flexor withdrawal reflex in the posterior head of biceps femoris (pBF) and semitendinosus (ST) components of the hamstring muscle have been examined in unanaesthetized decerebrate rats, spinalized at T10-T11. Single α-motoneurone efferents were recorded from the nerve to pBF and the principal head of ST and their responses to ipsi- and contralateral hindlimb skin stimulation investigated. The efferents to both muscles characteristically ha had a low or absent background discharge and they all had mechanoreceptive fields on the ipsilateral foot. The mechanical threshold of these fields was high with no response to light touch or brush. Fifty-four percent of these units also had a smaller and weaker contralateal mechanoreceptive field. The only apparent difference between ST and pBF efferents was that more ST efferents had contralateral fields than pBF units. Noxious, hot and cold thermal stimuli applied to the ipsilateral foot activated 56% of the efferents. Mustard oil, a chemical irritant, produced a long-lasting flexor response when applied to the ipsilateral foot. The responses of these efferents to stimulation of Aβ, Aδ and C cutaneous afferents in the sural nerve were also studied. Short latency reflexes were elicited in all efferents by Aβ inputs, longer latency reflexes were elicited in 64% by Aδ inputs and very long latency refponses with long afterdischarges were found in 73% of the units to C inputs. Retrograde labelling of the hamstring motoneurones with WGA-HRP indicated that they lay in ventrolateral lamina IX extending from the caudal portion of the third lumbar segment to the junction of the 5th and 6th lumbar segments. Transganglionic labelling of small diameter primary afferent terminals in the dorsal horn of cutaneous nerve innervating the foot revealed that the longitudinal distribution corresponded closely with that of the hamstring motor nucleus. The flexor reflex in the spinal rat provides a useful model therefore, for studying hiow the input in nociceptive afferents is processed and transformed within the spinal cord, to produce appropriate outputs.

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^*: Present address: Department of Anatomy, University of California, Irvine, CA 92717, U.S.A.

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The cutaneous contribution to the hamstring flexor reflex in the rat: an electrophysiological and anatomical study

Abstract

Exp. Neurol.

Trends Neurosci.

Brain Research

Exp. Neurol.

Exp. Neurol.

Brain Research

Integration in spinal neuronal systems

Handbook of Physiology of the Nervous System

Facilitatory interaction between cutaneous afferents from low threshold mechanoreceptors and nociceptors in segmental reflex pathways for alpha-motoneurones

Brain Research

Alterations in connections between muscle adn anterior horn motoneurones after peripheral nerve repair

Science

Progressive changes in efferent unit responses to repeated cutaneous stimulation in spinal cats

J. Neurophysiol.

Cutaneous mechanoreceptors and nociceptors

A comparison of peripheral and rubrospinal synaptic input to slow and fast twitch motor units of triceps surae

J Physiol. (Lond.)

Primary afferent depolarization and flexor reflexes produced by radiant heat stimulation of the skin

J. Physiol. (Lond.)

Subliminal fringe in spinal flexion

J. Physiol. (Lond.)

Studies of spasticity and of changes in flexion reflex with repetitive cutaneous stimulation in spinal man

Brain

Spinal and trigeminal mechanisms of nociception

Ann. Rev. Neurosci.

Synaptic actions in motorneurones by afferents which may evke the flexion reflex

Arch. ital. Biol.

An experimental analysis of the motor-cell columns in the vervical enlargement of the spinal cord of the albino rat

J. comp. Neurol.

The rule of reflex response in the limb reflexes of the mammal and its exceptions

J. Physiol. (Lond.)

Habituation of the flexor reflex in the rat

J. Physiol. (Lond.)

Afferent and efferent connections of the rat tail flick reflex (A model used to analyze pain control mechanisms)

J. comp. Neurol.

Excitatory and inhibitory skin areas for flexor and extensor motoneurones

Acta physiol. scand.

Crossed spinal reflex actions evoked by volleys in somatic afferents

Acta physiol. scand.

Differential supraspinal control of synaptic actions evoked by volleys in the flexion reflex afferents in alpha motoneurones

Acta physiol. scand.