Negative Dorsal Root Potential Research Articles

Potential changes inside central afferent terminals secondary to stimulation of large- and small-diameter peripheral nerve fibers.

Potential changes inside central afferent terminals secondary to stimulation of large- and small-diameter peripheral nerve fibers.C J Hodge JrC J Hodge JrPublished Online:01 Jan 1972https://doi.org/10.1152/jn.1972.35.1.30MoreSectionsPDF (2 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByDemonstration of the synaptic origin of primary afferent depolarization (PAD) in the isolated spinal cord of the hamsterBrain Research, Vol. 341, No. 2Long latency spinal cord dorsum potential; suppression by intrathecal morphine and enkephalin analogBrain Research, Vol. 304, No. 2Do opioid peptides mediate a presynaptic control of C-fibre transmission in the rat spinal cord?Neuroscience Letters, Vol. 29, No. 1GABAergic terminals are presynaptic to primary afferent terminals in the substantia gelatinosa of the rat spinal cordBrain Research, Vol. 141, No. 1The role of gaba in primary afferent depolarizationProgress in Neurobiology, Vol. 9, No. 4Effects of activity in non-myelinated afferent fibres on the spinocervical tractBrain Research, Vol. 98, No. 2The role of γ-aminobutyric acid as a mediator of positive dorsal root potentialsBrain Research, Vol. 76, No. 1Relationships between pre- and postsynaptic effects of A and C fiber inputs to dorsal horn of M. MulattaExperimental Neurology, Vol. 40, No. 1Positive dorsal root potentials evoked by stimulation of the brain stem reticular formationBrain Research, Vol. 54Two negative dorsal root potentials evoke a positive dorsal root potentialBrain Research, Vol. 55, No. 1Interactions of cutaneous myelinated (A) and non-myelinated (C) fibres on transmission through the spinocervical tractBrain Research, Vol. 53, No. 1Intraspinal latency, cutaneous fiber composition, and afferent control of the dorsal root reflex in catBrain Research, Vol. 47, No. 2 More from this issue > Volume 35Issue 1January 1972Pages 30-43 https://doi.org/10.1152/jn.1972.35.1.30PubMed5008723History Published online 1 January 1972 Published in print 1 January 1972 Metrics

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

1. The reflex effects of pulses of intense radiant heat applied to the skin of the central plantar pad have been studied in unanaesthetized (decerebrate) spinal cats.2. Pad heat pulses produced flexion of the ipsilateral hind limb and increased ipsilateral flexor monosynaptic reflexes, due to post-synaptic excitation of flexor alpha motoneurones. These effects were accompanied by reduction of extensor monosynaptic reflexes and post-synaptic inhibition of extensor motoneurones.3. Ipsilateral (and contralateral) pad heat pulses consistently evoked negative dorsal root potentials (DRPs) as well as increased excitability of both cutaneous and group Ib muscle afferent terminals. The excitability of group Ia afferents was sometimes also increased during pad heat pulses, but to a lesser extent.4. Pad heat pulses produced negative DRPs in preparations in which positive DRP components could be demonstrated following electrical stimulation of both skin and muscle nerves.5. The motor and primary afferent effects of heat pulses always accompanied one another, beginning after the pad surface temperature had reached rather high levels (usually 48-55 degrees C).6. Negative DRPs increased excitability of cutaneous and group Ib afferents, and motoneurone activation produced by pad heat pulses was essentially unmodified when conduction in large myelinated afferents from the central plantar pad was blocked by cooling the posterior tibial nerve trunk.7. It is concluded that adequate noxious activation of cutaneous afferents of small diameter produces primary afferent depolarization in a variety of large diameter afferent fibres, as well as post-synaptic effects in alpha motoneurones.

Primary afferent depolarization evoked by a painful stimulus.

Pulses of intense radiant heat applied to the plantar pad of unanesthetized spinal cats produced negative dorsal root potentials, increased excitability of cutaneous A fibers, and marked activation of ipsilateral flexor motoneurons. The same effects were obtained during cold block of A fiber conduction in the appropriate peripheral nerve. We conclude that adequate noxious activation of cutaneous C fibers depolarizes cutaneous A fibers.