POST-TETANIC POTENTIATION OF POLYSYNAPTIC REFLEXES OF THE SPINAL CORD

The phenomenon of post-tetanic potentiation has been studied in the cat spinal cord with particular reference to polysynaptic responses. Following tetanization of dorsal roots, these reflexes show an increased response, as measured in terms of their voltage-time area, with a predominant change in the earlier reflex pathways. Both of these changes in the reflex discharge have a time course of 15 to 25 seconds. Post-tetanic potentiation is also observed in response to stimulation of a dorsal rootlet following tetanization of another rootlet in the same or in a neighboring segment. This effect can be explained by post-tetanic changes in the terminals of secondary, and possibly higher order, internuncial cells, essentially similar to those changes in the primary afferent terminals which give rise to potentiation of the monosynaptic reflex.

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Effects of tetanic stimulation on monosynaptic and dorsal root reflexes in kittens

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y91-214 ◽

1991 ◽

Vol 69 (10) ◽

pp. 1428-1435

Author(s):

Parveen Bawa

Keyword(s):

Spinal Cord ◽

Dorsal Root ◽

Monosynaptic Reflex ◽

Cutaneous Afferents ◽

Tetanic Stimulation ◽

Dorsal Root Reflex ◽

Peripheral Afferents ◽

Post Tetanic Potentiation ◽

Tetanic Depression ◽

Stimulation Of

The effects of tetanic stimulation of peripheral afferents were examined on monosynaptic reflexes and dorsal root reflexes in kittens of various ages. Concomitantly recorded monosynaptic and dorsal root reflexes resulting from the stimulation of muscle nerves showed similar post-tetanic changes, namely, predominantly post-tetanic depression in neonates and post-tetanic potentiation in older kittens or adults. However, the changes in post-tetanic responses expressed as a percentage of control in dorsal root reflexes were much smaller than those in monosynaptic reflexes. When dorsal root reflexes originating from muscle and cutaneous afferents were compared, dorsal root reflexes from the latter behaved quite differently. For all ages, post-tetanic effects on dorsal root reflexes arising from cutaneous afferents were either insignificant or very small. The possible mechanisms underlying differences in post-tetanic effects from muscle and cutaneous afferents in adults and neonates are discussed.Key words: cat, kitten, development, dorsal root reflex, monosynaptic reflex, spinal cord, post-tetanic potentiation.

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Inhibitory Action of Bulbar and Suprabulbar Reticular Formation on the Spinal Reflex Pathway

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1956.184.3.497 ◽

1956 ◽

Vol 184 (3) ◽

pp. 497-504 ◽

Cited By ~ 13

Author(s):

Chandler McC. Brooks ◽

Kiyomi Koizumi ◽

Arthur A. Siebens

Keyword(s):

Reticular Formation ◽

Inhibitory Action ◽

Inhibitory Effect ◽

Spinal Reflex ◽

Reciprocal Effect ◽

Reflex Pathway ◽

Reflex Pathways ◽

Post Tetanic Potentiation ◽

Afferent Terminals ◽

Stimulation Of

Inhibitory action of bulbar and suprabulbar reticular formation on spinal flexor and extensor reflex pathways was studied. In some instances a reciprocal effect was obtained but usually a generalized inhibition resulted. Inhibition varied in magnitude but was always present during reticular formation stimulation. In a high percentage of cases inhibition persisted for a period of 2–3 minutes after cessation of stimulation. Stimulations which blocked the reflex occasionally also had an inhibitory effect on the antidromic potential evoked by stimulation of the motor fibers involved in the reflex but in many instances the antidromic potential was actually augmented. The inhibitory stimulation also did not prevent facilitation of the antidromic potential by orthodromic stimuli. Post-tetanic potentiation was not prevented nor terminated by stimulation of the inhibitory areas of the reticular formation. This data suggest that inhibition from the reticular formation does not block afferent terminals but acts postsynaptically in such a manner, however, as not to increase axon hillock block of antidromic invasion of the soma. Effects of certain anesthetics and drugs on these phenomena were studied.

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Faculty Opinions recommendation of Primary afferent terminals acting as excitatory interneurons contribute to spontaneous motor activities in the immature spinal cord.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.13396987.14765109 ◽

2011 ◽

Author(s):

Keith Sillar ◽

Gareth B Miles

Keyword(s):

Spinal Cord ◽

Primary Afferent ◽

Motor Activities ◽

Afferent Terminals

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Time course of excitability changes of primary afferent terminals as determined by motoneuron-presynaptic interaction

Brain Research ◽

10.1016/0006-8993(69)90334-5 ◽

1969 ◽

Vol 15 (1) ◽

pp. 288-290 ◽

Cited By ~ 4

Author(s):

Emilio E. Decima ◽

Louis J. Goldberg

Keyword(s):

Time Course ◽

Primary Afferent ◽

Afferent Terminals

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An objective approach to assess colonic pain in mice using colonometry

PLoS ONE ◽

10.1371/journal.pone.0245410 ◽

2021 ◽

Vol 16 (3) ◽

pp. e0245410

Author(s):

Liya Y. Qiao ◽

Jonathan Madar

Keyword(s):

Neurological Disorders ◽

Stretch Reflex ◽

Distal Colon ◽

Saline Infusion ◽

Noxious Stimulation ◽

Trinitrobenzene Sulfonic Acid ◽

Primary Afferent ◽

Reflex Pathways ◽

Constant Rate ◽

Stimulation Of

The present study presents a non-surgical approach to assess colonic mechanical sensitivity in mice using colonometry, a technique in which colonic stretch-reflex contractions are measured by recording intracolonic pressures during saline infusion into the distal colon in a constant rate. Colonometrical recording has been used to assess colonic function in healthy individuals and patients with neurological disorders. Here we found that colonometry can also be implemented in mice, with an optimal saline infusion rate of 1.2 mL/h. Colonometrograms showed intermittent pressure rises that was caused by periodical colonic contractions. In the sceneries of colonic hypersensitivity that was generated post 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colonic inflammation, following chemogenetic activation of primary afferent neurons, or immediately after noxious stimulation of the colon by colorectal distension (CRD), the amplitude of intracolonic pressure (AICP) was markedly elevated which was accompanied by a faster pressure rising (ΔP/Δt). Colonic hypersensitivity-associated AICP elevation was a result of the enhanced strength of colonic stretch-reflex contraction which reflected the heightened activity of the colonic sensory reflex pathways. The increased value of ΔP/Δt in colonic hypersensitivity indicated a lower threshold of colonic mechanical sensation by which colonic stretch-reflex contraction was elicited by a smaller saline infusion volume during a shorter period of infusion time. Chemogenetic inhibition of primary afferent pathway that was governed by Nav1.8-expressing cells attenuated TNBS-induced up-regulations of AICP, ΔP/Δt, and colonic pain behavior in response to CRD. These findings support that colonometrograms can be used for analysis of colonic pain in mice.

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