Enhanced D1 And D2 Inhibitions Induced By Low-frequency Trains Of Conditioning Stimuli: Differential Effects On H- And T-reflexes And Possible Mechanisms.

dc.creatorMezzarane, Rinaldo André
dc.creatorMagalhães, Fernando Henrique
dc.creatorChaud, Vitor Martins
dc.creatorElias, Leonardo Abdala
dc.creatorKohn, André Fabio
dc.date2015
dc.date2015-11-27T13:46:33Z
dc.date2015-11-27T13:46:33Z
dc.date.accessioned2018-03-29T01:24:02Z
dc.date.available2018-03-29T01:24:02Z
dc.identifierPlos One. v. 10, n. 3, p. e0121496, 2015.
dc.identifier1932-6203
dc.identifier10.1371/journal.pone.0121496
dc.identifierhttp://www.ncbi.nlm.nih.gov/pubmed/25807195
dc.identifierhttp://repositorio.unicamp.br/jspui/handle/REPOSIP/202253
dc.identifier25807195
dc.identifier.urihttp://repositorioslatinoamericanos.uchile.cl/handle/2250/1302486
dc.descriptionMechanically evoked reflexes have been postulated to be less sensitive to presynaptic inhibition (PSI) than the H-reflex. This has implications on investigations of spinal cord neurophysiology that are based on the T-reflex. Preceding studies have shown an enhanced effect of PSI on the H-reflex when a train of ~10 conditioning stimuli at 1 Hz was applied to the nerve of the antagonist muscle. The main questions to be addressed in the present study are if indeed T-reflexes are less sensitive to PSI and whether (and to what extent and by what possible mechanisms) the effect of low frequency conditioning, found previously for the H-reflex, can be reproduced on T-reflexes from the soleus muscle. We explored two different conditioning-to-test (C-T) intervals: 15 and 100 ms (corresponding to D1 and D2 inhibitions, respectively). Test stimuli consisted of either electrical pulses applied to the posterior tibial nerve to elicit H-reflexes or mechanical percussion to the Achilles tendon to elicit T-reflexes. The 1 Hz train of conditioning electrical stimuli delivered to the common peroneal nerve induced a stronger effect of PSI as compared to a single conditioning pulse, for both reflexes (T and H), regardless of C-T-intervals. Moreover, the conditioning train of pulses (with respect to a single conditioning pulse) was proportionally more effective for T-reflexes as compared to H-reflexes (irrespective of the C-T interval), which might be associated with the differential contingent of Ia afferents activated by mechanical and electrical test stimuli. A conceivable explanation for the enhanced PSI effect in response to a train of stimuli is the occurrence of homosynaptic depression at synapses on inhibitory interneurons interposed within the PSI pathway. The present results add to the discussion of the sensitivity of the stretch reflex pathway to PSI and its functional role.
dc.description10
dc.descriptione0121496
dc.languageeng
dc.relationPlos One
dc.relationPLoS ONE
dc.rightsaberto
dc.rights
dc.sourcePubMed
dc.titleEnhanced D1 And D2 Inhibitions Induced By Low-frequency Trains Of Conditioning Stimuli: Differential Effects On H- And T-reflexes And Possible Mechanisms.
dc.typeArtículos de revistas


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