scholarly journals Synaptic Effect of Aδ-Fibers by Pulse-Train Electrical Stimulation

2021 ◽  
Vol 15 ◽  
Author(s):  
Shota Tanaka ◽  
Jose Gomez-Tames ◽  
Koji Inui ◽  
Shoogo Ueno ◽  
Akimasa Hirata ◽  
...  

Electrical stimulation of specific small fibers (Aδ- and C-fibers) is used in basic studies on nociception and neuropathic pain and to diagnose neuropathies. For selective stimulation of small fibers, the optimal stimulation waveform parameters are an important aspect together with the study of electrode design. However, determining an optimal stimulation condition is challenging, as it requires the characterization of the response of the small fibers to electrical stimulation. The perception thresholds are generally characterized using single-pulse stimulation based on the strength-duration curve. However, this does not account for the temporal effects of the different waveforms used in practical applications. In this study, we designed an experiment to characterize the effects of multiple pulse stimulation and proposed a computational model that considers electrostimulation of fibers and synaptic effects in a multiscale model. The measurements of perception thresholds showed that the pulse dependency of the threshold was an exponential decay with a maximum reduction of 55%. In addition, the frequency dependence of the threshold showed a U-shaped response with a reduction of 25% at 30 Hz. Moreover, the computational model explained the synaptic effects, which were also confirmed by evoked potential recordings. This study further characterized the activation of small fibers and clarified the synaptic effects, demonstrating the importance of waveform selection.

1996 ◽  
Vol 85 (5) ◽  
pp. 1176-1183 ◽  
Author(s):  
Masahiko Kawaguchi ◽  
Kiyoshi Shimizu ◽  
Hitoshi Furuya ◽  
Takanori Sakamoto ◽  
Hideyuki Ohnishi ◽  
...  

Background The clinical application of intraoperative motor-evoked potentials (MEPs) has been hampered by their sensitivity to anesthetics. Recently, to overcome anesthetic-induced depression of myogenic MEPs, multiple stimulus setups with a paired or a train of pulses for stimulation of the motor cortex were reported. However, the effects of anesthetics on MEPs induced by these stimulation techniques are unknown. Methods Bipolar electrical stimulation of the left motor cortex was carried out in 15 rats anesthetized with thiopental while the compound muscle action potentials were recorded from the contralateral hind limb. After recording of the MEP in response to the single-shock stimulation of the motor cortex, paired pulses (double pulses) or a train of three pulses (triple pulses) with an interstimulus interval of each pulse at 0.3, 0.5, 1.0, 1.5, and 2.0 ms were applied. After control MEP recording, isoflurane was administered at a concentration of 0.25 minimum alveolar anesthetic concentration (MAC), 0.5 MAC, 0.75 MAC, and 1.0 MAC, and the effects of isoflurane on the MEPs induced by single, double, and triple pulses were evaluated. Results In all animals, distinct baseline MEPs were recorded. During the administration of 0.25 MAC and 0.5 MAC isoflurane, MEPs induced by stimulation with a single pulse could be recorded in 87% and 33% of animals, respectively, and MEP amplitude was significantly reduced in a dose-dependent manner. During the administration of 0.75 MAC isoflurane, MEPs after single-pulse stimulation could not be recorded in any animals. By stimulating with paired or triple pulses, the success rate of MEP recording and MEP amplitude significantly increased compared with those after single pulse before and during the administration of isoflurane. Both the success rate of MEP recording and MEP amplitude after double- and triple-pulse stimulation decreased significantly in a dose-dependent manner during the administration of isoflurane. Conclusions Application of double or triple stimulation of the motor cortex increases the success rate of MEP recording and its amplitude during isoflurane anesthesia in rats. However, these responses are suppressed by isoflurane in a dose-dependent manner.


1991 ◽  
Vol 260 (2) ◽  
pp. R290-R297 ◽  
Author(s):  
D. H. Huangfu ◽  
P. G. Guyenet

The central pathway mediating a sympatholytic response to stimulation of the superior laryngeal nerve (SLN) was studied in halothane-anesthetized, paralyzed rats. Single-pulse stimulation of SLN inhibited lumbar sympathetic nerve discharge (LSND) with onset latency of 113 +/- 1.7 ms. LSND inhibition was markedly attenuated by bilateral microinjection of kynurenic acid (Kyn, glutamate receptor antagonist, 4.5 nmol/side) into the caudal ventrolateral medulla (CVL) or by bilateral administration of bicuculline methiodide (Bic; gamma-aminobutyric acid-receptor antagonist, 225 pmol/side) into the rostral ventrolateral medulla (RVL). In 13 of 14 cases, the baroreceptor reflex was also severely reduced. Injections of Bic or Kyn elsewhere in the medullary reticular formation were ineffective. Single-pulse stimulation of SLN inhibited 19 of 26 RVL reticulospinal barosensitive cells (onset latency 46 +/- 1.4 ms). This inhibition was attenuated (from 92 +/- 6 to 14 +/- 12%) by iontophoretic application of Bic (n = 7), which also reduced the cells' inhibitory response to aortic coarctation. The remaining seven barosensitive neurons were unaffected by SLN stimulation. In conclusion, the sympathetic baroreflex and the sympathoinhibitory response to SLN stimulation appear to be mediated by similar medullary pathways.


1996 ◽  
Vol 271 (4) ◽  
pp. R1054-R1062 ◽  
Author(s):  
F. Hayashi ◽  
D. R. McCrimmon

It was hypothesized that, because rats appear to lack a prominent disynaptic projection from the dorsal respiratory group to phrenic motoneurons (Phr), they would lack the short-latency excitation of Phr output seen in cats in response to stimulation of some cranial nerve afferents. Single-pulse superior laryngeal nerve (SLN) stimulation elicited a short-latency bilateral excitation of glossopharyngeal (IX) and hypoglossal (XII) nerves and an ipsilateral excitation of pharyngeal branch of vagus (PhX) in 67% of rats, but no excitation of Phr. Vagus (X) stimulation elicited a bilateral excitation of Phr and a predominantly ipsilateral excitation of IX and PhX. Single-pulse stimulation of SLN or X also elicited longer-latency, bilateral decreases in activity of all recorded nerves. Repetitive stimulation (50 Hz) of SLN or X suppressed inspiratory activity and prolonged expiration. Lung inflation (7.5 cmH2O) inhibited Phr and PhX activity; X stimulation inhibited Phr but prolonged PhX activity. In conclusion, rats predictably lack the SLN-induced short latency Phr excitation but exhibit other short latency reflexes for which the underlying circuitry is not clear.


1989 ◽  
Vol 13 (2) ◽  
pp. 116-122 ◽  
Author(s):  
Anton Moritz ◽  
Sharon Grundfest-Broniatowski ◽  
Laszlo Ilyes ◽  
Jerry Kasick ◽  
Gordon Jacobs ◽  
...  

Neuroscience ◽  
2010 ◽  
Vol 170 (2) ◽  
pp. 623-632 ◽  
Author(s):  
M.E. Lacruz ◽  
A. Valentín ◽  
J.J. García Seoane ◽  
R.G. Morris ◽  
R.P. Selway ◽  
...  

2013 ◽  
Vol 33 (49) ◽  
pp. 19326-19340 ◽  
Author(s):  
M. Capogrosso ◽  
N. Wenger ◽  
S. Raspopovic ◽  
P. Musienko ◽  
J. Beauparlant ◽  
...  

2001 ◽  
Vol 85 (6) ◽  
pp. 2639-2642 ◽  
Author(s):  
Kaoru Yoshida ◽  
Yoshiki Iwamoto ◽  
Sohei Chimoto ◽  
Hiroshi Shimazu

We investigated the synaptic organization responsible for the inhibition of omnipause neurons (OPNs) following stimulation of the superior colliculus (SC) in alert cats. Stimulation electrodes were implanted bilaterally in the rostral and caudal SC where a short-pulse train induced small and large saccades, respectively. Effects of single-pulse stimulation on OPNs were examined with intracellular and extracellular recordings. In contrast to monosynaptic excitatory postsynaptic potentials, which were induced by rostral SC stimulation, inhibitory postsynaptic potentials were induced with disynaptic latencies (1.3–1.9 ms) from both the rostral and caudal SC in most OPNs. Analysis of a larger extracellular sample complemented intracellular observations. Monosynaptic activation of OPNs was elicited more frequently from rostral sites than from caudal sites, whereas spike suppression with disynaptic latencies was induced by caudal as well as rostral stimulation with similar frequencies. The results imply that disynaptic inhibition is produced by activation of SC cells that are distributed over wide regions related to saccades of different sizes. We suggest that signals from these neurons initiate a saccadic pause of OPNs through single inhibitory interneurons.


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