Neuronal Mechanisms Underlying the Laryngeal Adductor Reflex

2011 ◽  
Vol 120 (11) ◽  
pp. 755-760 ◽  
Author(s):  
Qi-Jian Sun ◽  
Jia Min Chum ◽  
Tara G. Bautista ◽  
Paul M. Pilowsky ◽  
Robert G. Berkowitz

Objectives: Electromyographic studies of the laryngeal adductor reflex, glottal closure occurring in response to laryngeal stimulation, have demonstrated an early ipsilateral response (R1) and a late bilateral response (R2). To better define the physiologic properties of these responses, we recorded responses from expiratory laryngeal motoneurons (ELMs) in rats during stimulation of the superior laryngeal nerve (SLN). Methods: Single unit extracellular recordings were obtained from 5 ELMs, identified by their antidromic responses to recurrent laryngeal nerve stimulation and postinspiratory firing pattern, in 4 Sprague-Dawley rats. Results: Unilateral stimulation of the SLN (at 20 Hz) stopped both phrenic nerve inspiratory activity and ELM postinspiratory activity. However, the ELMs displayed robust tonic firing, consisting of non-respiratory burst activity and single action potentials. The single action potentials were identified as short-latency ones (5 to 10 ms) activated by ipsilateral SLN stimulation, with an occurrence rate of 90%, and long-latency ones (20 to 50 ms) activated by bilateral SLN stimulation, with occurrence rates of 47% on the ipsilateral side and 58% on the contralateral side. Conclusions: The R1 response appears to be the result of the short-latency action potentials, orthodromically activated by ipsilateral stimulation of the SLN. The R2 response is likely to be a result of the long-latency action potentials that can be recorded from ELMs on both sides.

1984 ◽  
Vol 52 (6) ◽  
pp. 1169-1180 ◽  
Author(s):  
J. S. Gidda ◽  
R. K. Goyal

Swallow<evoked potentials in the preganglionic vagal fibers were studied using the single<fiber recording technique in anesthetized opossums. Swallows were evoked by tactile pharyngeal stimulation or electrical stimulation of the cut central end of the superior laryngeal nerve (SLN). Swallowing activity was recorded by the mylohyoid electromyogram and esophageal motility. Sixty<six fibers were studied in which swallowing evoked action potentials. The latencies (from the onset of mylohyoid activity) of evoked responses in different fibers varied from 100 ms to 5 s. The discharge rate of the evoked response was 3<8 action potentials per burst. Each burst lasted 1.1 +/- 0.02 (SE)s. The latencies of evoked spike bursts showed a bimodal distribution. In 34 fibers the latencies were less than 1 s, and in 32 fibers the latencies ranged between 1 and 5 s; these are the short- and long-latency fibers, respectively. Short-latency fibers could easily be distinguished from long-latency fibers based on the influence of SLN-stimulus frequency. Short-latency discharges had low thresholds of activation and were sensitive to changes in the frequency of SLN stimulation, since their latencies decreased and their discharge rate increased with increasing SLN-stimulus frequency. On the other hand, the latencies and discharge rates of long-latency discharges were not modified with changing SLN stimulus frequencies. The conduction velocities of 6 short- and 9 long-latency fibers were 5.64 +/- 0.12 and 5.78 +/- 0.12 (SE) m/s, respectively (P greater than 0.05). The relationship between the latencies of swallow-evoked discharges in the short- and long-latency fibers and the esophageal smooth muscle responses suggested that the short-latency discharges may correlate with the latency of initial inhibition, and the long-latency fibers may correlate with latencies of peristaltic contractions. Based on these temporal relationships, we speculate that vagal efferent fibers showing swallow-evoked, short-latency discharges make contact with intramural inhibitory neurons. They may mediate deglutitive inhibition in the body of the esophagus, relaxation of the lower esophageal sphincter, and receptive relaxation of the fundus of the stomach. The fibers showing late discharges make contact with intramural excitatory neurons and participate in their sequential activation. This dual pathway of activation may be responsible for physiological esophageal peristalsis.


1987 ◽  
Vol 97 (1) ◽  
pp. 28-38 ◽  
Author(s):  
George S. Goding ◽  
Mark A. Richardson ◽  
Ronald E. Trachy

The laryngeal chemoreflex (LCR) was investigated in 21 piglets (ages 6 to 80 days old) with the use of physiologic and histologic techniques. The central projection of the superior laryngeal nerve (SLN) was determined in 14 animals by use of horseradish peroxidase-wheat germ agglutinin. Ipsilateral labeling of the solitary tract nucleus was seen. The caudal extent of the labeling varied with age. Sensory labeling of the nucleus ambiguus was present bilaterally in three younger animals and unilaterally in older piglets. Bilateral labeling of the nucleus dorsomedialis was seen in all ages. Apneic and cardiovascular response to water stimulation of laryngeal mucosa and the laryngeal adductor reflex (LAR) were examined in 16 piglets. Blunting of the apneic and cardiovascular response was seen after sacrifice of a single SLN. Hypoxia did not significantly affect the LAR or apnea duration in animals with only one intact SLN. A contralateral LAR was found in younger animals. Relevance to the LCR is also discussed.


1997 ◽  
Vol 106 (7) ◽  
pp. 594-598 ◽  
Author(s):  
Sina Nasri ◽  
Joel A. Sercarz ◽  
Pouneh Beizai ◽  
Young-Mo Kim ◽  
Ming Ye ◽  
...  

The neuroanatomy of the larynx was explored in seven dogs to assess whether there is motor innervation to the thyroarytenoid (TA) muscle from the external division of the superior laryngeal nerve (ExSLN). In 3 animals, such innervation was identified. Electrical stimulation of microelectrodes applied to the ExSLN resulted in contraction of the TA muscle, indicating that this nerve is motor in function. This was confirmed by electromyographic recordings from the TA muscle. Videolaryngostroboscopy revealed improvement in vocal fold vibration following stimulation of the ExSLN compared to without it. Previously, the TA muscle was thought to be innervated solely by the recurrent laryngeal nerve. This additional pathway from the ExSLN to the TA muscle may have important clinical implications in the treatment of neurologic laryngeal disorders such as adductor spasmodic dysphonia.


1979 ◽  
Vol 78 (1) ◽  
pp. 121-136
Author(s):  
GERALD E. SILVEY ◽  
IAN S. WILSON

The syncarid crustacean Anaspides tasmaniae rapidly flexes its free thoracic and abdominal segments in response to tactile stimulation of its body. This response decrements but recovers in slightly more than one hour. The fast flexion is evoked by single action potentials in the lateral of two large diameter fibres (40 μm) which lie on either side of the cord. The lateral giant fibre is made up of fused axons of 11 neurones, one in each of the last 5 thoracic and 6 abdominal ganglia. The soma of each neurone lies contralateral to the axon. Its neurite crosses that of its counterpart in the commissure and gives out dendrites into the neuropile of each hemiganglion. The lateral giant neurone receives input from the whole body but fires in response only to input from the fourth thoracic segment posteriorly. Both fibres respond with tactile stimulation of only one side. Since neither current nor action potentials spread from one fibre to the other, afferents must synapse with both giant neurones. The close morphological and physiological similarities of the lateral giant neurone in Anaspides to that in the crayfish (Eucarida) suggest that the lateral giant system arose in the ancestor common to syncarids and eucarids, prior to the Carboniferous.


1989 ◽  
Vol 62 (3) ◽  
pp. 711-722 ◽  
Author(s):  
T. Allison ◽  
G. McCarthy ◽  
C. C. Wood ◽  
P. D. Williamson ◽  
D. D. Spencer

1. The anatomic generators of human median nerve somatosensory evoked potentials (SEPs) in the 40 to 250-ms latency range were investigated in 54 patients by means of cortical-surface and transcortical recordings obtained during neurosurgery. 2. Contralateral stimulation evoked three groups of SEPs recorded from the hand representation area of sensorimotor cortex: P45-N80-P180, recorded anterior to the central sulcus (CS) and maximal on the precentral gyrus; N45-P80-N180, recorded posterior to the CS and maximal on the postcentral gyrus; and P50-N90-P190, recorded near and on either side of the CS. 3. P45-N80-P180 inverted in polarity to N45-P80-N180 across the CS but was similar in polarity from the cortical surface and white matter in transcortical recordings. These spatial distributions were similar to those of the short-latency P20-N30 and N20-P30 potentials described in the preceding paper, suggesting that these long-latency potentials are generated in area 3b of somatosensory cortex. 4. P50-N90-P190 was largest over the anterior one-half of somatosensory cortex and did not show polarity inversion across the CS. This spatial distribution was similar to that of the short-latency P25-N35 potentials described in the preceding paper and, together with our and Goldring et al. 1970; Stohr and Goldring 1969 transcortical recordings, suggest that these long-latency potentials are generated in area 1 of somatosensory cortex. 5. SEPs of apparently local origin were recorded from several regions of sensorimotor cortex to stimulation of the ipsilateral median nerve. Surface and transcortical recordings suggest that the ipsilateral potentials are generated not in area 3b, but rather in other regions of sensorimotor cortex perhaps including areas 4, 1, 2, and 7. This spatial distribution suggests that the ipsilateral potentials are generated by transcallosal input from the contralateral hemisphere. 6. Recordings from the periSylvian region were characterized by P100 and N100, recorded above and below the Sylvian sulcus (SS) respectively. This distribution suggests a tangential generator located in the upper wall of the SS in the second somatosensory area (SII). In addition, N125 and P200, recorded near and on either side of the SS, suggest a radial generator in a portion of SII located in surface cortex above the SS. 7. In comparison with the short-latency SEPs described in the preceding paper, the long-latency potentials were more variable and were more affected by intraoperative conditions.


1994 ◽  
Vol 76 (3) ◽  
pp. 1293-1301 ◽  
Author(s):  
D. R. Karius ◽  
L. Ling ◽  
D. F. Speck

This study tested the hypothesis that excitatory amino acid (EAA) neurotransmission at non-N-methyl-D-aspartate (non-NMDA), but not NMDA, receptors within medial regions of the nucleus tractus solitarius (NTS) is required in the inspiratory termination elicited by vagal or intercostal nerve (ICN) stimulation. Adult cats were anesthetized, decerebrated, vagotomized, and ventilated. After control responses to stimulation of the superior laryngeal nerve (SLN), vagus, and ICN were obtained, EAA receptor antagonists were injected into the medial aspects of the NTS. Injections of 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) or 6,7-dinitro-quinoxaline-2,3-dione (DNQX), EAA receptor antagonists; (+/-)-2-amino-5-phosphonopentanoic acid (AP5), an NMDA antagonist; or 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo(F)quinoxaline (NBQX), a non-NMDA antagonist, ipsilateral to the vagus abolished the termination response. The SLN-elicited response persisted after AP5 injection but was abolished by NBQX injections. The ICN-elicited response persisted after bilateral injections of CNQX/DNQX or procaine. We conclude that the inspiratory termination elicited by ICN stimulation is independent of the regions medial to the NTS. Inspiratory termination elicited by vagal or SLN stimulation requires non-NMDA-mediated EAA neurotransmission within medial aspects of the NTS, but the vagally elicited response also requires NMDA receptors.


1988 ◽  
Vol 65 (1) ◽  
pp. 385-392 ◽  
Author(s):  
F. Bongianni ◽  
M. Corda ◽  
G. Fontana ◽  
T. Pantaleo

The effects of superior laryngeal nerve (SLN) stimulation on the activity of the expiratory muscles and medullary expiration-related (ER) neurons were investigated in 24 pentobarbital-anesthetized cats. In some experiments the animals were also paralyzed and artificially ventilated. Sustained tetanic stimulation of SLN consistently caused an apneic response associated with the appearance of tonic CO2-dependent activity in the expiratory muscles and in ER neurons located in the caudal ventral respiratory group (VRG) and the Botzinger complex. Single shocks or brief tetani at the same stimulation intensities failed to evoke excitatory responses in the expiratory muscles and in the vast majority of ER neurons tested. At higher stimulation strengths, single shocks or short tetani elicited excitatory responses in the expiratory muscles (20- to 35-ms latency) and in the majority of ER neurons of the caudal VRG (7.5- to 15.5-ms latency). These responses were obtained only during the expiratory phase and proved to be CO2 independent. On the contrary, only inhibitory responses were evoked in the activity of Botzinger complex neurons. The observed tonic expiratory activity most likely represents a disinhibition phenomenon due to the suppression of inspiratory activity; activation of expiratory muscles at higher stimulation intensities appears to be a polysynaptic reflex mediated by ER neurons of the caudal VRG but not by Botzinger complex neurons.


Biomedicines ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 369
Author(s):  
Kaori Iimura ◽  
Nobuhiro Watanabe ◽  
Philip Milliken ◽  
Yee-Hsee Hsieh ◽  
Stephen J. Lewis ◽  
...  

Electrical stimulation of myelinated afferent fibers of the superior laryngeal nerve (SLN) facilitates calcitonin secretion from the thyroid gland in anesthetized rats. In this study, we aimed to quantify the electrical SLN stimulation-induced systemic calcitonin release in conscious rats and to then clarify effects of chronic SLN stimulation on bone mineral density (BMD) in a rat ovariectomized disease model of osteoporosis. Cuff electrodes were implanted bilaterally on SLNs and after two weeks recovery were stimulated (0.5 ms, 90 microampere) repetitively at 40 Hz for 8 min. Immunoreactive calcitonin release was initially measured and quantified in systemic venous blood plasma samples from conscious healthy rats. For chronic SLN stimulation, stimuli were applied intermittently for 3–4 weeks, starting at five weeks after ovariectomy (OVX). After the end of the stimulation period, BMD of the femur and tibia was measured. SLN stimulation increased plasma immunoreactive calcitonin concentration by 13.3 ± 17.3 pg/mL (mean ± SD). BMD in proximal metaphysis of tibia (p = 0.0324) and in distal metaphysis of femur (p = 0.0510) in chronically SLN-stimulated rats was 4–5% higher than that in sham rats. Our findings demonstrate chronic electrical stimulation of the SLNs produced enhanced calcitonin release from the thyroid gland and partially improved bone loss in OVX rats.


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.


1997 ◽  
Vol 77 (1) ◽  
pp. 522-526 ◽  
Author(s):  
C. E. Schroeder ◽  
S. Seto ◽  
P. E. Garraghty

Schroeder, C. E., S. Seto, and P. E. Garraghty. Emergence of radial nerve dominance in median nerve cortex after median nerve transection in an adult squirrel monkey. J. Neurophysiol. 77: 522–526, 1997. Throughout the glabrous representation in Area 3b, electrical stimulation of the dominant (median or ulnar) input produces robust, short-latency excitation, evident as a net extracellular “sink” in the Lamina 4 current source density (CSD) accompanied by action potentials. Stimulation of the collocated nondominant (radial nerve) input produces a subtle short-latency response in the Lamina 4 CSD unaccompanied by action potentials and followed by a clear excitatory response 12–15 ms later. Laminar response profiles for both inputs have a “feedforward” pattern, with initial activation in Lamina 4, followed by extragranular laminae. Such corepresentation of nondominant radial nerve inputs with the dominant (median or ulnar nerve) inputs in the glabrous hand surface representation provides a likely mechanism for reorganization after median nerve section in adult primates. To investigate this, we conducted repeated recordings using an implanted linear multi-electrode array straddling the cortical laminae at a site in “median nerve cortex” (i.e., at a site with a cutaneous receptive field on the volar surface of D2 and thus with its dominant afferent input conveyed by the median nerve) in an adult squirrel monkey. We characterized the baseline responses to median, radial, and ulnar nerve stimulation. We then cut the median nerve and semi-chronically monitored radial nerve, ulnar nerve and median nerve (proximal stump) evoked responses. The radial nerve response in median nerve cortex changed progressively during the weeks after median nerve transection, ultimately assuming the characteristics of the dominant nerve profile. During this time, median, and ulnar nerve profiles displayed little or no change.


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