Effect of upper airway negative pressure and lung inflation on laryngeal motor unit activity in rabbit

2002 ◽  
Vol 92 (1) ◽  
pp. 269-278 ◽  
Author(s):  
Stephen Ryan ◽  
Walter T. McNicholas ◽  
Ronan G. O'Regan ◽  
Philip Nolan
Keyword(s):  
Recurrent Laryngeal Nerve ◽  
Motor Unit ◽  
Unit Activity ◽  
Negative Pressure ◽  
Upper Airway ◽  
Motor Units ◽  
Laryngeal Nerve ◽  
Lung Inflation ◽  
Inspiratory Activity ◽  
Vagal Bradycardia

10.1152/japplphysiol.00413.2001.—Distortion of the upper airway by negative transmural pressure (UANP) causes reflex vagal bradycardia. This requires activation of cardiac vagal preganglionic neurons, which exhibit postinspiratory (PI) discharge. We hypothesized that UANP would also stimulate cranial respiratory motoneurons with PI activity. We recorded 32 respiratory modulated motor units from the recurrent laryngeal nerve of seven decerebrate paralyzed rabbits and recorded their responses to UANP and to withholding lung inflation using a phrenic-triggered ventilator. The phasic inspiratory ( n = 17) and PI ( n = 5) neurons detected were stimulated by −10 cmH2O UANP and by withdrawal of lung inflation ( P < 0.05, Friedman's ANOVA). Expiratory-inspiratory units ( n = 10) were tonically active but transiently inhibited in postinspiration; this inhibition was more pronounced and prolonged during UANP stimuli and during no-inflation tests ( P < 0.05). We conclude that, in addition to increasing inspiratory activity in the recurrent laryngeal nerve, UANP also stimulates units with PI activity.

Nasal and laryngeal reflex responses to negative upper airway pressure

1984 ◽  
Vol 56 (3) ◽  
pp. 746-752 ◽  
Author(s):  
E. van Lunteren ◽  
W. B. Van de Graaff ◽  
D. M. Parker ◽  
J. Mitra ◽  
M. A. Haxhiu ◽  
...  
Keyword(s):  
Negative Pressure ◽  
Muscle Activity ◽  
Moving Average ◽  
Superior Laryngeal Nerve ◽  
Upper Airway ◽  
Laryngeal Nerve ◽  
Topical Anesthesia ◽  
Inspiratory Activity ◽  
Posterior Cricoarytenoid ◽  
Upper Airway Muscles

The effects of negative pressure applied to just the upper airway on nasal and laryngeal muscle activity were studied in 14 spontaneously breathing anesthetized dogs. Moving average electromyograms were recorded from the alae nasi (AN) and posterior cricoarytenoid (PCA) muscles and compared with those of the genioglossus (GG) and diaphragm. The duration of inspiration and the length of inspiratory activity of all upper airway muscles was increased in a graded manner proportional to the amount of negative pressure applied. Phasic activation of upper airway muscles preceded inspiratory activity of the diaphragm under control conditions; upper airway negative pressure increased this amount of preactivation. Peak diaphragm activity was unchanged with negative pressure, although the rate of rise of muscle activity decreased. The average increases in peak upper airway muscle activity in response to all levels of negative pressure were 18 +/- 4% for the AN, 27 +/- 7% for the PCA, and 122 +/- 31% for the GG (P less than 0.001). Rates of rise of AN and PCA electrical activity increased at higher levels of negative pressure. Nasal negative pressure affected the AN more than the PCA, while laryngeal negative pressure had the opposite effect. The effects of nasal negative pressure could be abolished by topical anesthesia of the nasal passages, while the effects of laryngeal negative pressure could be abolished by either topical anesthesia of the larynx or section of the superior laryngeal nerve. Electrical stimulation of the superior laryngeal nerve caused depression of AN and PCA activity, and hence does not reproduce the effects of negative pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Upper airway pressure receptors alter expiratory muscle EMG and motor unit firing

1988 ◽  
Vol 65 (1) ◽  
pp. 210-217 ◽  
Author(s):  
E. van Lunteren ◽  
N. S. Cherniack ◽  
T. E. Dick
Keyword(s):  
Motor Unit ◽  
Unit Activity ◽  
Upper Airway ◽  
Motor Units ◽  
Firing Frequency ◽  
Single Motor Unit ◽  
Expiratory Muscle ◽  
Motor Unit Activity ◽  
Motor Unit Firing ◽  
Respiratory Muscle Activity

To examine the effects of upper airway negative pressure (UAW NP) afferents on respiratory muscle activity during expiration (TE), diaphragm electromyograms (EMG) and triangularis sterni EMG and single motor unit activity were recorded from supine anesthetized tracheotomized cats while they breathed 100% O2. The period of TE during which the diaphragm was electrically active (TE-1) and the period of TE during which the diaphragm was quiescent (TE-2) were both increased with continuous UAW NP (P less than 0.001 and P less than 0.05, respectively), as was TE-1 as a percent of TE (P less than 0.001). Continuous UAW NP reduced peak triangularis sterni EMG (P less than 0.001) and delayed its expiratory onset (P less than 0.005) but did not alter its duration of firing. Changes in triangularis sterni EMG were due to a combination of complete cessation of motor unit activity (2 of 17 motor units), a reduction in mean motor unit firing frequency (P less than 0.02), and a delay in the expiratory onset of motor unit activity (P less than 0.001). Qualitatively similar results were obtained when UAW NP was applied during inspiration only. We conclude that 1) UAW NP has reciprocal stimulatory and inhibitory influences on diaphragm and triangularis sterni muscle electrical activity, respectively, during expiration, and 2) the reductions in triangularis sterni EMG are due to both motor unit derecruitment and a slowing of motor unit firing frequency.

scholarly journals Genioglossus motor unit activity in supine and upright postures in obstructive sleep apnea

SLEEP ◽  
2019 ◽  
Vol 43 (6) ◽  
Author(s):  
Billy L Luu ◽  
Julian P Saboisky ◽  
Rachel A McBain ◽  
John A Trinder ◽  
David P White ◽  
...  
Keyword(s):  
Obstructive Sleep Apnea ◽  
Sleep Apnea ◽  
Motor Unit ◽  
Unit Activity ◽  
Upper Airway ◽  
Motor Units ◽  
Healthy Controls ◽  
Quiet Breathing ◽  
Supine Posture ◽  
Obstructive Sleep

Abstract This study investigated whether a change in posture affected the activity of the upper-airway dilator muscle genioglossus in participants with and without obstructive sleep apnea (OSA). During wakefulness, a monopolar needle electrode was used to record single motor unit activity in genioglossus in supine and upright positions to alter the gravitational load that causes narrowing of the upper airway. Activity from 472 motor units was recorded during quiet breathing in 17 males, nine of whom had OSA. The mean number of motor units for each participant was 11.8 (SD 3.4) in the upright and 16.0 (SD 4.2) in the supine posture. For respiratory-modulated motor units, there were no significant differences in discharge frequencies between healthy controls and participants with OSA. Within each breath, genioglossus activity increased through the recruitment of phasic motor units and an increase in firing rate, with an overall increase of ~6 Hz (50%) across both postures and participant groups. However, the supine posture did not lead to compensatory increases in the peak discharge frequencies of inspiratory and expiratory motor units, despite the increase in gravitational load on the upper airway. Posture also had no significant effect on the discharge frequency of motor units that showed no respiratory modulation during quiet breathing. We postulate that, in wakefulness, any increase in genioglossus activity to compensate for the gravitational effects on the upper airway is achieved primarily through the recruitment of additional motor units in both healthy controls and participants with OSA.

Effect of hypoxia on abdominal motor unit activities in spontaneously breathing cats

1996 ◽  
Vol 81 (6) ◽  
pp. 2428-2435 ◽  
Author(s):  
J. H. Mateika ◽  
E. Essif ◽  
R. F. Fregosi
Keyword(s):  
Motor Unit ◽  
Unit Activity ◽  
Motor Units ◽  
Discharge Frequency ◽  
Oblique Muscle ◽  
Single Motor Unit ◽  
Motor Unit Activity ◽  
Rate Coding ◽  
External Oblique ◽  
Spontaneously Breathing

Mateika, J. H., E. Essif, and R. F. Fregosi. Effect of hypoxia on abdominal motor unit activities in spontaneously breathing cats. J. Appl. Physiol. 81(6): 2428–2435, 1996.—These experiments were designed to examine the behavior of external oblique motor units in spontaneously breathing cats during hypoxia and to estimate the contribution of recruitment and rate coding to changes in the integrated external oblique electromyogram (iEMG). Motor unit activities in the external oblique muscle were identified while the cats expired against a positive end-expiratory pressure (PEEP) of 1–2.5 cmH2O. After localization of unit activity, PEEP was removed, and recordings were made continuously for 3–4 min during hyperoxia, normoxia, and hypoxia. A total of 35 single motor unit activities were recorded from 10 cats. At each level of fractional concentration of end-tidal O2, the motor unit activity was characterized by an abrupt increase in mean discharge frequency, at ∼30% of expiratory time, which then continued to increase gradually or remained constant before declining abruptly at the end of expiration. The transition from hyperoxia to normoxia and hypoxia was accompanied by an increase in the number of active motor units (16 of 35, 20 of 35, and 29 of 35, respectively) and by an increase in the mean discharge frequency of those units active during hyperoxia. The changes in motor unit activity recorded during hypoxia were accompanied by a significant increase in the average peak amplitude of the abdominal iEMG. Linear regression analysis revealed that motor unit rate coding was responsible for close to 60% of the increase in peak iEMG amplitude. The changes in abdominal motor unit activity and the external oblique iEMG that occurred during hypoxia were abolished if the arterial [Formula: see text] was allowed to fall. We conclude that external oblique motor units are activated during the latter two-thirds of expiration and that rate coding and recruitment contribute almost equally to the increase in expiratory muscle activity that occurs with hypoxia. In addition, the excitation of abdominal motor units during hypoxia is critically dependent on changes in CO2 and/or tidal volume.

scholarly journals Effect of upper airway negative pressure on inspiratory drive during sleep

1998 ◽  
Vol 84 (3) ◽  
pp. 1063-1075 ◽  
Author(s):  
P. R. Eastwood ◽  
A. K. Curran ◽  
C. A. Smith ◽  
J. A. Dempsey
Keyword(s):  
Eye Movement ◽  
Rem Sleep ◽  
Negative Pressure ◽  
Upper Airway ◽  
Resistive Load ◽  
Rapid Eye Movement ◽  
Inhibitory Effects ◽  
Lung Inflation ◽  
Tracheal Occlusion ◽  
Tracheal Pressure

To determine the effect of upper airway (UA) negative pressure and collapse during inspiration on regulation of breathing, we studied four unanesthetized female dogs during wakefulness and sleep while they breathed via a fenestrated tracheostomy tube, which was sealed around the permanent tracheal stoma. The snout was sealed with an airtight mask, thereby isolating the UA when the fenestration (Fen) was closed and exposing the UA to intrathoracic pressure changes, but not to flow changes, when Fen was open. During tracheal occlusion with Fen closed, inspiratory time (Ti) increased during wakefulness, non-rapid-eye-movement (NREM) sleep and rapid-eye-movement (REM) sleep (155 ± 8, 164 ± 11, and 161 ± 32%, respectively), reflecting the removal of inhibitory lung inflation reflexes. During tracheal occlusion with Fen open (vs. Fen closed): 1) the UA remained patent; 2) Ti further increased during wakefulness and NREM (215 ± 52 and 197 ± 28%, respectively) but nonsignificantly during REM sleep (196 ± 42%); 3) mean rate of rise of diaphragm EMG (EMGdi/Ti) and rate of fall of tracheal pressure (Ptr/Ti) were decreased, reflecting an additional inhibitory input from UA receptors; and 4) both EMGdi/Ti and Ptr/Ti were decreased proportionately more as inspiration proceeded, suggesting greater reflex inhibition later in the effort. Similar inhibitory effects of exposing the UA to negative pressure (via an open tracheal Fen) were seen when an inspiratory resistive load was applied over several breaths during wakefulness and sleep. These inhibitory effects persisted even in the face of rising chemical stimuli. This inhibition of inspiratory motor output is alinear within an inspiration and reflects the activation of UA pressure-sensitive receptors by UA distortion, with greater distortion possibly occurring later in the effort.

Effects of Recurrent Laryngeal Nerve Transection and Vagotomy on Respiratory Contraction of the Cricothyroid Muscle

1989 ◽  
Vol 98 (5) ◽  
pp. 373-378 ◽  
Author(s):  
Gayle E. Woodson
Keyword(s):  
Recurrent Laryngeal Nerve ◽  
Superior Laryngeal Nerve ◽  
Upper Airway ◽  
Vocal Folds ◽  
Laryngeal Nerve ◽  
Electromyographic Activity ◽  
Airway Occlusion ◽  
Cricothyroid Muscle ◽  
Bilateral Vagotomy ◽  
Posterior Cricoarytenoid

The cricothyroid muscle (CT) appears to be an accessory muscle of respiration. Phasic inspiratory contraction is stimulated by increasing respiratory demand. Reflex activation of the CT may be responsible for the paramedian position of the vocal folds, and hence airway obstruction, in patients with bilateral recurrent laryngeal nerve (RLN) paralysis. Previous research has demonstrated the influence of superior laryngeal nerve (SLN) afferents on CT activity. The present study addresses the effects of vagal and RLN afferents. Electromyographic activity of the CT and right posterior cricoarytenoid muscle was monitored in anesthetized cats during tracheotomy breathing and in response to tracheal or upper airway occlusion in the intact animal. This was repeated following left RLN transection, bilateral vagotomy, and bilateral SLN transection. Vagotomy abolished CT response to tracheal occlusion and markedly reduced the response to upper airway occlusion. Vocal fold position following RLN transection appeared to correlate with CT activity; however, observed changes were minor.

Interactive effects of CO2 and upper airway negative pressure on breathing pattern

1987 ◽  
Vol 63 (1) ◽  
pp. 229-237 ◽  
Author(s):  
E. van Lunteren
Keyword(s):  
Tidal Volume ◽  
Respiratory Rate ◽  
Negative Pressure ◽  
Upper Airway ◽  
Interactive Effects ◽  
Inspiratory Time ◽  
Diaphragm Electrical Activity ◽  
Wide Range ◽  
Inspiratory Activity ◽  
The Relationship

The interactive effects of upper airway negative pressure and hypercapnia on the pattern of breathing were assessed in pentobarbital-anesthetized cats. At any given level of pressure in the upper airway, hypercapnia increased respiratory rate, reduced inspiratory time, and augmented tidal volume, inspiratory airflow, and the peak and rate of rise of diaphragm electrical activity. Conversely, at any given level of CO2, upper airway negative pressure decreased respiratory rate, prolonged inspiratory time, and depressed inspiratory airflow and diaphragm electromyogram (EMG) rate of rise. Application of negative pressure to the upper airway shifted the relationship between tidal volume and inspiratory time upward and rightward. The relationship between inspiratory and expiratory times, however, was linearly correlated over a wide range of chemical drives and levels of upper airway pressure. These results suggest that in the anesthetized cat upper airway negative pressure afferent inputs 1) interact in an additive fashion with hypercapnia to alter the pattern of breathing, 2) interact multiplicatively with CO2 to influence mean inspiratory airflow and diaphragm EMG rate of rise, 3) depress the generation of central inspiratory activity, 4) increase the time-dependent volume threshold for inspiratory termination, and 5) affect the ratio between inspiratory and expiratory times in a similar manner as alterations in PCO2.

scholarly journals Motor unit activity in biceps brachii of left-handed humans during sustained contractions with two load types

2016 ◽  
Vol 116 (3) ◽  
pp. 1358-1365 ◽  
Author(s):  
Jeffrey R. Gould ◽  
Brice T. Cleland ◽  
Diba Mani ◽  
Ioannis G. Amiridis ◽  
Roger M. Enoka
Keyword(s):  
Motor Unit ◽  
Unit Activity ◽  
Position Control ◽  
Biceps Brachii ◽  
Motor Units ◽  
Motor Unit Activity ◽  
Time Interaction ◽  
Left Handed ◽  
Position Task ◽  
Task Time

The purpose of the study was to compare the discharge characteristics of single motor units during sustained isometric contractions that required either force or position control in left-handed individuals. The target force for the two sustained contractions (24.9 ± 10.5% maximal force) was identical for each biceps brachii motor unit ( n = 32) and set at 4.7 ± 2.0% of maximal voluntary contraction (MVC) force above its recruitment threshold (range: 0.5–41.2% MVC force). The contractions were not sustained to task failure, but the duration (range: 60–330 s) was identical for each motor unit and the decline in MVC force immediately after the sustained contractions was similar for the two tasks (force: 11.1% ± 13.7%; position: 11.6% ± 9.9%). Despite a greater increase in the rating of perceived exertion during the position task (task × time interaction, P < 0.006), the amplitude of the surface-recorded electromyogram for the agonist and antagonist muscles increased similarly during the two tasks. Nonetheless, mean discharge rate of the biceps brachii motor units declined more during the position task (task × time interaction, P < 0.01) and the variability in discharge times (coefficient of variation for interspike interval) increased only during the position task (task × time interaction, P < 0.008). When combined with the results of an identical study on right-handers (Mottram CJ, Jakobi JM, Semmler JG, Enoka RM. J Neurophysiol 93: 1381–1392, 2005), the findings indicate that handedness does not influence the adjustments in biceps brachii motor unit activity during sustained submaximal contractions requiring either force or position control.

An integrative model of motor unit activity during sustained submaximal contractions

2010 ◽  
Vol 108 (6) ◽  
pp. 1550-1562 ◽  
Author(s):  
Jakob L. Dideriksen ◽  
Dario Farina ◽  
Martin Baekgaard ◽  
Roger M. Enoka
Keyword(s):  
Motor Unit ◽  
Unit Activity ◽  
Discharge Rate ◽  
Motor Units ◽  
Compartment Model ◽  
Integrative Model ◽  
Motor Unit Activity ◽  
Discharge Rates ◽  
Motor Unit Discharge ◽  
Experimental Findings

The purpose of the study was to expand a model of motor unit recruitment and rate coding ( 30 ) to simulate the adjustments that occur during a fatiguing contraction. The major new components of the model were the introduction of time-varying parameters for motor unit twitch force, recruitment, discharge rate, and discharge variability, and a control algorithm that estimates the net excitation needed by the motoneuron pool to maintain a prescribed target force. The fatigue-induced changes in motor unit activity in the expanded model are a function of changes in the metabolite concentrations that were computed with a compartment model of the intra- and extracellular spaces. The model was validated by comparing the simulation results with data available from the literature and experimentally recorded in the present study during isometric contractions of the first dorsal interosseus muscle. The output of the model was able to replicate a number of experimental findings, including the time to task failure for a range of target forces, the changes in motor unit discharge rates, the skewness and kurtosis of the interspike interval distributions, discharge variability, and the discharge characteristics of newly recruited motor units. The model output provides an integrative perspective of the adjustments during fatiguing contractions that are difficult to measure experimentally.

scholarly journals Preparatory activity links frontal eye field activity with small amplitude motor unit recruitment of neck muscles during gaze planning

2021 ◽  
Author(s):  
Satya P. Rungta ◽  
Debaleena Basu ◽  
Naveen Sendhilnathan ◽  
Aditya Murthy
Keyword(s):  
Motor Unit ◽  
Eye Movement ◽  
Unit Activity ◽  
Small Amplitude ◽  
Motor Units ◽  
Delay Period ◽  
Neck Muscles ◽  
Frontal Eye Field ◽  
Motor Unit Activity ◽  
Eye Field

AbstractA hallmark of intelligent behavior is that we can separate intention from action. To understand the mechanism that gates the flow of information between motor planning and execution, we compared the activity of frontal eye field neurons with motor unit activity from neck muscles in the presence of an intervening delay period in which spatial information regarding the target was available to plan a response. Whereas we could infer spatially-specific delayed period activity from the activity of frontal eye field neurons, neck motor unit activity during the delay period could not be used to infer the direction of an upcoming movement, Nonetheless, motor unit activity was correlated with the time it took to initiate saccades. Interestingly, we observed a heterogeneity of responses amongst motor units, such that only units with smaller amplitudes showed a clear modulation during the delay period. These small amplitude motor units also had higher spontaneous activity compared to the units which showed modulation only during the movement epoch. Taken together, our results suggest that the temporal information is visible in the periphery amongst smaller motor units during eye movement planning and explains how the delay period primes muscle activity leading to faster reaction times.Significance statementThis study shows that the temporal aspects of a motor plan in the oculomotor circuitry can be accessed by peripheral neck muscles hundreds of milliseconds prior to the instruction to initiate a saccadic eye movement. The coupling between central and peripheral processes during the delay time is mediated by the recruitment pattern of motor units with smaller amplitude in the periphery. Besides giving insight into how information processed in cortical areas is read out by the muscles, these findings could be useful to decode intentional signals from the periphery to control brain machine interface devices.

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