scholarly journals Chronic assessment of diaphragm muscle EMG activity across motor behaviors

2011 ◽  
Vol 177 (2) ◽  
pp. 176-182 ◽  
Author(s):  
Carlos B. Mantilla ◽  
Yasin B. Seven ◽  
Juan N. Hurtado-Palomino ◽  
Wen-Zhi Zhan ◽  
Gary C. Sieck
Keyword(s):  
Diaphragm Muscle ◽  
Emg Activity ◽  
Motor Behaviors

scholarly journals Diaphragm muscle activity across respiratory motor behaviors in awake and lightly anesthetized rats

2018 ◽  
Vol 124 (4) ◽  
pp. 915-922 ◽  
Author(s):  
Federico Jimenez-Ruiz ◽  
Obaid U. Khurram ◽  
Wen-Zhi Zhan ◽  
Heather M. Gransee ◽  
Gary C. Sieck ◽  
...  
Keyword(s):  
Fixed Effects ◽  
Random Effect ◽  
Respiratory Muscles ◽  
Mixed Linear Model ◽  
Male Rats ◽  
Diaphragm Muscle ◽  
Emg Activity ◽  
Airway Patency ◽  
Motor Behaviors ◽  
Generating Capacity

Respiratory muscles such as the diaphragm are active across a range of behaviors including ventilation and higher-force behaviors necessary for maintenance of airway patency, and minimal information is available regarding anesthetic effects on the capacity of respiratory muscles to generate higher forces. The purpose of the present study was to determine whether diaphragm EMG activity during lower-force behaviors, such as eupnea and hypoxia-hypercapnia, is differentially affected compared with higher-force behaviors, such as a sigh, in lightly anesthetized animals. In adult male rats, chronically implanted diaphragm EMG electrodes were used to measure the effects of low-dose ketamine (30 mg/kg) and xylazine (3 mg/kg) on root mean square (RMS) EMG amplitude across a range of motor behaviors. A mixed linear model was used to evaluate the effects of ketamine-xylazine anesthesia on peak RMS EMG and ventilatory parameters, with condition (awake vs. anesthetized), behavior (eupnea, hypoxia-hypercapnia, sigh), side (left or right hemidiaphragm), and their interactions as fixed effects and animal as a random effect. Compared with the awake recordings, there was an overall reduction of peak diaphragm RMS EMG across behaviors during anesthesia, but this reduction was more pronounced during spontaneous sighs (which require ~60% of maximal diaphragm force). Respiratory rates and duty cycle during eupnea and hypoxia-hypercapnia were higher in awake compared with anesthetized conditions. These results highlight the importance of identifying anesthetic effects on a range of respiratory motor behaviors, including sighs necessary for maintaining airway patency. NEW & NOTEWORTHY Respiratory muscles accomplish a range of motor behaviors, with forces generated for ventilatory behaviors comprising only a small fraction of their maximal force generating capacity. Induction of anesthesia exerts more robust effects on the higher-force diaphragm motor behaviors such as sighs compared with eupnea. This novel information on effects of low, sedative doses of a commonly used anesthetic combination (ketamine-xylazine) highlights the importance of identifying anesthetic effects on a range of respiratory motor behaviors.

scholarly journals Diaphragm electromyographic activity following unilateral midcervical contusion injury in rats

2017 ◽  
Vol 117 (2) ◽  
pp. 545-555 ◽  
Author(s):  
Sabhya Rana ◽  
Gary C. Sieck ◽  
Carlos B. Mantilla
Keyword(s):  
Motor Units ◽  
Diaphragm Muscle ◽  
Emg Activity ◽  
High Threshold ◽  
Perineuronal Net ◽  
Neural Drive ◽  
Motor Behaviors ◽  
Neuromotor Control ◽  
Phrenic Motoneurons ◽  
Contusion Injury

Contusion-type injuries to the spinal cord are characterized by tissue loss and disruption of spinal pathways. Midcervical spinal cord injuries impair the function of respiratory muscles and may contribute to significant respiratory complications. This study systematically assessed the impact of a 100-kDy unilateral C4 contusion injury on diaphragm muscle activity across a range of motor behaviors in rats. Chronic diaphragm electromyography (EMG) was recorded before injury and at 1 and 7 days postinjury (DPI). Histological analyses assessed the extent of perineuronal net formation, white-matter sparing, and phrenic motoneuron loss. At 7 DPI, ∼45% of phrenic motoneurons were lost ipsilaterally. Relative diaphragm root mean square (RMS) EMG activity increased bilaterally across a range of motor behaviors by 7 DPI. The increase in diaphragm RMS EMG activity was associated with an increase in neural drive (RMS value at 75 ms after the onset of diaphragm activity) and was more pronounced during higher force, nonventilatory motor behaviors. Animals in the contusion group displayed a transient decrease in respiratory rate and an increase in burst duration at 1 DPI. By 7 days, following midcervical contusion, there was significant perineuronal net formation and white-matter loss that spanned 1 mm around the injury epicenter. Taken together, these findings are consistent with increased recruitment of remaining motor units, including more fatigable, high-threshold motor units, during higher force, nonventilatory behaviors. Changes in diaphragm EMG activity following midcervical contusion injury reflect complex adaptations in neuromotor control that may increase the risk of motor-unit fatigue and compromise the ability to sustain higher force diaphragm efforts. NEW & NOTEWORTHY The present study shows that unilateral contusion injury at C4 results in substantial loss of phrenic motoneurons but increased diaphragm muscle activity across a range of ventilatory and higher force, nonventilatory behaviors. Measures of neural drive indicate increased descending input to phrenic motoneurons that was more pronounced during higher force, nonventilatory behaviors. These findings reveal novel, complex adaptations in neuromotor control following injury, suggestive of increased recruitment of more fatigable, high-threshold motor units.

scholarly journals Recruitment of rat diaphragm motor units across motor behaviors with different levels of diaphragm activation

2014 ◽  
Vol 117 (11) ◽  
pp. 1308-1316 ◽  
Author(s):  
Yasin B. Seven ◽  
Carlos B. Mantilla ◽  
Gary C. Sieck
Keyword(s):  
Motor Unit ◽  
Motor Neurons ◽  
Motor Units ◽  
Motor Unit Recruitment ◽  
Diaphragm Muscle ◽  
Emg Activity ◽  
Motor Behaviors ◽  
Airway Occlusion ◽  
Recruitment Order ◽  
Central Drive

Phrenic motor neurons are recruited across a range of motor behaviors to generate varying levels of diaphragm muscle (DIAm) force. We hypothesized that DIAm motor units are recruited in a fixed order across a range of motor behaviors of varying force levels, consistent with the Henneman Size Principle. Single motor unit action potentials and compound DIAm EMG activities were recorded in anesthetized, neurally intact rats across different motor behaviors, i.e., eupnea, hypoxia-hypercapnia (10% O2 and 5% CO2), deep breaths, sustained airway occlusion, and sneezing. Central drive [estimated by root-mean-squared (RMS) EMG value 75 ms after the onset of EMG activity (RMS75)], recruitment delay, and onset discharge frequencies were similar during eupnea and hypoxia-hypercapnia. Compared with eupnea, central drive increased (∼25%) during deep breaths, and motor units were recruited ∼12 ms earlier ( P < 0.01). During airway occlusion, central drive was ∼3 times greater, motor units were recruited ∼30 ms earlier ( P < 0.01), and motor unit onset discharge frequencies were significantly higher ( P < 0.01). Recruitment order of motor unit pairs observed during eupnea was maintained for 98%, 87%, and 84% of the same pairs recorded during hypoxia-hypercapnia, deep breaths, and airway occlusion, respectively. Reversals in motor unit recruitment order were observed primarily if motor unit pairs were recruited <20 ms apart. These results are consistent with DIAm motor unit recruitment order being determined primarily by the intrinsic size-dependent electrophysiological properties of phrenic motor neurons.

scholarly journals BDNF effects on functional recovery across motor behaviors after cervical spinal cord injury

2017 ◽  
Vol 117 (2) ◽  
pp. 537-544 ◽  
Author(s):  
Vivian Hernandez-Torres ◽  
Heather M. Gransee ◽  
Carlos B. Mantilla ◽  
Yao Wang ◽  
Wen-Zhi Zhan ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Motor Neurons ◽  
Neurotrophic Factor ◽  
Cervical Spinal Cord ◽  
Brain Derived Neurotrophic Factor ◽  
Diaphragm Muscle ◽  
Emg Activity ◽  
Motor Behaviors ◽  
Airway Occlusion ◽  
Spinal Cord Hemisection

Unilateral C2 cervical spinal cord hemisection (SH) disrupts descending excitatory drive to phrenic motor neurons, thereby paralyzing the ipsilateral diaphragm muscle (DIAm) during ventilatory behaviors. Recovery of rhythmic DIAm activity ipsilateral to injury occurs over time, consistent with neuroplasticity and strengthening of spared synaptic inputs to phrenic motor neurons. Localized intrathecal delivery of brain-derived neurotrophic factor (BDNF) to phrenic motor neurons after SH enhances recovery of eupneic DIAm activity. However, the impact of SH and BDNF treatment on the full range of DIAm motor behaviors has not been fully characterized. We hypothesized that all DIAm motor behaviors are affected by SH and that intrathecal BDNF enhances the recovery of both ventilatory and higher force, nonventilatory motor behaviors. An intrathecal catheter was placed in adult, male Sprague-Dawley rats at C4 to chronically infuse artificial cerebrospinal fluid (aCSF) or BDNF. DIAm electromyography (EMG) electrodes were implanted bilaterally to record activity across motor behaviors, i.e., eupnea, hypoxia-hypercapnia (10% O2 and 5% CO2), sighs, airway occlusion, and sneezing. After SH, ipsilateral DIAm EMG activity was evident in only 43% of aCSF-treated rats during eupnea, and activity was restored in all rats after BDNF treatment. The amplitude of DIAm EMG (root mean square, RMS) was reduced following SH during eupnea and hypoxia-hypercapnia in aCSF-treated rats, and BDNF treatment promoted recovery in both conditions. The amplitude of DIAm RMS EMG during sighs, airway occlusion, and sneezing was not affected by SH or BDNF treatment. We conclude that the effects of SH and BDNF treatment on DIAm activity depend on motor behavior. NEW & NOTEWORTHY This study demonstrates that after unilateral C2 spinal cord hemisection (SH), there are differences in the spontaneous recovery of diaphragm (DIAm) electromyographic activity during ventilatory compared with more forceful, nonventilatory motor behaviors. Furthermore, we show that intrathecal delivery of brain-derived neurotrophic factor (BDNF) at the level of the phrenic motor neuron pool enhances recovery of ipsilateral DIAm activity following SH, exerting main effects on recovery of ventilatory but not higher force, nonventilatory behaviors.

scholarly journals Diaphragm muscle function following midcervical contusion injury in rats

2019 ◽  
Vol 126 (1) ◽  
pp. 221-230 ◽  
Author(s):  
Obaid U. Khurram ◽  
Matthew J. Fogarty ◽  
Sabhya Rana ◽  
Pangdra Vang ◽  
Gary C. Sieck ◽  
...  
Keyword(s):  
Motor Neuron ◽  
Motor Neurons ◽  
Force Generation ◽  
Diaphragm Muscle ◽  
Neuron Loss ◽  
Motor Behaviors ◽  
Contusion Injury ◽  
Motor Neuron Loss ◽  
The Impact ◽  
Over Time

Midcervical spinal cord contusion injury results in tissue damage, disruption of spinal pathways, and motor neuron loss. Unilateral C4 contusion results in loss of 40%–50% of phrenic motor neurons ipsilateral to the injury (~25% of the total phrenic motor neuron pool). Over time after unilateral C4 contusion injury, diaphragm muscle (DIAm) electromyogram activity increases both contralateral and ipsilateral to the side of injury in rats, suggesting compensation because of increased activation of the surviving motor neurons. However, the impact of contusion injury on DIAm force generation is less clear. Transdiaphragmatic pressure (Pdi) was measured across motor behaviors over time after unilateral C4 contusion injury in adult male Sprague-Dawley rats. Maximum Pdi (Pdimax) was elicited by bilateral phrenic nerve stimulation at 7 days postinjury. We hypothesized that Pdimax is reduced following unilateral C4 contusion injury, whereas ventilatory behaviors of the DIAm are unimpaired. In support of our hypothesis, Pdimax was reduced by ~25% after unilateral C4 contusion, consistent with the extent of phrenic motor neuron loss following contusion injury. One day after contusion injury, the Pdi amplitude during airway occlusion was reduced from ~30 to ~20 cmH2O, but this reduction was completely reversed by 7 days postinjury. Ventilatory behaviors (~10 cmH2O), DIAm-specific force, and muscle fiber cross-sectional area did not differ between the laminectomy and contusion groups. These results indicate that the large reserve capacity for DIAm force generation allows for higher-force motor behaviors to be accomplished despite motor neuron loss, likely reflecting changes in motor unit recruitment. NEW & NOTEWORTHY Respiratory muscles such as the diaphragm generate the pressures necessary to accomplish a variety of motor behaviors ranging from ventilation to near-maximal expulsive behaviors. However, the impact of contusion injury on diaphragm pressure generation across behaviors is not clear. The present study shows that contusion injury impairs maximal pressure generation while preserving the ability of the diaphragm to accomplish lower-force motor behaviors, likely reflecting changes in diaphragm motor unit recruitment.

scholarly journals Prolonged C2 spinal hemisection-induced inactivity reduces diaphragm muscle specific force with modest, selective atrophy of type IIx and/or IIb fibers

2013 ◽  
Vol 114 (3) ◽  
pp. 380-386 ◽  
Author(s):  
Carlos B. Mantilla ◽  
Sarah M. Greising ◽  
Wen-Zhi Zhan ◽  
Yasin B. Seven ◽  
Gary C. Sieck
Keyword(s):  
Spinal Cord ◽  
Muscle Fiber ◽  
Fiber Type ◽  
Diaphragm Muscle ◽  
Emg Activity ◽  
Type I ◽  
Specific Force ◽  
Type Distribution ◽  
Fiber Size ◽  
Fiber Type Distribution

The diaphragm muscle (DIAm) is critically responsible for sustaining ventilation. Previously we showed in a commonly used model of spinal cord injury, unilateral spinal cord hemisection at C2 (SH), that there are minimal changes to muscle fiber cross-sectional area (CSA) and fiber type distribution following 14 days of SH-induced ipsilateral DIAm inactivity. In the present study, effects of long-term SH-induced inactivity on DIAm fiber size and force were examined. We hypothesized that prolonged inactivity would not result in substantial DIAm atrophy or force loss. Adult rats were randomized to control or SH groups ( n = 34 total). Chronic bilateral DIAm electromyographic (EMG) activity was monitored during resting breathing. Minimal levels of spontaneous recovery of ipsilateral DIAm EMG activity were evident in 42% of SH rats (<25% of preinjury root mean square amplitude). Following 42 days of SH, DIAm specific force was reduced 39%. There was no difference in CSA for type I or IIa DIAm fibers in SH rats compared with age, weight-matched controls (classification based on myosin heavy chain isoform expression). Type IIx and/or IIb DIAm fibers displayed a modest 20% reduction in CSA ( P < 0.05). Overall, there were no differences in the distribution of fiber types or the contribution of each fiber type to the total DIAm CSA. These data indicate that reduced specific force following prolonged inactivity of the DIAm is associated with modest, fiber type selective adaptations in muscle fiber size and fiber type distribution.

scholarly journals Key aspects of phrenic motoneuron and diaphragm muscle development during the perinatal period

2008 ◽  
Vol 104 (6) ◽  
pp. 1818-1827 ◽  
Author(s):  
Carlos B. Mantilla ◽  
Gary C. Sieck
Keyword(s):  
Muscle Development ◽  
Respiratory Muscles ◽  
Motor Units ◽  
Perinatal Period ◽  
Diaphragm Muscle ◽  
Postnatal Maturation ◽  
Motor Behaviors ◽  
Phrenic Motoneurons ◽  
Phrenic Motoneuron ◽  
Key Aspects

At the time of birth, respiratory muscles must be activated to sustain ventilation. The perinatal development of respiratory motor units (comprising an individual motoneuron and the muscle fibers it innervates) shows remarkable features that enable mammals to transition from in utero conditions to the air environment in which the remainder of their life will occur. In addition, significant postnatal maturation is necessary to provide for the range of motor behaviors necessary during breathing, swallowing, and speech. As the main inspiratory muscle, the diaphragm muscle (and the phrenic motoneurons that innervate it) plays a key role in accomplishing these behaviors. Considerable diversity exists across diaphragm motor units, but the determinant factors for this diversity are unknown. In recent years, the mechanisms underlying the development of respiratory motor units have received great attention, and this knowledge may provide the opportunity to design appropriate interventions for the treatment of respiratory disease not only in the perinatal period but likely also in the adult.

Effects of intraphrenic injection of potassium on diaphragm activation

1993 ◽  
Vol 74 (3) ◽  
pp. 1186-1194 ◽  
Author(s):  
G. S. Supinski ◽  
T. Dick ◽  
D. Stofan ◽  
A. F. DiMarco
Keyword(s):  
Arterial Pressure ◽  
Systemic Arterial Pressure ◽  
Diaphragm Muscle ◽  
Emg Activity ◽  
Inferior Phrenic Artery ◽  
Excitatory Response ◽  
Integrated Emg ◽  
Phrenic Artery ◽  
Sustained Increase

The purpose of the present study was to determine whether potassium, injected into the arterial supply of the diaphragm, would reflexly alter efferent diaphragmatic motor outflow and systemic arterial pressure. Studies were performed using in situ canine diaphragm muscle strips in which the inferior phrenic artery and vein were cannulated and all other sources of strip blood flow were ligated. Injection of potassium (0.1 meq) into the inferior phrenic artery elicited a small transient (1–2 breaths) decrease in the peak strip tension developed during spontaneous muscle contractions, in peak integrated strip electromyographic (EMG) activity, and in the peak integrated EMG activity of the contralateral hemidiaphragm. This was followed by a more pronounced and more sustained increase in each of these parameters as well as an increase in systemic arterial pressure. This latter excitatory response was qualitatively similar to that induced by the injection of capsaicin (5 and 25 micrograms) into the phrenic artery. Section of the left phrenic nerve abolished the effects of intra-arterial potassium and capsaicin on systemic arterial pressure and right hemidiaphragm EMG activity. These data support the existence of a potent excitatory phrenic-to-phrenic reflex that can be activated by potassium injection into the diaphragm. Activation of this pathway increases diaphragm motor activation and augments systemic arterial pressure.

scholarly journals Predicting the activation states of the muscles governing upper esophageal sphincter relaxation and opening

2016 ◽  
Vol 310 (6) ◽  
pp. G359-G366 ◽  
Author(s):  
Taher I. Omari ◽  
Corinne A. Jones ◽  
Michael J. Hammer ◽  
Charles Cock ◽  
Philip Dinning ◽  
...  
Keyword(s):  
Sensory Information ◽  
Upper Esophageal Sphincter ◽  
Intraluminal Pressure ◽  
Emg Activity ◽  
Motor Behaviors ◽  
Pharyngeal Pressure ◽  
Intraluminal Impedance ◽  
Esophageal Sphincter ◽  
Ues Opening ◽  
Swallowing Muscles

The swallowing muscles that influence upper esophageal sphincter (UES) opening are centrally controlled and modulated by sensory information. Activation and deactivation of neural inputs to these muscles, including the intrinsic cricopharyngeus (CP) and extrinsic submental (SM) muscles, results in their mechanical activation or deactivation, which changes the diameter of the lumen, alters the intraluminal pressure, and ultimately reduces or promotes flow of content. By measuring the changes in diameter, using intraluminal impedance, and the concurrent changes in intraluminal pressure, it is possible to determine when the muscles are passively or actively relaxing or contracting. From these “mechanical states” of the muscle, the neural inputs driving the specific motor behaviors of the UES can be inferred. In this study we compared predictions of UES mechanical states directly with the activity measured by electromyography (EMG). In eight subjects, pharyngeal pressure and impedance were recorded in parallel with CP- and SM-EMG activity. UES pressure and impedance swallow profiles correlated with the CP-EMG and SM-EMG recordings, respectively. Eight UES muscle states were determined by using the gradient of pressure and impedance with respect to time. Guided by the level and gradient change of EMG activity, mechanical states successfully predicted the activity of the CP muscle and SM muscle independently. Mechanical state predictions revealed patterns consistent with the known neural inputs activating the different muscles during swallowing. Derivation of “activation state” maps may allow better physiological and pathophysiological interpretations of UES function.

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