Role of support afferentation in control of the tonic muscle activity

1. The expiratory role of the segmental, respiratory dorso-ventral muscles, and the inspiratory role of the subintestinal muscle, have been confirmed using intact preparations of aeshnid dragonfly larvae. 2. The strain developed by individual respiratory dorso-ventral muscles has been measured. 3. The respiratory dorso-ventral muscles all cease firing simultaneously, about 100 msec before the sterna are fully raised, and do not have any mechanical effect on the sterna after this time. It is suggested that the delay is caused either because the role of these muscles is to lift the sterna past some critical position, and/or because of the inertia of the expiratory current. 4. Periodically the sterna are raised and then lowered slowly in a series of steps, each pause in the lowering coinciding with activity in the respiratory dorso-ventral muscles. This form of ventilation is compared with others previously described. 5. In normal ventilation, and in other types of ventilation, activity in the respiratory dorso-ventral muscles shows a pronounced tendency to begin in the most posterior segments and to continue for longer periods in those segments. 6. Some aspects of the central neural connexions involved in normal ventilation are discussed.

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Kinematic and Electromyographic Analysis of the functional role of the body axis during Terrestrial and Aquatic Locomotion in the Salamander Ambystoma Tigrinum

Journal of Experimental Biology ◽

10.1242/jeb.162.1.107 ◽

1992 ◽

Vol 162 (1) ◽

pp. 107-130 ◽

Cited By ~ 10

Author(s):

LARRY M. FROLICH ◽

ANDREW A. BIEWENER

Keyword(s):

Muscle Activity ◽

Functional Role ◽

The Body ◽

Ambystoma Tigrinum ◽

Terrestrial Locomotion ◽

Aquatic Locomotion ◽

Wave Patterns ◽

Axial Morphology ◽

Electromyographic Analysis

Aquatic neotenic and terrestrial metamorphosed salamanders {Ambystoma tigrinum) were videotaped simultaneously with electromyographic (EMG) recording from five epaxial myotomes along the animal's trunk during swimming in a flow tank and trotting on a treadmill to investigate axial function during aquatic and terrestrial locomotion. Neotenic and metamorphosed individuals swim using very similar axial wave patterns, despite significant differences in axial morphology. During swimming, both forms exhibit traveling waves of axial flexion and muscle activity, with an increasing EMG-mechanical delay as these waves travel down the trunk. In contrast to swimming, during trotting metamorphosed individuals exhibit a standing wave of axial flexion produced by synchronous activation of ipsilateral epaxial myotomes along the trunk. Thus, metamorphosed individuals employ two distinct axial motor programs -- one used during swimming and one used during trotting. The transition from a traveling axial wave during swimming to a standing axial wave during trotting in A. tigrinum may be an appropriate analogy for similar transitions in axial locomotor function during theoriginal evolution of terrestriality in early tetrapods.

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Mechanics of the fast-start: muscle function and the role of intramuscular pressure in the escape behavior of amia calva and polypterus palmas

Journal of Experimental Biology ◽

10.1242/jeb.201.22.3041 ◽

1998 ◽

Vol 201 (22) ◽

pp. 3041-3055 ◽

Cited By ~ 14

Author(s):

MW Westneat ◽

ME Hale ◽

MJ Mchenry ◽

JH Long

Keyword(s):

Muscle Activity ◽

Escape Response ◽

Muscle Force ◽

Escape Behavior ◽

Pressure Change ◽

The Body ◽

Intramuscular Pressure ◽

Fast Start ◽

Amia Calva

The fast-start escape response is a rapid, powerful body motion used to generate high accelerations of the body in virtually all fishes. Although the neurobiology and behavior of the fast-start are often studied, the patterns of muscle activity and muscle force production during escape are less well understood. We studied the fast-starts of two basal actinopterygian fishes (Amia calva and Polypterus palmas) to investigate the functional morphology of the fast-start and the role of intramuscular pressure (IMP) in escape behavior. Our goals were to determine whether IMP increases during fast starts, to look for associations between muscle activity and elevated IMP, and to determine the functional role of IMP in the mechanics of the escape response. We simultaneously recorded the kinematics, muscle activity patterns and IMP of four A. calva and three P. palmas during the escape response. Both species generated high IMPs of up to 90 kPa (nearly 1 atmosphere) above ambient during the fast-start. The two species showed similar pressure magnitudes but had significantly different motor patterns and escape performance. Stage 1 of the fast-start was generated by simultaneous contraction of locomotor muscle on both sides of the body, although electromyogram amplitudes on the contralateral (convex) side of the fish were significantly lower than on the ipsilateral (concave) side. Simultaneous recordings of IMP, escape motion and muscle activity suggest that pressure change is caused by the contraction and radial swelling of cone-shaped myomeres. We develop a model of IMP production that incorporates myomere geometry, the concept of constant-volume muscular hydrostats, the relationship between fiber angle and muscle force, and the forces that muscle fibers produce. The timing profile of pressure change, behavior and muscle action indicates that elevated muscle pressure is a mechanism of stiffening the body and functions in force transmission during the escape response.

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The Role of Ca in the Regulation of Muscle Activity

The Myocardial Cell ◽

10.9783/9781512814798-007 ◽

1966 ◽

Author(s):

Annemarie Weber

Keyword(s):

Muscle Activity

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Effects of postural changes and vestibular lesions on diaphragm and rectus abdominis activity in awake cats

Journal of Applied Physiology ◽

10.1152/jappl.2001.91.1.137 ◽

2001 ◽

Vol 91 (1) ◽

pp. 137-144 ◽

Cited By ~ 31

Author(s):

L. A. Cotter ◽

H. E. Arendt ◽

J. G. Jasko ◽

C. Sprando ◽

S. P. Cass ◽

...

Keyword(s):

Vestibular System ◽

Muscle Activity ◽

Abdominal Muscle ◽

Rectus Abdominis ◽

Abdominal Muscles ◽

Body Rotation ◽

Postural Changes ◽

Before And After ◽

Awake Cats

Changes in posture can affect the resting length of the diaphragm, requiring alterations in the activity of both the abdominal muscles and the diaphragm to maintain stable ventilation. To determine the role of the vestibular system in regulating respiratory muscle discharges during postural changes, spontaneous diaphragm and rectus abdominis activity and modulation of the firing of these muscles during nose-up and ear-down tilt were compared before and after removal of labyrinthine inputs in awake cats. In vestibular-intact animals, nose-up and ear-down tilts from the prone position altered rectus abdominis firing, whereas the effects of body rotation on diaphragm activity were not statistically significant. After peripheral vestibular lesions, spontaneous diaphragm and rectus abdominis discharges increased significantly (by ∼170%), and augmentation of rectus abdominis activity during nose-up body rotation was diminished. However, spontaneous muscle activity and responses to tilt began to recover after a few days after the lesions, presumably because of plasticity in the central vestibular system. These data suggest that the vestibular system provides tonic inhibitory influences on rectus abdominis and the diaphragm and in addition contributes to eliciting increases in abdominal muscle activity during some changes in body orientation.

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Relation Between Activities of the Cortex and Vibrissae Muscles During High-Voltage Rhythmic Spike Discharges in Rats

Journal of Neurophysiology ◽

10.1152/jn.00999.2004 ◽

2005 ◽

Vol 93 (5) ◽

pp. 2435-2448 ◽

Cited By ~ 21

Author(s):

Fu-Zen Shaw ◽

Yi-Fang Liao

Keyword(s):

High Voltage ◽

Muscle Activity ◽

Oscillation Frequency ◽

Muscular Activity ◽

Simultaneous Recording ◽

Absence Seizure ◽

Mu Rhythm ◽

Oscillation Frequencies ◽

Peripheral Sensory

Paroxysmal 5- to 12-Hz high-voltage rhythmic spike (HVRS) activities, which are accompanied by whisker twitching (WT), are found in Long Evans rats, but the function of these HVRS activities is still debated. In four major functional hypotheses of HVRS discharges, i.e., alpha tremor, attention/mu rhythm, idling/mu rhythm, and absence seizure, the first two hypotheses emphasize WT behavior in HVRS bouts. Whisker movement is primarily determined by activation of intrinsic and extrinsic muscles. To clarify the role of WT in HVRS activities, simultaneous recording of the activities from the cortex and intrinsic/extrinsic and neck muscles were performed. Most HVRS bouts (68.8%) revealed no time-locked WT behavior in a 2-h recording session. In addition, WT primarily arose from active protraction due to activation of intrinsic muscles followed by passive retraction. A small portion of WT resulted from activation of both vibrissae muscles with dynamic frequency-dependent phase shifts. Onset of the rhythmic vibrissae EMG significantly lagged behind HVRS onset, and the mean duration of vibrissae muscle activity was one-third to a one-half of a HVRS bout. Moreover, a greater number of HVRS bouts were associated with a longer HVRS duration and higher oscillation frequency. Oscillation frequencies of HVRS activities without WT behavior were significantly lower than those with WT. Under peripheral sensory/motor blockade by xylocaine injection, oscillation frequencies of HVRS bouts significantly decreased, but no remarkable changes in the number or duration of HVRS bouts were observed. Compared with vibrissa muscle activity during WT and exploratory whisking, the duration of muscular activity in each cycle was apparently longer during whisking bouts. Based on these results, overemphasis of the role of WT on HVRS activities might not be appropriate. Instead, HVRS discharges may be associated with absence seizure or idling state. In addition, peripheral inputs, including WT, may elevate the oscillation frequency of HVRS bouts. Moreover, different muscular controls may exist between WT and whisking.

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