Neuro-Muscular Mechanisms of Abdominal Pumping in the Locust

1973 ◽  
Vol 59 (1) ◽  
pp. 149-168
Author(s):  
G. W. LEWIS ◽  
P. L. MILLER ◽  
P. S. MILLS
Keyword(s):  
Schistocerca Gregaria ◽  
Longitudinal Ventilation ◽  
Inspiratory Muscles ◽  
Metathoracic Ganglion ◽  
Inspiratory Motor ◽  
Motor Neurones ◽  
Motor Nerves ◽  
Expiratory Muscles ◽  
Anterior Segments ◽  
Nerve System

1. The muscles involved in dorso-ventral and longitudinal ventilation in the pregenital segments of Schistocerca gregaria are described. Expiratory muscles are shown to be innervated by paired lateral nerves whereas the dorso-ventral inspiratory muscles are innervated by the unpaired median nerve system. 2. Normal pumping activity is brought about by alternating bursts of impulses in expiratory and inspiratory motor nerves. Inspiratory bursts are relatively invariant, whereas expiratory bursts show a positive correlation with ventilatory cycle length. The firing patterns of some units within the bursts are described. 3. In general anterior segments fire motor bursts earlier than posterior segments during well synchronized active ventilation, the metathoracic ganglion firing first. However, much variation is seen both within one locust and between different locusts. Burst-formation continues in isolated nerve cords. 4. Activity, phase-locked with expiration, has been recorded in the connectives. The evidence suggests that it occurs in a pair of co-ordinating interneurones which run from the metathoracic ganglion to the last abdominal ganglion and determine the initiation, duration and possibly the intensity of the expiratory motor bursts in each segment. A second parallel system may co-ordinate activity when the metathoracic co-ordinating interneurones are inactive. Inspiratory motor neurones are probably autoactive and the duration of their firing may normally be determined by the discharge phase of a metathoracic oscillator which acts by inhibiting the co-ordinating interneurones.

The Physiology and Morphology of Median Nerve Motor Neurones in the Thoracic Ganglia of the Locust

1982 ◽  
Vol 96 (1) ◽  
pp. 325-341
Author(s):  
MALCOLM BURROWS
Keyword(s):  
Synaptic Input ◽  
Motor Neurone ◽  
Abdominal Muscles ◽  
Thoracic Ganglia ◽  
Synaptic Potentials ◽  
Metathoracic Ganglion ◽  
Inspiratory Motor ◽  
Motor Neurones ◽  
Chemical Synapses ◽  
The Right

Simultaneous intracellular recordings have been made from the two expiratory, and from the two inspiratory motor neurones which have their axons in the unpaired median nerves of the thoracic ganglia. Each motor neurone has an axon that branches to innervate muscles on the left and on the right side of one segment. The expiratory neurones studied were those in the meso- and meta-thoracic ganglia which innervate spiracular closer muscles. The depolarizing synaptic potentials underlying the spikes during expiration are common to the two closer motor neurones in a particular segment. Similarly, during inspiration when there are usually no spikes, the hyperpolarizing, inhibitory potentials are also common to both motor neurones. The synaptic input to the neurones can be derived from four interneurones; two responsible for the depolarizing potentials during expiration and two for the inhibitory potentials during inspiration. The inspiratory neurones studied were those in the abdominal ganglia fused to the metathoracic ganglion which innervate dorso-ventral abdominal muscles. During inspiration the two motor neurones of one segment spike at a similar and steady frequency. The underlying synaptic input to the two is common. During expiration, when there are usually no spikes, the hyperpolarizing synaptic potentials are also common to both neurones. In addition they match exactly the depolarizing potentials occurring at the same time in the closer motor neurones. The same set of interneurones could be responsible. No evidence has been revealed to indicate that the two closer, or the two inspiratory motor neurones of one segment are directly coupled by electrical or chemical synapses. The morphology of both types of motor neurone is distinct from that of other motor neurones in these ganglia. Both types branch extensively in both the left and in the right areas of the neuropile.

Interrelation between lung volume, arterial CO2 tension, and respiratory activity

1965 ◽  
Vol 20 (4) ◽  
pp. 647-652 ◽  
Author(s):  
Sabbo Woldring
Keyword(s):  
Lung Volume ◽  
Respiratory Activity ◽  
Respiratory Muscles ◽  
Regulation Of Respiration ◽  
Abdominal Muscles ◽  
Pco2 Level ◽  
Arterial Pco2 ◽  
Inspiratory Muscles ◽  
Inspiratory Motor ◽  
Expiratory Muscles

In anesthetized cats with open thorax the activity of the respiratory muscles (diaphragm and abdominal muscles) is studied as a function of lung volume and arterial CO2 tension. It is shown that the sensitivity of the inspiratory muscles to a given change in lung volume (V) (Hering-Breuer reflex) varies with the arterial pCO2 level, and conversely, that the CO2 sensitivity of the inspiratory motor system is dependent upon the volume of the lungs. The relations are fairly linear and can be expressed by the equation: M — M0 = K (pa CO2 — p0) (V0 — V), in which M represents inspiratory motor activity and M0, p0, and V0 and K are constants. The activity of the expiratory muscles is not dependent on CO2. regulation of respiration; Hering-Breuer reflex; electromyography of respiratory muscles Submitted on September 24, 1964

THE HISTOLOGY OF THE GIANT FIBRE SYSTEM IN THE ABDOMINAL VENTRAL NERVE CORD OF THE DESERT LOCUST

1970 ◽  
Vol 102 (9) ◽  
pp. 1163-1168 ◽  
Author(s):  
W. D. Seabrook
Keyword(s):  
Single Cell ◽  
Nerve Cord ◽  
Ventral Nerve Cord ◽  
Schistocerca Gregaria ◽  
Desert Locust ◽  
Giant Fibre ◽  
Metathoracic Ganglion ◽  
Giant Fibres ◽  
Giant Fibre System

AbstractSchistocerca gregaria possess four neurones of giant fibre proportions within the abdominal ventral nerve cord. These fibres arise from single cell bodies in the terminal ganglionic mass and pass without interruption to the metathoracic ganglion. Fibres become reduced in diameter when passing through a ganglion. Branching of the giant fibres occurs in abdominal ganglia 6 and 7.

The vibrational startle response of the desert locust Schistocerca gregaria

1999 ◽  
Vol 202 (16) ◽  
pp. 2151-2159 ◽  
Author(s):  
T. Friedel
Keyword(s):  
Stimulus Intensity ◽  
Startle Response ◽  
Schistocerca Gregaria ◽  
Whole Body ◽  
Desert Locust ◽  
Intracellular Recordings ◽  
Stimulus Amplitude ◽  
Co Activation ◽  
Motor Neurones ◽  
Fast Twitch

Substratum vibrations elicit a fast startle response in unrestrained quiescent desert locusts (Schistocerca gregaria). The response is graded with stimulus intensity and consists of a small, rapid but conspicuous movement of the legs and body, but it does not result in any positional change of the animal. With stimuli just above threshold, it begins with a fast twitch of the hindlegs generated by movements of the coxa-trochanter and femur-tibia joints. With increasing stimulus intensity, a rapid movement of all legs may follow, resulting in an up-down movement of the whole body. The magnitude of both the hindleg movement and electromyographic recordings from hindleg extensor and flexor tibiae muscles increases with stimulus amplitude and reaches a plateau at vibration accelerations above 20 m s(−)(2) (peak-to-peak). Hindleg extensor and flexor tibiae muscles in unrestrained animals are co-activated with a mean latency of 30 ms. Behavioural thresholds are as low as 0. 47 m s(−)(2) (peak-to-peak) at frequencies below 100 Hz but rise steeply above 200 Hz. The response habituates rapidly, and inter-stimulus intervals of 2 min or more are necessary to evoke maximal reactions. Intracellular recordings in fixed (upside-down) locusts also revealed co-activation of both flexor and extensor motor neurones with latencies of approximately 25 ms. This shows that the neuronal network underlying the startle movement is functional in a restrained preparation and can therefore be studied in great detail at the level of identified neurones.

Serotonergic modulation of locust motor neurons

1995 ◽  
Vol 73 (3) ◽  
pp. 923-932 ◽  
Author(s):  
D. Parker
Keyword(s):  
Cyclic Amp ◽  
Motor Neurons ◽  
Schistocerca Gregaria ◽  
Phosphodiesterase Inhibitor ◽  
Membrane Resistance ◽  
Excitatory Postsynaptic Potential ◽  
Metathoracic Ganglion ◽  
Bath Application ◽  
Potassium Conductances ◽  
5 Ht Uptake

1. The effects of the putative endogenous neuromodulator serotonin (5-HT) on the fast extensor and flexor tibiae motor neurons in the locust (Schistocerca gregaria) metathoracic ganglion, were analyzed. 2. 5-HT consistently increased the duration of the fast extensor spike and usually reduced the afterhyperpolarization, although this effect was less consistent. The spike broadening in the fast extensor was associated with an increase in the amplitude of the excitatory postsynaptic potential (EPSP) evoked monosynaptically in the flexor motor neurons by fast extensor stimulation. 5-HT also increased the membrane resistance of the fast extensor and flexor tibiae motor neurons. 3. The effects of 5-HT were mimicked by bath application of the 5-HT uptake inhibitor imipramine, and blocked by the 5-HT receptor antagonist ketanserin. The effects were also mimicked by dibutryl cyclic AMP, a membrane permeant analogue of cyclic AMP, and by the phosphodiesterase inhibitor 3-isobutyl-1-methyl-xanthine, but not by dibutryl cyclic GMP. The 5-HT-dependent modulation was blocked by the protein kinase A inhibitor H8. In addition, injection of cyclic AMP into the fast extensor or a flexor motor neuron could mimic the effects of 5-HT on these neurons. 4. 5-HT probably broadened the FETi action potential by modulating potassium conductances responsible for spike repolarization. 5. These results show that 5-HT modulates both the fast extensor and flexor tibiae motor neurons, resulting in potentiation of synaptic transmission between these neurons. In addition, the increase in flexor membrane resistance will potentiate other inputs onto these cells, which will affect the output of the motor neurons during locomotion.

Octopamine modulates the responses and presynaptic inhibition of proprioceptive sensory neurones in the locust Schistocerca gregaria

1997 ◽  
Vol 200 (9) ◽  
pp. 1317-1325 ◽  
Author(s):  
T Matheson
Keyword(s):  
Presynaptic Inhibition ◽  
Schistocerca Gregaria ◽  
Chordotonal Organ ◽  
Mechanical Stimuli ◽  
Sensory Neurone ◽  
Tonic Component ◽  
Sensory Neurones ◽  
Phasic Component ◽  
Bath Application ◽  
Motor Neurones

A multineuronal proprioceptor, the femoral chordotonal organ (feCO), monitors the position and movements of the tibia of an insect leg. Superfusing the locust metathoracic feCO with the neuromodulator octopamine, or the octopamine agonist synephrine, affects the position (tonic) component of the organ's response, but not the movement (phasic) component. Both octopamine and synephrine act with the same threshold (10(-6) mol l-1). Individual sensory neurones that respond tonically at flexed tibial angles show increased tonic spike activity following application of octopamine, but those that respond at extended angles do not. Tonic spiking of phaso-tonic flexion-sensitive neurones is enhanced but their phasic spiking is unaffected. Bath application of octopamine to the feCO increases the tonic component of presynaptic inhibition recorded in the sensory terminals, but not the phasic component. This inhibition should at least partially counteract the increased sensory spiking and reduce its effect on postsynaptic targets such as motor neurones. Furthermore, some phasic sensory neurones whose spiking is not affected by octopamine nevertheless show enhanced tonic synaptic inputs. The chordotonal organ is not known to be under direct efferent control, but its output is modified by octopamine acting on its sensory neurones to alter their responsiveness to mechanical stimuli and by presynaptic inhibition acting on their central branches. The effects of this neuromodulator acting peripherally on sensory neurones are therefore further complicated by indirect interactions between the sensory neurones within the central nervous system. Increases of sensory neurone spiking caused by neuromodulators may not necessarily lead to parallel increases in the responses of postsynaptic target neurones.

Effects of diaphragmatic ischemia on the inspiratory motor drive

1992 ◽  
Vol 72 (2) ◽  
pp. 447-454 ◽  
Author(s):  
J. S. Teitelbaum ◽  
S. A. Magder ◽  
C. Roussos ◽  
S. N. Hussain
Keyword(s):  
Muscle Activation ◽  
Systemic Circulation ◽  
Progressive Increase ◽  
Emg Activity ◽  
Motor Drive ◽  
Inspiratory Muscles ◽  
Left Diaphragm ◽  
Inspiratory Motor ◽  
Phrenic Artery ◽  
Left And Right

To assess the effect of diaphragmatic ischemia on the inspiratory motor drive, we studied the in situ isolated and innervated left diaphragm in anesthetized, vagotomized, and mechanically ventilated dogs. The arterial and venous vessels of the left diaphragm were catheterized and isolated from the systemic circulation. Inspiratory muscle activation was assessed by recording the integrated electromyographic (EMG) activity of the left and right costal diaphragms and parasternal intercostal and alae nasi muscles. Tension generated by the left diaphragm during spontaneous breathing attempts was also measured. In eight animals, left diaphragmatic ischemia was induced by occluding the phrenic artery for 20 min, followed by 10 min of reperfusion. This elicited a progressive increase in EMG activity of the left and right diaphragms and parasternal and alae nasi muscles to 170, 157, 152, and 128% of baseline values, respectively, an increase in the frequency of breathing efforts, and no change in left diaphragmatic spontaneous tension. Thus the ratio of left diaphragmatic EMG to tension rose progressively during ischemia. During reperfusion, only the frequency of breathing efforts and alae nasi EMG recovered completely. In four additional animals, left diaphragmatic ischemia was induced after the left phrenic nerve was sectioned. Neither EMG activity of inspiratory muscles nor respiratory timing changed significantly during ischemia. In conclusion, diaphragmatic ischemia increases inspiratory motor drive through activation of phrenic afferents. The changes in alae nasi activity and respiratory timing indicate that this influence is achieved through supraspinal pathways.

Electrical activation of expiratory muscles increases with time in pentobarbital-anesthetized dogs

1992 ◽  
Vol 72 (6) ◽  
pp. 2285-2291 ◽  
Author(s):  
D. O. Warner ◽  
M. J. Joyner ◽  
K. Rehder
Keyword(s):  
Electrical Activity ◽  
Important Variable ◽  
Transversus Abdominis ◽  
Implanted Electrodes ◽  
Expiratory Muscle ◽  
Inspiratory Muscles ◽  
Anesthetized Dogs ◽  
Expiratory Muscles ◽  
Muscle Groups ◽  
Over Time

Although the pentobarbital-anesthetized dog is often used as a model in studies of respiratory muscle activity during spontaneous breathing, there is no information regarding the stability of the pattern of breathing of this model over time. The electromyograms of several inspiratory and expiratory muscle groups were measured in six dogs over a 4-h period by use of chronically implanted electrodes. Anesthesia was induced with pentobarbital sodium (25 mg/kg iv), with supplemental doses to maintain constant plasma pentobarbital concentrations. Phasic electrical activity increased over time in the triangularis sterni, transversus abdominis, and external oblique muscles (expiratory muscles). The electrical activity of the costal diaphragm, crural diaphragm, and parasternal intercostal muscles (inspiratory muscles) was unchanged. These changes in electrical activity occurred despite stable plasma levels of pentobarbital and arterial PCO2. They were associated with changes in chest wall motion and an increased tidal volume with unchanged breathing frequency. We conclude that expiratory muscle groups are selectively activated with time in pentobarbital-anesthetized dogs lying supine. Therefore the duration of anesthesia is an important variable in studies using this model.

scholarly journals Innervation patterns of inhibitory motor neurones in the thorax of the locust

1985 ◽  
Vol 117 (1) ◽  
pp. 401-413 ◽  
Author(s):  
J. P. Hale ◽  
M. Burrows
Keyword(s):  
Intracellular Recording ◽  
Simultaneous Recording ◽  
Muscle Fibres ◽  
Innervation Pattern ◽  
Synaptic Coupling ◽  
Synaptic Inputs ◽  
Metathoracic Ganglion ◽  
Innervation Patterns ◽  
Motor Neurones ◽  
The Common

The innervation pattern of inhibitory motor neurones of the locust has been revealed by intracellular recording from their cell bodies in the meso- and metathoracic ganglion and simultaneous recording from muscle fibres in a middle, or in a hind leg. Three neurones in each ganglion, the common inhibitor (CI = CI1), the anterior inhibitor (AI = CI2), and the posterior inhibitor (PI = CI3) innervate several muscles in one leg and are thus common inhibitory neurones. Metathoracic CI innervates 13 muscles in one hind leg and mesothoracic CI innervates 12 muscles in one middle leg. The muscles are all in the proximal parts of the legs and move the coxa, the trochanter and the tibia. Metathoracic AI and PI innervate four muscles in the more distal parts of one hind leg that move the tibia, the tarsus and the unguis. None of these muscles is innervated by CI. Each inhibitor innervates muscles that have different and often antagonistic actions during movements of a leg. AI and PI receive many synaptic inputs in common and show similar patterns of spikes during imposed movements of a tibia. Tests fail, however, to reveal evidence for any electrical or synaptic coupling between them. A revised scheme of nomenclature for these inhibitory neurones is proposed.

scholarly journals The Identification of Motor Neurones Innervating an Abdominal Ventilatory Muscle in the Locust

1983 ◽  
Vol 107 (1) ◽  
pp. 115-127 ◽  
Author(s):  
QIN-ZHAO YANG
Keyword(s):  
Cell Body ◽  
Contralateral Side ◽  
The Body ◽  
Dorsal Muscle ◽  
The Third ◽  
Metathoracic Ganglion ◽  
Motor Neurones ◽  
Left And Right ◽  
Ventral Muscle ◽  
Ventilatory Muscles

Motor neurones to abdominal ventilatory muscles, with their axons innerve 6 of the metathoracic ganglion of the locust, have been identified by intracellular recording and staining. Three muscles are innervated by the larger branches of this nerve: nerve 6a contains six motor neurones innervating the ventral diaphragm; nerve 6b contains four motor neurones innervating the median internal ventral muscle, and nerve 6d contains five motorneurones innervating the longitudinal dorsal muscle. All motor neuronesinnervate muscles on one side of the body only. Both the median internalventral and the longitudinal dorsal muscles contract during the expiratoryphase of ventilation. Three excitatory motor neurones to the median internalventral muscles spike during expiration whilst the fourth, an inhibitorymotor neurone, is active during both expiration and inspiration. Two of theexcitatory motor neurones have cell bodies in the half of the ganglion ipsilateralto the muscle they innervate. Their neuropilar branches, however, are in both left and right halves of the ganglion. The third excitatory motorneurone has its cell body close to the midline and has most of its neuropilarbranches in the half of the ganglion ipsilateral to its axon. The inhibitorymotor neurone has its cell body just to the contralateral side of the midline, and three distinct areas of neuropilar branches, two contralateral and oneipsilateral to its axon.

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