Activity in the Locust Nerve Cord in Response to Wing-Nerve Stimulation

1970 ◽  
Vol 52 (3) ◽  
pp. 667-673
Author(s):  
ERIK GETTRUP
Keyword(s):  
Nerve Stimulation ◽  
Nerve Cord ◽  
Repetitive Stimulation ◽  
Stimulation Of

1. Nerve cord activity in response to repetitive stimulation of wing nerves 1C1 and 1D was investigated in preparations of locusts. Firings of single central units occurred at latencies defined with an accuracy of few milliseconds. Various recordings of latencies show that it is not possible to exclude ganglionic synapses within the pathways considered. 2. Records from the connectives anterior to the mesothoracic ganglion or from the abdominal connectives show an increase in activity during repetitive stimulation. When recorded between prothoracic and mesothoracic ganglia a response was found in ipsilateral as well as contralateral connectives. 3. The ipsilateral and contralateral responses were delayed differently with respect to the stimulus. When nerve 1C1 of metathorax was activated the ipsilateral delay amounted to 7 msec., s.d. 2 msec., whereas the contralateral delay was found to be 8 msec., s.d. 3.4 msec. Ipsi- and contralateral latencies during stimulation of 1D of the metathorax were 5 msec., s.d. 1.4 msec.

The rapid response of Myxicola infundibulum (Grübe)

1962 ◽  
Vol 42 (3) ◽  
pp. 527-539 ◽  
Author(s):  
M. B. V. Roberts
Keyword(s):  
Nerve Cord ◽  
Escape Response ◽  
Longitudinal Muscle ◽  
Repetitive Stimulation ◽  
Rapid Response ◽  
Direct Stimulation ◽  
Giant Fibre ◽  
Single Shock ◽  
Sufficient Strength ◽  
Stimulation Of

In Myxicola the rapid muscular response produced by direct stimulation of the nerve cord with a single shock is usually large and obeys a simple ‘all-or-nothing’ relationship to the intensity of stimulation. A single shock of sufficient strength evokes a single giant fibre impulse which produces an extensive contraction of the longitudinal muscle.The magnitude of the summated contraction obtained by repetitive stimulation of the nerve cord is found to depend on the number and frequency of the shocks, thus providing the animal with a mechanism by which, theoretically, it could grade its escape response.

Non-Homogeneous Conduction In Giant Axons Of The Nerve Cord Of Periplaneta Americana

1969 ◽  
Vol 50 (3) ◽  
pp. 635-649
Author(s):  
I. PARNAS ◽  
M. E. SPIRA ◽  
R. WERMAN ◽  
F. BERGMANN
Keyword(s):  
Nerve Cord ◽  
Periplaneta Americana ◽  
Repetitive Stimulation ◽  
Low Doses ◽  
Thoracic Region ◽  
Safety Factors ◽  
Suboesophageal Ganglion ◽  
Giant Axons ◽  
Physiological Conditions ◽  
Stimulation Of

Studies with intracellular electrodes show that the abdominal giant axons of the cockroach give ascending responses to stimulation of cercal nerves and descending responses to stimulation of S0-T1 connectives. 2. In the thoracic region one or more areas of low safety factors occur for descending conduction. 3. These areas, which are considered not to be synapses, are blocked by low doses of nicotine (2-5 µg./ml.) fatigued by repetitive stimulation and show conduction delays of 0·6-0·7 msec. 4. It is concluded that the abdominal giant axons extend continuously from A6 to suboesophageal ganglion. The possibility of bi-directional conduction under physiological conditions is discussed.

Intracellular analysis of trigeminal motoneuron rhythmical activity during stimulation of pontomedullary reticular formation in anesthetized guinea pig

1989 ◽  
Vol 62 (6) ◽  
pp. 1225-1236 ◽  
Author(s):  
S. M. Gurahian ◽  
S. H. Chandler ◽  
L. J. Goldberg
Keyword(s):  
Reticular Formation ◽  
Short Duration ◽  
Field Potential ◽  
Membrane Potentials ◽  
Repetitive Stimulation ◽  
Jaw Movements ◽  
Postsynaptic Potentials ◽  
Duration Stimulus ◽  
Long Duration ◽  
Stimulation Of

1. The effects of repetitive stimulation of the nucleus pontis caudalis and nucleus gigantocellularis (PnC-Gi) of the reticular formation on jaw opener and closer motoneurons were examined. The PnC-Gi was stimulated at 75 Hz at current intensities less than 90 microA. 2. Rhythmically occurring, long-duration, depolarizing membrane potentials in jaw opener motoneurons [excitatory masticatory drive potential (E-MDP)] and long-duration hyperpolarizing membrane potentials [inhibitory masticatory drive potentials (I-MDP)] in jaw closer motoneurons were evoked by 40-Hz repetitive masticatory cortex stimulation. These potentials were completely suppressed by PnC-Gi stimulation. PnC-Gi stimulation also suppressed the short-duration, stimulus-locked depolarizations [excitatory postsynaptic potentials (EPSPs)] in jaw opener motoneurons and short-duration, stimulus-locked hyperpolarizations [inhibitory postsynaptic potentials (IPSPs)] in jaw closer motoneurons, evoked by the same repetitive cortical stimulation. 3. Short pulse train (3 pulses; 500 Hz) stimulation of the masticatory area of the cortex in the absence of rhythmical jaw movements activated the short-latency paucisynaptic corticotrigeminal pathways and evoked short-duration EPSPs and IPSPs in jaw opener and closer motoneurons, respectively. The same PnC-Gi stimulation that completely suppressed rhythmical MDPs, and stimulus-locked PSPs evoked by repetitive stimulation to the masticatory area of the cortex, produced an average reduction in PSP amplitude of 22 and 17% in jaw closer and opener motoneurons, respectively. 4. PnC-Gi stimulation produced minimal effects on the amplitude of the antidromic digastric field potential or on the intracellularly recorded antidromic digastric action potential. Moreover, PnC-Gi stimulation had little effect on jaw opener or jaw closer motoneuron membrane resting potentials in the absence of rhythmical jaw movements (RJMs). PnC-Gi stimulation produced variable effects on conductance pulses elicited in jaw opener and closer motoneurons in the absence of RJMs. 5. These results indicate that the powerful suppression of cortically evoked MDPs in opener and closer motoneurons during PnC-Gi stimulation is most likely not a result of postsynaptic inhibition of trigeminal motoneurons. It is proposed that this suppression is a result of suppression of activity in neurons responsible for masticatory rhythm generation.

Repetitive stimulation of optic nerve and lateral geniculate synapses

1959 ◽  
Vol 1 (6) ◽  
pp. 534-555 ◽  
Author(s):  
P.O. Bishop ◽  
W. Burke ◽  
W.R. Hayhow
Keyword(s):  
Optic Nerve ◽  
Repetitive Stimulation ◽  
Lateral Geniculate ◽  
Stimulation Of

Proportion of muscles spindles supplied by skeletofusimotor axons (beta-axons) in peroneus brevis muscle of the cat

1975 ◽  
Vol 38 (6) ◽  
pp. 1390-1394 ◽  
Author(s):  
F. Emonet-Denand ◽  
Y. Laporte
Keyword(s):  
Neuromuscular Junctions ◽  
Muscle Fibers ◽  
Repetitive Stimulation ◽  
Motor Axon ◽  
Dynamic Sensitivity ◽  
Conduction Velocities ◽  
Peroneus Brevis ◽  
Stimulation Of

Of 32 cat peroneus brevis spindles, 23 (72%) were found to be supplied by a least 1 skeletofusimotor or beta-axon. A motor axon was identified as skeletofusimotor when repetitive stimulation of it elicited both the contraction of extrafusal muscle fibers and as acceleration of the discharge of primary ending, which persisted after selective block of the neuromuscular junctions of extrafusal muscle fibers. The block was obtained by stimulating single axons at 400-500/s for a few seconds. Of 135 axons supplying extrafusal muscle fibers, 24 (18%) were shown to be beta-axons; 22 beta-axons had conduction velocities ranging from 45 to 75 m/s. All but three beta-axons increased the dynamic sensitivity of primary endings. Beta-innervated spindles may also be supplied by dynamic gamma-axons.

Tetanic hyperpolarization of single medullated nerve fibers in sodium and lithium

1976 ◽  
Vol 231 (4) ◽  
pp. 1033-1038 ◽  
Author(s):  
GM Schoepfle
Keyword(s):  
Steady State ◽  
Interspike Interval ◽  
Nerve Fibers ◽  
Repetitive Stimulation ◽  
Time Dependent ◽  
Potassium Ions ◽  
Current Densities ◽  
Medullated Nerve Fiber ◽  
Sodium And Potassium ◽  
Stimulation Of

Repetitive stimulation of a single medullated nerve fiber of Xenopus yields a succession of postspike voltage-time curves which are nearly coincident until attainment of a voltage that corresponds to that of the maximum attained by the normal postspike undershoot. Initially the interspike potential returns toward a resting level after this brief phase of hyperpolarization. However, as tetanization proceeds, a pattern of hyperpolarization develops with the result that, in the tetanic steady state, there exists a progressive hyperpolarization throughout each interspike interval. Extent of postspike hyperpolarization in terms of a deviation deltaVm from the resting level of membrane potential is approximated by the variation deltaVm = delta[MNa + MK]/[GNa + GK] where MNa and MK are current densities associated with active pumping of sodium and potassium ions and GNa and GK are corresponding time-dependent leak conductances. Tetanic hyperpolarization is reversibly abolished by cyanide and by exposure to lithium Ringer. Eventual reappearance of tetanic hyperpolarization in the presence of lithium Ringer suggests lithium pumping.

THE EFFECT OF THYROID HORMONE ON THE RATE OF BOTH NEUROMUSCULAR AND MUSCULAR FAILURE IN ADRENALECTOMIZED MICE MAINTAINED ON SALT

1958 ◽  
Vol 17 (2) ◽  
pp. 134-142 ◽  
Author(s):  
MARY F. LOCKETT ◽  
S. N. GANJU
Keyword(s):  
Thyroid Hormone ◽  
Thyroid Gland ◽  
Nerve Stimulation ◽  
Early Onset ◽  
Dose Effect ◽  
Muscle Fibres ◽  
Rat Diaphragm ◽  
Direct Stimulation ◽  
Normal Rat ◽  
Stimulation Of

SUMMARY Pretreatment of salt-maintained adrenalectomized mice for 6 days with 3–6 mg dried thyroid gland, or with 0·25 μg of either l-thyroxine or l-triiodothyronine, per mouse per day, delayed the early onset of both neuromuscular and muscular failure which are characteristic of these animals. Dose-effect curves for the action of thyroxine on the myoneural junctions and striped muscle fibres are given. A concentration of 0·05μg l-triiodothyronine/100 ml. bath fluid antagonized potassium reduction of the maximal twitch of the normal rat diaphragm in response to nerve stimulation, but not in response to direct stimulation of the curarized muscle.

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