A Bifunctional Single Motor Axon System of a Crustacean Muscle

1951 ◽  
Vol 28 (1) ◽  
pp. 13-21
Author(s):  
C. A. G. WIERSMA
Keyword(s):  
Hermit Crab ◽  
Motor Axon ◽  
Anatomical Features ◽  
Single Motor ◽  
Crustacean Muscle ◽  
Stimulation Of

It is shown that the opener muscle of the hermit crab, Eupagurus bernhardus L., receives a single motor axon. Stimulation of this axon results, when appropriate stimuli are used, in two types of contractions comparable with the fast and slow contractions of doubly motor-innervated crustacean muscles. The theoretical implications of this finding are discussed and a hypothesis offered to explain the mechanism which makes the two contraction types possible. The physiological and anatomical features of the innervation of the four most distal muscles in the legs of Eupagurus are described.

Excitation and Inhibition of the Reflex Eye Withdrawal of The Crab Carcinus

1967 ◽  
Vol 46 (3) ◽  
pp. 475-485
Author(s):  
D. C. SANDEMAN
Keyword(s):  
Motor Neuron ◽  
Optic Tract ◽  
The Body ◽  
Motor Axon ◽  
Single Motor ◽  
Burst Length ◽  
The Brain ◽  
Cathodal Stimulation ◽  
Stimulation Of

1. Damage to the statocysts or section of the oesophageal connectives of Carcinus causes repeated ‘spontaneous’ eye withdrawals or ‘blinking’ on the damaged side. 2. When the eyes and brain are isolated from the body, repetitive blinking persists and concomitant bursts of large impulses appear in a single motor axon in the optic tract. The length of these bursts varies from 80 to 180 impulses and the interburst intervals from 5 to 60 sec. There is no obvious correlation between burst length and interburst interval. 3. The bursts are inhibited by stimulating the inside half of the ipsilateral oesophageal connective or initiated by stimulation of the oculomotor and tegumentary nerves. If stimulated with a continuous train of pulses these pathways also cause an increase or decrease in the interburst intervals. 4. The actively spiking portion of the eye-withdrawal motor neuron extends into the brain at least as far as the tegumentary/antennary neuropile. Here it is particularly sensitive to cathodal stimulation, yielding trains of spikes to maintained d.c. stimulation. This point is considered to be near the spike initiating locus for the bursts.

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.

Reflex responses in active muscles elicited by stimulation of low-threshold afferents from the human foot

1992 ◽  
Vol 67 (5) ◽  
pp. 1375-1384 ◽  
Author(s):  
A. M. Aniss ◽  
S. C. Gandevia ◽  
D. Burke
Keyword(s):  
Motor Units ◽  
Medial Gastrocnemius ◽  
Emg Activity ◽  
Onset Latency ◽  
Single Motor ◽  
Reflex Responses ◽  
Posterior Tibial ◽  
Single Motor Units ◽  
Low Threshold ◽  
Stimulation Of

1. Reflex responses were elicited in muscles that act at the ankle by electrical stimulation of low-threshold afferents from the foot in human subjects who were reclining supine. During steady voluntary contractions, stimulus trains (5 pulses at 300 Hz) were delivered at two intensities to the sural nerve (1.2-4.0 times sensory threshold) or to the posterior tibial nerve (1.1-3.0 times motor threshold for the intrinsic muscles of the foot). Electromyographic (EMG) recordings were made from tibialis anterior (TA), peroneus longus (PL), soleus (SOL), medial gastrocnemius (MG), and lateral gastrocnemius (LG) muscles by the use of intramuscular wire electrodes. 2. As assessed by averages of rectified EMG, stimulation of the sural or posterior tibial nerves at nonpainful levels evoked a complex oscillation with onset latencies as early as 40 ms and lasting up to 200 ms in each muscle. The most common initial responses in TA were a decrease in EMG activity at an onset latency of 54 ms for sural stimuli, and an increase at an onset latency of 49 ms for posterior tibial stimuli. The response of PL to stimulation of the two nerves began with a strong facilitation of 44 ms (sural) and 49 ms (posterior tibial). With SOL, stimulation of both nerves produced early inhibition beginning at 45 and 50 ms, respectively. With both LG and MG, sural stimuli produced an early facilitation at 52-53 ms. However, posterior tibial stimuli produced different initial responses in these two muscles: facilitation in LG at 50 ms and inhibition in MG at 51 ms. 3. Perstimulus time histograms of the discharge of 61 single motor units revealed generally similar reflex responses as in multiunit EMG. However, different reflex components were not equally apparent in the responses of different single motor units: an individual motor unit could respond slightly differently with a change in stimulus intensity or background contraction level. The multiunit EMG record represents a global average that does not necessarily depict the precise pattern of all motor units contributing to the average. 4. When subjects stood erect without support and with eyes closed, reflex patterns were seen only in active muscles, and the patterns were similar to those in the reclining posture. 5. It is concluded that afferents from mechanoreceptors in the sole of the foot have multisynaptic reflex connections with the motoneuron pools innervating the muscles that act at the ankle. When the muscles are active in standing or walking, cutaneous feedback may play a role in modulating motoneuron output and thereby contribute to stabilization of stance and gait.

The Activity of Single Motor Fibres in Arthropods I. The Dragonfly Nymph

1965 ◽  
Vol 42 (3) ◽  
pp. 447-461
Author(s):  
ANN KNIGHTS
Keyword(s):  
Electrical Stimulation ◽  
Temporal Summation ◽  
Reciprocal Relationship ◽  
Response Patterns ◽  
Insect Muscle ◽  
Frequency Sensitivity ◽  
Single Motor ◽  
Dragonfly Nymph ◽  
Central Inhibition ◽  
Stimulation Of

1. Responses to mechanical and electrical stimulation have been investigated in single motor fibres dissected in the segmental nerves of the dragonfly nymph. 2. A large proportion of fibres possessed a background discharge which was often accelerated of inhibited on stimulation. Examples of central inhibition were common. 3. Efferent responses varied in type, delay and regularity, both with the input under stimulation and with the frequency and intensity of the volley. The majority of fibres responded to stimulation of more than one nerve root. 4. In many motor fibres changes in the parameters of stimulation demonstrated a reciprocal relationship between and frequency. An enhanced responsiveness occurred with frequency increases in the range of 10-100/sec. indicatind a considerable importance of temporal summation/facilitation. 5. The characteristic frequency-sensitivity of motor fibres and the variability of their response patterns are discussed in relation to the control of insect muscle.

scholarly journals THE INTERACTION BETWEEN THE SYNAPSES OF A SINGLE MOTOR FIBER

1950 ◽  
Vol 34 (2) ◽  
pp. 137-145 ◽  
Author(s):  
C. A. G. Wiersma ◽  
R. S. Turner
Keyword(s):  
Natural Conditions ◽  
Functional Connection ◽  
Block Transmission ◽  
Single Motor ◽  
The Third ◽  
The Brain ◽  
Stimulation Of

It has been shown that stimulation of synapses of the giant motor fibers of the third roots of Cambarus clarkii can block transmission at other synapses located on the same fiber. Peripherally located synapses block most synapses which are more centrally located. The reverse is true in a small number of cases. Possible reasons for this difference are discussed. It was further found that the two medial giant fibers in fresh, carefully dissected, preparations show a functional connection in the brain. It is probable that, under natural conditions, both medial giant fibers are always active at the same time.

scholarly journals The measurement of single motor-axon recurrent inhibitory post-synaptic potentials in the cat.

1987 ◽  
Vol 388 (1) ◽  
pp. 631-651 ◽  
Author(s):  
T M Hamm ◽  
S Sasaki ◽  
D G Stuart ◽  
U Windhorst ◽  
C S Yuan
Keyword(s):  
Motor Axon ◽  
Single Motor ◽  
Synaptic Potentials

scholarly journals A Movement Generated in the Peripheral Nervous System: Rhythmic Flexion by Autotomized Legs of the Stick Insect Cuniculina Impigra

1984 ◽  
Vol 111 (1) ◽  
pp. 191-199
Author(s):  
U. BÄSSLER
Keyword(s):  
Nervous System ◽  
Electrical Stimulation ◽  
Peripheral Nervous System ◽  
Related Species ◽  
Action Potentials ◽  
Small Diameter ◽  
Stick Insect ◽  
Muscle Twitch ◽  
Single Motor ◽  
Stimulation Of

Autotomized legs of the stick insect Cuniculina impigra bend rapidly and rhythmically at the femur-tibia joint. These flexions occur at a frequency 1–6 Hz immediately after autotomy and decrease in frequency and amplitude with time. Each flexion is produced by a burst of 1–14 action potentials in a single motor axon of the flexor tibiae muscle (bursting axon). These rhythmic discharges are generated in a very restricted part of the crural nerve, which contains the bursting axon, close to the autotomy point and appear whenever the nerve is cut in the immediate vicinity of this generator region. Rhythmic flexion can also be elicited by electrical stimulation of the crural nerve. The bursting axon is of small diameter. It innervates all or most of flexor tibiae muscle in which it produces relatively large EPSPs. Each EPSP elicits one muscle twitch. These fuse into a brief tetanus, whose amplitude is proportional to the number of spikes in a burst. Each tetanus produces one flexion. This behaviour does not occur in the autotomized legs of several related species.

Single motor axon conduction velocities of human upper and lower limb motor units. A study with transcranial electrical stimulation

2002 ◽  
Vol 113 (2) ◽  
pp. 284-291 ◽  
Author(s):  
Francesca Dalpozzo ◽  
Pascale Gérard ◽  
Victor De Pasqua ◽  
François Wang ◽  
Alain Maertens de Noordhout
Keyword(s):  
Electrical Stimulation ◽  
Lower Limb ◽  
Motor Units ◽  
Motor Axon ◽  
Transcranial Electrical Stimulation ◽  
Single Motor ◽  
Conduction Velocities
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