The Involvement of Nerves in the Epithelial Control of Crumpling Behaviour in a Hydrozoan Jellyfish

1981 ◽  
Vol 94 (1) ◽  
pp. 203-218 ◽  
Author(s):  
MICHAEL G. KING ◽  
ANDREW N. SPENCER
Keyword(s):  
Radial Nerve ◽  
Recording Electrode ◽  
Polyorchis Penicillatus ◽  
Nerve Bundles ◽  
Synaptic Junctions ◽  
Stimulating Electrodes ◽  
Nerve Muscle ◽  
Radial Muscle ◽  
Muscle Potential

1. The excitation pathways mediating the protective crumpling behaviour of Polyorchis penicillatus were studied with electrophysiological and ultrastructural techniques. 2. Stimulating the subumbrellar endoderm consistently resulted in a complex crumpling potential when recorded with suction electrodes from radial muscle (the prime effector). The potential represents the summation of a quick radial muscle potential (RMP) and a slow endodermal canal pulse (ECP). 3. The latencies of ECPs recorded from radial muscle during crumpling were directly proportional to the distance between the recording electrode and the subumbrellar stimulating electrode. Conversely, the latencies of RMPs, which were not tightly time-coupled to ECPs, were more directly related to the distance of the recording and stimulating electrodes from the marginal or apical termini of the radial muscle. 4. Stimulating the exumbrellar ectoderm resulted in a variable crumpling response, typically occurring after facilitation of numerous exumbrellar pulses (EPs). Since exumbrellar stimulation did not usually excite endoderm, the response recorded from radial muscle normally involved a simple RMP, un-associated with an ECP. 5. Typical synaptic junctions were observed between radial muscle processes and marginal neurites and between radial muscle and neurites of the radial nerve bundles along the length of the muscle. 6. The independence of the ECP and RMP conducting pathways demonstrates that endoderm does not provide the direct source of radial muscle excitation and the initiation of RMPs at points of known (marginal) and suspected (apical) nerve-muscle contact suggests the involvement of nerves in the control of crumpling behaviour. 7. These results are discussed in the light of other examples of active neuronal-epithelial interaction.

scholarly journals Studies on the Myoneural Physiology of Echinodermata

1955 ◽  
Vol 32 (1) ◽  
pp. 59-69
Author(s):  
WALTER POPLE ◽  
D. W. EWER
Keyword(s):  
Radial Nerve ◽  
Nerve Ring ◽  
Delayed Response ◽  
High Frequencies ◽  
Nerve Tracts ◽  
Synaptic Junctions ◽  
Post Tetanic Potentiation ◽  
Frequency Of Stimulation ◽  
Nervous Conduction ◽  
Delayed Responses

1. The general characteristics of circumoral nervous conduction in Cucumaria have been studied by the use of preparations consisting of the retractor muscles and radial nerves of two adjoining radii joined by a sector of circumoral nerve ring and by the use of similar preparations of all five retractor muscles and the complete circumoral nerve ring. 2. The characteristics of the responses of muscles stimulated by way of circumoral nerve tracts are as follows: the muscles respond with a quick and a delayed response; the magnitude of these responses depends upon the intensity of stimulation applied to an adjoining radial nerve, but is unaffected by frequency of stimulation up to a rate of 10 s./sec.; at high frequencies of stimulation both quick and delayed responses are depressed; the conduction velocity of impulses releasing quick and delayed responses is of the same order; the delayed response may show a prolonged facilitation previously analogized with post-tetanic potentiation. In these characteristics the muscular responses to impulses conducted in the circumoral nerve tracts are similar to those found to impulses conducted in the radial nerve tracts alone. 3. When, in a preparation of the five-retractor muscles, a radial nerve is stimulated, the muscles of radii nearer the stimulated nerve contract more strongly than those of radii further away. 4. Evidence is presented in favour of the view that this ‘decremental’ effect is dependent upon the geometrical arrangement of the fibre tracts in the circumoral nerve. The effect is not dependent upon frequency-sensitive synaptic junctions nor upon proprioceptive relays.

scholarly journals An Evaluation of Eight Peripheral Nerve Stimulators for Monitoring Neuromuscular Blockade

1988 ◽  
Vol 16 (4) ◽  
pp. 464-472 ◽  
Author(s):  
G. H. Beemer ◽  
J. H. Reeves
Keyword(s):  
Peripheral Nerve ◽  
Neuromuscular Blockade ◽  
The Other ◽  
Maximum Current ◽  
Stimulating Electrodes ◽  
Nerve Muscle

The features of eight commercially available peripheral nerve stimulators were compared with those evolved as ideal for monitoring neuromuscular blockade. The pulse waveforms were satisfactory except for that delivered by the CIG series 80 nerve/muscle stimulator. The error in timing of the stimulation patterns was up to 60% in the Professional Instruments NS-2C compared with 8% or less in the other devices. All of the stimulators had maximum current outputs suitable for monitoring with surface stimulating electrodes. The current delivered by the CIG series 80 nerve/muscle stimulator and the Stimlocator SL1.4 sagged by 21% and 25% respectively during a tetanus. The Digistim III, Bard Biomedical 750 digital and the Professional Instruments NS-2C had accurate digital readouts of delivered current.

scholarly journals INFLUENCE OF ELECTRICAL STIMULATION ON Regeneration of the radial nerve in dogS

2000 ◽  
Vol 48 (1) ◽  
pp. 99-105 ◽  
Author(s):  
B. Zorko ◽  
J. Rozman ◽  
A. Seliškar
Keyword(s):  
Electrical Stimulation ◽  
Nerve Regeneration ◽  
Electric Fields ◽  
Radial Nerve ◽  
Emg Activity ◽  
Significant Difference ◽  
Stimulation Period ◽  
Left And Right ◽  
Stimulating Electrodes ◽  
The Right

The effects of biphasic electric fields on nerve regeneration that follows injury to the left radial nerve were studied in dogs by electromyography (EMG). Left and right radial nerves were crushed with a serrated haemostat. Stimulating electrodes were positioned proximally and distally to the site of the injury. The left nerves received rectangular, biphasic and current pulses (30 µA, 0.5 Hz) through the injury for two months. The right radial nerves were treated as controls and regenerated without electrical stimulation. EMG activities were recorded intramuscularly from the left and right musculus extensor digitalis communis (MEDC). Results obtained at the end of the two-month stimulation period showed a significant difference in EMG activity between the left (stimulated) and the right (non-stimulated) MEDC, suggesting that electrical treatment enhanced nerve regeneration.

The Electrical and Mechanical Events of Neuro-Muscular Transmission in the Cockroach, Periplaneta Americana (L.)

1950 ◽  
Vol 27 (1) ◽  
pp. 1-13
Author(s):  
KENNETH D. ROEDER ◽  
ELIZABETH A. WEIANT
Keyword(s):  
Structural Changes ◽  
Periplaneta Americana ◽  
Mechanical Response ◽  
Motor Nerve ◽  
Potential Gradient ◽  
Positive Sign ◽  
Direct Stimulation ◽  
Bipolar Recording ◽  
Nerve Muscle ◽  
Muscle Potential

1. A nerve-muscle preparation in the metathorax of the cockroach is described. It consists of the second tergal muscle of the trochantin (muscle 162 of Carbonell) innervated by a branch of nerve 3 A. Electrical changes are recorded from electrodes on the muscle surface, and the onset of contraction is registered by the stylus of a piezo-electric pick-up. 2. With low (3-5 per sec.) stimulation rates at room temperature the neuromuscular delay is less than 1.2 msec., and the latent period of contraction about 3.0 msec. The muscle potential is 4-5 msec. in duration, positive in sign at the muscle surface, and monophasic in form with either monopolar or bipolar recording. During excitation a potential gradient develops along the muscle, the greatest positivity being in the middle near the point of nerve entry. 3. Neither electrical nor mechanical response show gradations with changes in stimulus strength or frequency. No facilitation is evident, and the response appears to be due to stimulation of a single quick motor nerve fibre. 4. In order to study the effects of direct stimulation nerve 3 was sectioned and allowed to degenerate. All trace of the peripheral nerve stump was lost after 3 days, when the muscle became completely inexcitable to all forms of electrical stimulation. There were no gross structural changes which would account for this loss of excitability. 5. It is concluded that the recorded muscle potential in the cockroach is analogous to the vertebrate end-plate potential, being the sum of local muscle potentials developing simultaneously in several fibres, and sequentially at several innervation points along the same fibre. Conduction within the muscle is carried out entirely by motor nerve fibres. 6. Possible causes of the positive sign of the muscle during activity are discussed.

Effects of carbamylcholine on chick embryo aggregate retina cell cultures

1988 ◽  
Vol 46 ◽  
pp. 350-351
Author(s):  
Glenn M. Cohen ◽  
Radharaman Ray
Keyword(s):  
Cell Cultures ◽  
Single Cells ◽  
Retinal Cell ◽  
Cell Aggregates ◽  
High Concentration ◽  
In Ovo ◽  
Sterile Culture ◽  
Retinal Tissue ◽  
Synaptic Junctions ◽  
And Control

Retinal,cell aggregates develop in culture in a pattern similar to the in ovo retina, forming neurites first and then synapses. In the present study, we continuously exposed chick retinal cell aggregates to a high concentration (1 mM) of carbamylcholine (carbachol), an acetylcholine (ACh) analog that resists hydrolysis by acetylcholinesterase (AChE). This situation is similar to organophosphorus anticholinesterase poisoning in which the ACh level is elevated at synaptic junctions due to inhibition of AChE, Our objective was to determine whether continuous carbachol exposure either damaged cholino- ceptive neurites, cell bodies, and synaptic elements of the aggregates or influenced (hastened or retarded) their development.The retinal tissue was isolated aseptically from 11 day embryonic White Leghorn chicks and then enzymatically (trypsin) and mechanically (trituration) dissociated into single cells. After washing the cells by repeated suspension and low (about 200 x G) centrifugation twice, aggregate cell cultures (about l0 cells/culture) were initiated in 1.5 ml medium (BME, GIBCO) in 35 mm sterile culture dishes and maintained as experimental (containing 10-3 M carbachol) and control specimens.

The Lateral Giant Fiber to Motor Giant Fiber Synapse in Crayfish

1972 ◽  
Vol 30 ◽  
pp. 170-171
Author(s):  
Charles A. Stirling
Keyword(s):  
Synaptic Vesicles ◽  
Procambarus Clarkii ◽  
Synaptic Contact ◽  
Giant Fiber ◽  
Synaptic Junctions

The lateral giant (LG) to motor giant (MoG) synapses in crayfish (Procambarus clarkii) abdominal ganglia are the classic electrotonic synapses. They have previously been described as having synaptic vesicles and as having them on both the pre- and postsynaptic sides of symmetrical synaptic junctions. This positioning of vesicles would make these very atypical synapses, but in the present work on the crayfish Astacus pallipes the motor giant has never been found to contain any type of vesicle at its synapses with the lateral giant fiber.The lateral to motor giant fiber synapses all occur on short branches off the main giant fibers. Closely associated with these giant fiber synapses are two small presynaptic nerves which make synaptic contact with both of the giant fibers and with their small branches.

Synaptic organization of the gustatory NST

1994 ◽  
Vol 52 ◽  
pp. 150-151
Author(s):  
M. C. Whitehead
Keyword(s):  
Central Nervous System ◽  
Dendritic Spines ◽  
Fundamental Problem ◽  
Cell Types ◽  
Brain Regions ◽  
Excitatory Synapses ◽  
Solitary Tract ◽  
Synaptic Organization ◽  
Synaptic Junctions ◽  
Afferent Terminals

A fundamental problem in taste research is to determine how gustatory signals are processed and disseminated in the mammalian central nervous system. An important first step toward understanding information processing is the identification of cell types in the nucleus of the solitary tract (NST) and their synaptic relationships with oral primary afferent terminals. Facial and glossopharyngeal (LIX) terminals in the hamster were labelled with HRP, examined with EM, and characterized as containing moderate concentrations of medium-sized round vesicles, and engaging in asymmetrical synaptic junctions. Ultrastructurally the endings resemble excitatory synapses in other brain regions.Labelled facial afferent endings in the RC subdivision synapse almost exclusively with distal dendrites and dendritic spines of NST cells. Most synaptic relationships between the facial synapses and the dendrites are simple. However, 40% of facial endings engage in complex synaptic relationships within glomeruli containing unlabelled axon endings particularly ones termed "SP" endings. SP endings are densely packed with small, pleomorphic vesicles and synapse with both the facial endings and their postsynaptic dendrites by means of nearly symmetrical junctions.

Nerve-Muscle Interaction

1979 ◽  
Vol 7 (5) ◽  
pp. 1169-1169
Author(s):  
S. WONNACOTT
Keyword(s):  
Nerve Muscle

Application and Evaluation of Case-Based Learning as a Part of Early Clinical Exposure for Undergraduate Medical Education Program

2020 ◽  
Vol 5 (08) ◽  
pp. 284-288
Author(s):  
Vandana Daulatabad ◽  
Prafull K. ◽  
Dr. Surekha S. Kadadi-Patil ◽  
Ramesh S. Patil
Keyword(s):  
Medical Education ◽  
Research Centre ◽  
Muscle Physiology ◽  
Case Scenario ◽  
Clinical Exposure ◽  
Clinical Scenarios ◽  
Case Based Learning ◽  
Nerve Muscle ◽  
Case Based ◽  
Early Clinical Exposure

Introduction: Medical Education is witnessing a significant transition and global shift towards competency based medical education (CBME) which includes early clinical exposure (ECE) program to help students apply and correlate principles of preclinical subjects with clinical scenarios, in various forms and in a variety of settings. One of the easy and feasible methods of ECE being Case Based Learning (CBL), our study aimed to design a case scenario and to evaluate impact of case base learning as a part of ECE module in first year undergraduate medical teaching program in nerve muscle physiology. Methods: The present study was conducted in 96 students at Ashwini Rural Medical College Hospital and Research Centre, Solapur after obtaining institutional ethics committee approval. 3 hrs session of CBL was conducted for a case scenario on myasthenia gravis in the nerve muscle physiology module. The students’ responses on pre-test, post-test and their insights regarding the CBL were taken through a pre validated questionnaire using 5-point Likert scale. Results: High impact of CBL was seen as significant improvement in student’s performance. Maximum students felt CBL to be easy method of learning and was highly appreciated through their feedback. Conclusion: CBL was found to have positive impact on understanding and perception of topic. CBL helped students to understand, evaluate, analyze, diagnose and interpret the case, paving them towards newer approach of self-directed and vertical integrated learning. CBL is easier, feasible an effective method among other early clinical exposure methods as it involves students in deeper and self-directed active learning, encouraging and promoting them to reach higher levels of cognitive domain of Bloom’s taxonomy. This method will be very useful in its practical implementation during online classes for ECE module in the threat of COVID 19 situation as well.

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