The Behaviour and Neuromuscular System of Gonactinia Prolifera, A Swimming Sea-Anemone

1971 ◽  
Vol 55 (3) ◽  
pp. 611-640
Author(s):  
ELAINE A. ROBSON
Keyword(s):  
Electrical Stimulation ◽  
Mechanical Stimulation ◽  
Motor Units ◽  
Nerve Cells ◽  
Sea Anemone ◽  
Neuromuscular System ◽  
Sea Anemones ◽  
Nerve Net ◽  
Local Contraction ◽  
Electric Shocks

1. In Gonactinia well-developed ectodermal muscle and nerve-net extend over the column and crown and play an important part in the anemone's behaviour. 2. Common sequences of behaviour are described. Feeding is a series of reflex contractions of different muscles by means of which plankton is caught and swallowed. Walking, in the form of brief looping steps, differs markedly in that it continues after interruptions. Anemones also swim with rapid tentacle strokes after contact with certain nudibranch molluscs, strong mechanical disturbance or electrical stimulation. 3. Swimming is attributed to temporary excitation of a diffuse ectodermal pacemaker possibly situated in the upper column. 4. From the results of electrical and mechanical stimulation it is concluded that the endodermal neuromuscular system resembles that of other anemones but that the properties of the ectodermal neuromuscular system require a new explanation. The size and spread of responses to electric shocks vary with intensity, latency is variable and there is a tendency to after-discharge. There is precise radial localization, for example touching a tentacle or the column causes it to bend towards or away from the stimulus. 5. A model to explain these and other features includes multipolar nerve cells closely linked to the nerve-net which would act as intermediate motor units, causing local contraction of the ectodermal muscle. This scheme can be applied to other swimming anemones but there is no evidence that it holds for sea anemones generally.

scholarly journals Nerve Net Pacemakers and Phases of Behaviour in the Sea Anemone Calliactis Parasitica

1983 ◽  
Vol 104 (1) ◽  
pp. 231-246
Author(s):  
IAN D. McFARLANE
Keyword(s):  
Electrical Stimulation ◽  
Pulse Number ◽  
Sea Anemone ◽  
Sea Anemones ◽  
Nerve Net ◽  
Partial Activation ◽  
Calliactis Parasitica ◽  
Slow System ◽  
Stimulation Of

Bursts of through-conducting nerve net (TCNN) pulses, 20–45 min apart, were recorded from Calliactis attached to shells. Within 15–25 min of the anemones being detached the TCNN bursts suddenly became more frequent (only 4–11 min apart). Such bursts continued for several hours if re-attachment was prevented. In an attached anemone simultaneous electrical stimulation of the TCNN and ectodermal slow system (SS1) with 20–30 shocks at one every 5 s also led to more frequent TCNN bursts, whether or not detachment took place. If, however, the anemone remained attached, the intervals between bursts returned to the normal resting duration after about 90 min. In all cases the decay of the 4–11 min interval TCNN bursts involved a reduction in pulse number, not an increase in burst interval. Partial activation of the TCNN pacemakers followed stimulation of the SS1 alone. It is suggested that in sea anemones the change from one behavioural phase to another is associated with a change in the patterned output of nerve net pacemakers.

Control of mouth opening and pharynx protrusion during feeding in the sea anemone Calliactis parasitica

1975 ◽  
Vol 63 (3) ◽  
pp. 615-626
Author(s):  
I. D. McFarlane
Keyword(s):  
Amino Acids ◽  
Electrical Stimulation ◽  
Reduced Glutathione ◽  
Mouth Opening ◽  
Pulse Frequency ◽  
Sea Anemone ◽  
Conducting System ◽  
Nerve Net ◽  
Calliactis Parasitica ◽  
Stimulation Of

1. Activity in all three known conducting systems (the nerve net, SS1, and SS2) may accompany feeding in Calliactis. The most marked response is an increase in pulse frequency in the SS2 (the endodermal slow conducting system) during mouth opening and pharynx protrusion. 2. Electrical stimulation of the SS2 at a frequency of one shock every 5 s elicits mouth opening and pharynx protrusion in the absence of food. 3. A rise in SS2 pulse frequency is also evoked by food extracts, some amino acids, and in particular by the tripeptide reduced glutathione, which produces a response at a concentration of 10(−5) M. 4. Although the SS2 is an endodermal system, the receptors involved in the response to food appear to be ectodermal. 5. The epithelium that lines the pharynx conducts SS1 pulses, but there is some evidence for polarization of conduction.

Long-Term Facilitation in a Swimming Sea Anemone

1959 ◽  
Vol 36 (3) ◽  
pp. 526-532
Author(s):  
DONALD M. WILSON
Keyword(s):  
Sea Anemone ◽  
Experimental Techniques ◽  
Frequency Range ◽  
Nerve Net ◽  
Electric Shocks ◽  
Electrical Shocks ◽  
Probable Site ◽  
A Chain ◽  
Long Term Facilitation

1. Repetition-produced modifications in the behaviour of the swimming sea anemone, Stomphia coccinea, are described. Lowered threshold to number of electrical shocks on successive trials indicates a kind of ‘learning‘ called here longterm facilitation. 2. Dissection of the behaviour into its components, both by experimental techniques and observation of atypical cases, shows the swimming reaction not to be simply a chain of reflexes, but to be ‘centrally’; co-ordinated. 3. The conditions for electrical elicitation of swimming are shocks sufficient in intensity to activate the through-conducting nerve net repeated eight times in the frequency range of 1/2 sec. to 4/sec. Fewer than 8 shocks constitute a subthreshold stimulus in fresh animals; more than 8 are rarely required. 4. Repeated subthreshold stimulation by starfish or by 7 electric shocks result in a long-lasting facilitated state in which the same stimulus repeated hours later may produce a full response. The facilitated condition has been observed to last 7 days. Controls kept without stimulation do not show facilitation. 5. The probable site of this long-term facilitation is discussed. It is suggested that this site is at the point of convergence of the two types of stimulation used and between the through-conducting nerve net and the responding muscles.

Excitatory Actions of Antho-RFamide, An Anthozoan Neuropeptide, on Muscles and Conducting Systems in the Sea Anemone Calliactis Parasitica

1987 ◽  
Vol 133 (1) ◽  
pp. 157-168 ◽  
Author(s):  
I. D. McFARLANE ◽  
D. GRAFF ◽  
C. J.P. GRIMMELIKHUIJZEN
Keyword(s):  
Electrical Activity ◽  
Slow Muscle ◽  
Conduction System ◽  
Sea Anemone ◽  
Sea Anemones ◽  
Nerve Net ◽  
Direct Excitation ◽  
Calliactis Parasitica ◽  
Muscle Groups ◽  
Fast Muscles

In the sea anemone Calliactis parasitica endodermal application of the anthozoan neuropeptide Antho-RFamide (<Glu-Gly-Arg-Phe-amide), at a concentration of 10−6 or 10−7moll−1, caused a long-lasting increase in tone, contraction frequency and contraction amplitude in several slow muscle groups but had no effect on contractions in fast muscles. The effects were investigated further in isolated muscle preparations. Ectodermal application to whole animals had no effect on muscle contractions. Both ectodermal and endodermal application, at 10−7moll−1, raised electrical activity in an ectodermal conduction system, the SSI, but had no effect on an endodermal conduction system, the SS2. Electrical activity in the SS2 was increased by application at 10−6moll−1 to the endoderm but not to the ectoderm. The peptide had no effect on the through-conducting nerve net. It is concluded that contractions evoked by Antho-RFamide may be partly due to neuronal activity, but probably also involve direct excitation of the muscles. The diverse excitatory actions of Antho-RFamide suggest that it may be a neurotransmitter or neuromodulator in sea anemones.

scholarly journals Observations on Luminescence in Renilla (Pennatulacea)

1955 ◽  
Vol 32 (2) ◽  
pp. 299-320
Author(s):  
J. A. C. NICOL
Keyword(s):  
Electrical Stimulation ◽  
Latent Period ◽  
Mechanical Stimulation ◽  
Response Rate ◽  
Flash Duration ◽  
Entire Surface ◽  
Response Intensity ◽  
Nerve Net ◽  
Light Waves ◽  
Conducting Mechanism

1. Luminescent responses in the sea pansy Renilla köllikeri take the form of light waves which run over the entire surface of the rachis. As other workers have shown, the responses are controlled by an unpolarized nerve net, and are subject to facilitation. Records obtained by photoelectric techniques are furnished to show certain features of the response. 2. At moderate rates of electrical stimulation (1 per sec.), 2-3 shocks are required to evoke a response. At slower rates, more stimuli are necessary owing to decay of facilitator. At frequencies above 3 per sec., the response rate is slower than the stimulation frequency, owing to refractoriness in the conducting mechanism (c. 0.2 sec.). 3. Summation occurs at frequencies above 1 per sec. This results largely from fusion of the more persistent glowing of autozooids. Siphonozooids are responsible for the brief flashes. 4. Maximal estimates of latent period and flash-duration are of the order of 0.5 and 0.9 sec. respectively. 5. With repeated stimulation, the response intensity is subject to decay. Experiments suggest that this is a consequence of exhaustion of photogenic material. 6. On mechanical stimulation, luminescent waves are evoked at first; but with continued stimulation, refractoriness sets in, and responses become localized to the area of stimulation. Subsequent electrical stimulation reveals that the transmitter mechanism is fatigued, and excitability gradually returns over the course of the next 30-60 mm.

Observations on luminescence in sea pens (Pennatulacea)

1956 ◽  
Vol 144 (917) ◽  
pp. 480-496 ◽  
Keyword(s):  
Electrical Stimulation ◽  
Latent Period ◽  
Mechanical Stimulation ◽  
Total Duration ◽  
Visual Observation ◽  
Repetitive Stimulation ◽  
Half Maximum ◽  
Nerve Net ◽  
Refractory State ◽  
Lines Of Evidence

The luminescent responses of sea pens ( Leioptilus gurneyi ) have been studied by visual observation and photo-electric recording. Light is emitted by the polyps (autozooids and siphonozooids) when the animal is excited. Gentle mechanical stimulation and electrical stimulation (condenser shocks) evoke luminescent waves which pass over the rachis at a velocity of 26·4 cm/s (20·5°C). The first luminescent wave appears after 1 to 3 shocks, depending on the condition of the animal. Subsequently, waves arise at the rate of 1/shock, and increase progressively in intensity owing to neuroeffector facilitation. On recording from re-­stricted loci (width 2 cm), the following data for temporal characteristics of flashes (from auto ­zooids) were obtained: latent period, 0·18s; total duration of flash, 1 to 1·2s; maximal intensity from first deflexion, 0·2 s; time to half-maximum, 0·1 s. Strong mechanical and prolonged electrical stimulation produce a refractory state in which the animal contracts and no longer produces luminescent waves. Slow progressive spread of luminescence can then be induced by maintained repetitive stimulation. This effect is ascribed to intemuncial facilitation overcoming fatigue in the nerve net. Certain lines of evidence indicate that light may temporarily inhibit luminescence, apparently by affecting the excitatory system. The results are related to observations made on the luminescent responses of other sea pens.

A Comparison of the Nervous Systems of two Sea-Anemones, Calliactis parasitica and Metridium senile

1961 ◽  
Vol s3-102 (59) ◽  
pp. 319-326
Author(s):  
ELAINE A. ROBSON
Keyword(s):  
Methylene Blue ◽  
Nervous System ◽  
Conduction System ◽  
Nerve Cells ◽  
Bipolar Cells ◽  
Retractor Muscle ◽  
Sea Anemones ◽  
Nerve Net ◽  
Metridium Senile ◽  
Calliactis Parasitica

The properties of the actinian nervous system are known mainly from physiological experiments on Calliactis parasitica (Couch), and from histological work on Metridium senile (L.). The structure of the nerve-net in the mesenteries of Calliactis is now shown to resemble in general that in Metridium. Methylene blue stains a network of bipolar cells over the retractor muscle, together with sense-cells, and unlike Metridium, multipolar nerve-cells. The nerve-net over the radial surface of the mesentery is similarly much sparser. The distribution of nerve-cells and sense-cells in the column also resembles that in Metridium. Experiments on Metridium show that as in Calliactis, the rate of conduction in the mesenteries is greater than in other parts of the anemone. The column, including the sphincter region, conducts more slowly. It is thus shown that the presence of a well developed nerve-net over the retractors is associated with the development of fast tracts in the through-conduction system, and of rapid, facilitated contractions of the retractor muscles, in both species of anemone.

scholarly journals The Nerve-Net of the Sea-Anemone Metridium Senile: the Mesenteries and the Column

1960 ◽  
Vol s3-101 (56) ◽  
pp. 487-510
Author(s):  
E. J. BATHAM ◽  
C. F. A. PANTIN ◽  
E. A. ROBSON
Keyword(s):  
Methylene Blue ◽  
Reciprocal Inhibition ◽  
Nerve Cells ◽  
Sea Anemone ◽  
Nerve Net ◽  
Metridium Senile ◽  
Physiological Evidence ◽  
Staining Methods

The actinian nerve-net has been examined in the mesenteries and column of Metridium senile (L.) after staining with silver and with methylene blue. Modified staining methods are described. The synaptic nature of the junctions between bipolar nerve-cells, of their expanded terminations over the muscle-field, and of their contacts with the neurites of sense-cells is reviewed. The neurites always run in the space between the epithelium and underlying muscle. They follow the distribution of the main contractile systems, including the passage of circular fibres beneath the mesenteries. The richerinnervation of the retractor surface of a mesentery compared to the radial is correlated with the ability of this hypertrophied muscle to contract rapidly. The distribution of nerve-cells and sense-cells in the mesenteries and column is related to physiological evidence concerning the through-conduction pathways, facilitated and slow contractions, and other aspects of the behaviour of Metridium. It is concluded that although features such as reciprocal inhibition in the column are still unexplained, there is as yet no histological or physiological evidence for double innervation of the musclesin this anemone. The terminations of sensory neurites, on musclefibres or elsewhere, have not yet been seen in any actinian

Colonial behaviour and electrical activity in the Hexacorallia

1975 ◽  
Vol 190 (1099) ◽  
pp. 239-256 ◽  
Keyword(s):  
Electrical Stimulation ◽  
Electrical Activity ◽  
Neuromuscular Junctions ◽  
Electrical Potential ◽  
Pulse Frequency ◽  
Mechanical Stimulus ◽  
Time Interval ◽  
Short Time Interval ◽  
Sea Anemones ◽  
Nerve Net

The behaviour of the polyps of eight coral species in the subclass Hexacorallia is described with reference to electrical activity recorded with extracellular suction electrodes. Following repetitive mechanical or electrical stimulation, waves of polyp retraction spread over the colony from the point of stimulation. In response to a single electrical or mechanical stimulus, a single electrical potential was evoked. It is suggested that this pulse represented activity in the colonial nerve net. The pulse was conducted without decrement over large areas of the colony. The conduction velocity was 15-25 cm s -1 at 25°C. There was no evidence for multiple firing following single threshold stimuli. Polyp retraction only occurred after two or more ‘nerve net' pulses had impinged upon the neuromuscular junctions of the retractor muscles within a short time interval. Colonial polyp retraction responses occurred, therefore, when a number of nerve net pulses were conducted across the colonial nerve net. A burst of pulses showed a reduction in frequency as it was conducted from the point of stimulation. A new explanation of colonial polyp retraction patterns in response to electrical stimulation is proposed. The different patterns may be explained in terms of the way in which the frequency (but not the number) of the pulses in a burst of nerve net activity changes with the distance conducted. Changes in nerve net pulse frequency affect the degree of facilitation of the neuromuscular junctions which, in turn, affects the size of the muscle contraction evoked. The possibility is considered that ‘slow conduction systems’ similar to those found in sea anemones may also be present in the colonial Hexacorallia.

scholarly journals Modulation of torque evoked by wide-pulse, high-frequency neuromuscular electrical stimulation and the potential implications for rehabilitation and training

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Chris Donnelly ◽  
Jonathan Stegmüller ◽  
Anthony J. Blazevich ◽  
Fabienne Crettaz von Roten ◽  
Bengt Kayser ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
High Frequency ◽  
Neuromuscular Electrical Stimulation ◽  
Motor Units ◽  
Progressive Increase ◽  
Great Promise ◽  
Measured Parameter ◽  
Time Integral ◽  
Spinal Circuitry ◽  
Evoked Force

AbstractThe effectiveness of neuromuscular electrical stimulation (NMES) for rehabilitation is proportional to the evoked torque. The progressive increase in torque (extra torque) that may develop in response to low intensity wide-pulse high-frequency (WPHF) NMES holds great promise for rehabilitation as it overcomes the main limitation of NMES, namely discomfort. WPHF NMES extra torque is thought to result from reflexively recruited motor units at the spinal level. However, whether WPHF NMES evoked force can be modulated is unknown. Therefore, we examined the effect of two interventions known to change the state of spinal circuitry in opposite ways on evoked torque and motor unit recruitment by WPHF NMES. The interventions were high-frequency transcutaneous electrical nerve stimulation (TENS) and anodal transcutaneous spinal direct current stimulation (tsDCS). We show that TENS performed before a bout of WPHF NMES results in lower evoked torque (median change in torque time-integral: − 56%) indicating that WPHF NMES-evoked torque might be modulated. In contrast, the anodal tsDCS protocol used had no effect on any measured parameter. Our results demonstrate that WPHF NMES extra torque can be modulated and although the TENS intervention blunted extra torque production, the finding that central contribution to WPHF NMES-evoked torques can be modulated opens new avenues for designing interventions to enhance WPHF NMES.

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