The transmission of impulses in the ectodermal slow conduction system of the sea anemone Calliactis parasitica (Couch)

1975 ◽  
Vol 62 (2) ◽  
pp. 421-432
Author(s):  
G. A. Shelton
Keyword(s):  
Electrical Stimulation ◽  
Computer Model ◽  
Pulse Amplitude ◽  
Local System ◽  
Conduction System ◽  
Repetitive Stimulation ◽  
Conduction Delay ◽  
Slow Conduction ◽  
Calliactis Parasitica ◽  
Repetitive Electrical Stimulation

1. The SS 1 fatigues in response to repetitive electrical stimulation. This fatigue is manifested by an increased conduction delay and a decreased SS 1 pulse amplitude. 2. Continued repetitive stimulation leads to the failure of the system. Recovery may take many seconds. Narrow strips of column fail more rapidly than wide strips. 3. The increased conduction delay is explained in terms of a decrease in the population of spiking cells. 4. A computer model is described and analysed. It suggests that conduction between electrically coupled ectoderm cells could be the basis for the SS1. The SS 1 may have properties not so far experimentally demonstrated; for example, under certain conditions it could behave as a local system.

scholarly journals Co-Ordination of Pedal-Disk Detachment in the Sea Anemone Calliactis Parasitica

1969 ◽  
Vol 51 (2) ◽  
pp. 387-396
Author(s):  
I. D. MCFARLANE
Keyword(s):  
Electrical Stimulation ◽  
Electrical Activity ◽  
Mechanical Stimulation ◽  
Average Frequency ◽  
Conduction System ◽  
Identical Stimulus ◽  
Slow Conduction ◽  
Calliactis Parasitica ◽  
Behavioural Sequence ◽  
Stimulation Of

1. Electrical activity has been recorded from the sphincter region of Calliactis parasitica during the behavioural sequence in which the anemone detaches from the substrate and attaches to a Buccinum shell. The ectodermal slow-conduction system (SS1) fires repetitively, the majority of observed pulses occurring in the period prior to detachment (a typical example is 25 SS1pulses at an average frequency of 1 pulse/7 sec.). Shell-tentacle contact is essential for stimulation of SS1activity. 2. Mechanical stimulation of the column excites the SS1, and 30 stimuli at a frequency of about one shock/5 sec. give pedal disk detachment. 3. Electrical stimulation of the ectoderm excites the SS1and about 30 stimuli at frequencies between one shock/3 sec. and one shock/9 sec. produce detachment. Detachment and the SS1 have an identical stimulus threshold. It is concluded that detachment is co-ordinated by the SS1.

Two Slow Conduction Systems in the Sea Anemone Calliactis Parasitica

1969 ◽  
Vol 51 (2) ◽  
pp. 377-385 ◽  
Author(s):  
I. D. MCFARLANE
Keyword(s):  
Electrical Activity ◽  
Conduction Velocity ◽  
Conduction System ◽  
Repetitive Stimulation ◽  
Sea Anemone ◽  
Response Delay ◽  
The Third ◽  
Slow Conduction ◽  
Calliactis Parasitica ◽  
Oral Disk

1. Suction electrodes record electrical activity associated with three conduction systems in the sea anemone Calliactis parasitica. The two slow systems (SS1 and SS2) are previously undescribed. The third system is the through-conduction system. 2. Evidence is given that the SS1 and SS2 are located in the ectoderm and endoderm respectively. The conductile elements have not been identified. 3. The conduction velocity of the SS1 is 4.4-14.6 cm./sec. at 11° C. and is highest in the oral disk. The SS2 velocity is 3.0-5.3 cm./sec. 4. Both slow systems show a marked increase in response delay on repetitive stimulation and fail at stimulation frequencies higher than one shock/3 sec.

Control of Preparatory Feeding Behaviour in the Sea Anemone Tealia Felina

1970 ◽  
Vol 53 (1) ◽  
pp. 211-220
Author(s):  
I. D. McFARLANE
Keyword(s):  
Electrical Stimulation ◽  
Feeding Behaviour ◽  
Mouth Opening ◽  
Conduction System ◽  
Sea Anemone ◽  
Feeding Response ◽  
Slow Conduction ◽  
Oral Disk ◽  
Stimulation Of

1. Dissolved food substances elicit preparatory feeding behaviour in the sea anemone Tealia felina. This behaviour takes the form of expansion of the oral disk and lowering of the margin of the disk. Food may also cause mouth opening and pharynx protrusion. This pre-feeding response may increase the chance of food capture. 2. The expansion and lowering of the oral disk can also be elicited by electrical stimulation of a slow conduction system, the SS1, thought to be located in the ectoderm. 3. SS1 activity is seen when the anemone is exposed to dissolved food substances. 4. It is concluded that preparatory feeding behaviour in Tealia is mediated in part by the SS1.

Control of the Pacemaker System of the Nervenet in the Sea Anemone Calliactis Parasitica

1974 ◽  
Vol 61 (1) ◽  
pp. 129-143
Author(s):  
I. D. MCFARLANE
Keyword(s):  
Sensory Feedback ◽  
Pulse Frequency ◽  
Pulse Number ◽  
Pulse Action ◽  
Conduction System ◽  
The Body ◽  
Optimum Frequency ◽  
Nerve Net ◽  
Slow Conduction ◽  
Calliactis Parasitica

1. The rhythm of spontaneous nerve-net pulses is reset by intercalated evoked nerve-net pulses. 2. The origin of spontaneous nerve-net pulses can shift during a burst. There seem to be many potential pacemakers, widely distributed throughout the body, but apparently absent from the tentacles. 3. If a spontaneous or evoked pulse in the endodermal slow conduction system (SS 2) occurs during a burst, the nerve-net pulse intervals are increased during a 15-30 sec period following the SS 2 pulse. Additional SS 2 pulses cause a further increase in pulse intervals. 4. Nerve-net bursts are followed by a sequence of muscular contractions. The size of the contraction shown by any muscle group depends on nerve-net pulse number and frequency, the optimum frequency being different for different muscles. It is suggested that the SS 2 pulse action on nerve-net pulse frequency can significantly alter the behavioural output of nerve-net bursts. The SS 2 activity may represent sensory feedback on to the nervous pacemakers.

Control of shell settling in the swimming sea anemone Stomphia coccinea

1976 ◽  
Vol 64 (2) ◽  
pp. 419-429
Author(s):  
I. D. Lawn
Keyword(s):  
Electrical Stimulation ◽  
Electrical Activity ◽  
Complete Response ◽  
Conduction System ◽  
Sea Anemone ◽  
Interpulse Interval ◽  
Slow Conduction ◽  
Behavioural Sequence ◽  
Pedal Disc ◽  
Stimulation Of

1. Electrical activity has been recorded from Stomphia coccinea during the behavioural sequence in which the detached anemone settles on to a Modiolus shell. 2. When a responsive tentacle contacts the shell, a short, complex burst of pulses is elicited. These remain confined to the region of contact. The endodermal slow-conduction system (SS2) then begins to fire repetitively (a typical example is 16 SS2 pulses at a mean interpulse interval of 5 s) until the pedal disc begins to inflate. Shell-tentacle contact is essential for stimulation of SS2 activity. 3. The complete response, apart from local bending of the column, may be reproduced by electrical stimulation of the SS2 alone. As few as 10 stimuli at frequencies between 1 shock/s and 1 shock/10 s are required to elicit the response.

Two slow conduction systems co-ordinate shell-climbing behaviour in the sea anemone Calliactis parasitica

1976 ◽  
Vol 64 (2) ◽  
pp. 431-445
Author(s):  
I. D. McFarlane
Keyword(s):  
Electrical Stimulation ◽  
Low Frequency ◽  
Sensory Response ◽  
Pulse Interval ◽  
Nerve Net ◽  
Slow Conduction ◽  
Calliactis Parasitica ◽  
Climbing Behaviour ◽  
The Mean ◽  
Stimulation Of

1. Pulses in two slow conducting systems, the ectodermal SS 1 and the endodermal SS 2, were recorded during shell-climbing behaviour. The mean pulse interval of SS 1 pulses was 7–4 s and that of SS 2 pulses was 6-4 s. Activity in both systems may arise as a sensory response of tentacles to shell contact, but the SS 1 and SS 2 may not share the same receptors. 2. Electrical stimulation of the SS 1 and SS 2 together, at a frequency of 1 shock every 5 s, elicits shell-climbing behaviour in the absence of a shell. 3. Low-frequency nerve-net activity (about 1 pulse every 15 s) accompanies column bending during both normal and electrically elicited responses. This activity probably arises as a result of column bending and is not due to a sensory response to the shell.

scholarly journals Nerve Nets and Conducting Systems in Sea Anemones: Two Pathways Excite Tentacle Contractions in Calliactis Parasitica

1984 ◽  
Vol 108 (1) ◽  
pp. 137-149
Author(s):  
IAN D. MCFARLANE
Keyword(s):  
Electrical Activity ◽  
Conduction System ◽  
Sea Anemones ◽  
Single Shock ◽  
Nerve Net ◽  
Slow Conduction ◽  
Calliactis Parasitica ◽  
Slight Movement ◽  
Pulse Stimulation ◽  
Stimulation Of

1. Single shocks to the column sometimes evoke tentacle contractions, ranging from slight movement of a few scattered tentacles to rapid bending or shortening of all the tentacles. Some individuals are more responsive than others. Complex bursts of electrical activity follow single shocks, but only in tentacles that contract. 2. These single shocks excite pulses in two conducting systems - the through-conducting nerve net (TCNN) and the ectodermal slow conduction system (SSI). When a single shock evokes contractions and bursts of electrical activity, these usually follow the SSI pulse, rarely the TCNN pulse. Stimulation of the SSI alone causes tentacle contraction in responsive anemones. 3. Fast tentacle contractions always follow the second of two closelyspaced TCNN pulses: the TCNN shows facilitation (Pantin, 1935a). An SSI pulse, however, does not facilitate subsequent pulses in either the SSI or TCNN. 4. There are two pathways for activation of tentacle contractions. The TCNN pathway is mechano-sensitive and normally requires facilitation. The SSI pathway is mechano- and chemosensitive, only requires a single SSI pulse to evoke contraction, but is very labile. It is proposed that the TCNN and the SSI do not excite the ectodermal muscles directly, but via a multipolar nerve net.

Electrophysiology of two parallel conducting systems in the colonial Hexacorallia

1976 ◽  
Vol 193 (1110) ◽  
pp. 77-87 ◽  
Keyword(s):  
Electrical Activity ◽  
Refractory Period ◽  
Feeding Behaviour ◽  
Conduction System ◽  
Mechanical Stimuli ◽  
Nerve Net ◽  
Slow Conduction ◽  
Calliactis Parasitica ◽  
Oral Disk ◽  
Dendrogyra Cylindrus

Extracellular polythene suction electrodes have been used to record electrical activity in four species of Madreporaria - Dendrogyra cylindrus, Meandrina meandrites, Mussa angulosa and Eusmilia fastigiata . A colonial conduction system, believed to be the nerve net, was found in all species. It conducted without decrement between all polyps. A second colonial system was found in Meandrina, Mussa and Eusmilia . Pulses could be recorded only from tentacles or oral disks though the system could be excited by electrical or mechanical stimuli to any part of the colony. In the tentacles and oral disk, this conduction system had a refractory period of about 60 ms while in the column or interpolyp regions the refractory period was much longer - up to several seconds. The effect of these differences was to limit the frequency of conduction of pulses in this system between polyps. The second system is compared to the s. s. 1 (ectodermal slow conduction system) of the sea anemone Calliactis parasitica . It is the first demonstrated example of a colonial slow conduction system in the Hexacorallia and is similar in properties to a colonial slow conduction system previously described for Pennatula phosphorea (Octocorallia). The slow conduction system may have a rôle during feeding behaviour by promoting expansion of tentacles and the production of mucus.

Repetitive Potentials Following Brief Electric Stimuli in a Hydroid

1961 ◽  
Vol 38 (3) ◽  
pp. 579-593
Author(s):  
ROBERT K. JOSEPHSON
Keyword(s):  
Electrical Stimulation ◽  
Average Velocity ◽  
Nervous Activity ◽  
Repetitive Stimulation ◽  
Conducting System ◽  
Threshold Intensity ◽  
Electric Shocks ◽  
Electrical Pulses ◽  
Minimum Interval ◽  
Shape And Size

1. Electrical pulses (amplitude -0.05 to -15 mV.; duration 20-120 msec.) have been recorded from the stolon of Cordylophora lacustris following stimulation. These pulses are propagated with an average velocity of 2.7 cm./sec. at 22° C. 2. Brief electric shocks of little more than threshold intensity can evoke bursts of pulses. The number of pulses in a burst increases with stimulus intensity, but the shape and size of individual pulses do not. 3. Repetitive stimulation causes facilitation of both size of single pulses and number of pulses in a burst. Refractory period, if present, is variable. The minimum interval between two pulses is about 200 msec. 4. Mechanical stimulation evokes pulses identical to those evoked by electrical stimulation. 5. The greater the number of pulses recorded in the stolon near a polyp, the greater and faster is the contraction of that polyp. 6. The number of pulses, but not their individual sizes, decreases with increasing distance from the point of stimulation. 7. It is concluded that conduction in the stolon and the electrical pulses are due to nervous activity and that the conducting system is a network having interneural junctions which sometimes require to be facilitated.

scholarly journals Natural Sensations Evoked in Distal Extremities Using Surface Electrical Stimulation

2018 ◽  
Vol 12 (1) ◽  
pp. 1-15 ◽  
Author(s):  
Julia P. Slopsema ◽  
John M. Boss ◽  
Lane A. Heyboer ◽  
Carson M. Tobias ◽  
Brooke P. Draggoo ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Low Frequency ◽  
Pulse Amplitude ◽  
Neural Stimulation ◽  
Phantom Limb ◽  
Neural Function ◽  
Medical Treatments ◽  
Non Invasive ◽  
Knee Strength ◽  
Better Than

Background: Electrical stimulation is increasingly relevant in a variety of medical treatments. In this study, surface electrical stimulation was evaluated as a method to non-invasively target a neural function, specifically natural sensation in the distal limbs. Method: Electrodes were placed over the median and ulnar nerves at the elbow and the common peroneal and lateral sural cutaneous nerves at the knee. Strength-duration curves for sensation were compared between nerves. The location, modality, and intensity of each sensation were also analyzed. In an effort to evoke natural sensations, several patterned waveforms were evaluated. Results: Distal sensation was obtained in all but one of the 48 nerves tested in able-bodied subjects and in the two nerves from subjects with an amputation. Increasing the pulse amplitude of the stimulus caused an increase in the area and magnitude of the sensation in a majority of subjects. A low frequency waveform evoked a tapping or tapping-like sensation in 29 out of the 31 able-bodied subjects and a sensation that could be considered natural in two subjects with an amputation. This waveform performed better than other patterned waveforms that had proven effective during implanted extra-neural stimulation. Conclusion: Surface electrical stimulation has the potential to be a powerful, non-invasive tool for activation of the nervous system. These results suggest that a tapping sensation in the distal extremity can be evoked in most able-bodied individuals and that targeting the nerve trunk from the surface is a valid method to evoke sensation in the phantom limb of individuals with an amputation for short term applications.

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