Electrical Activity in the Radial Nerve Cord And Ampullae of Sea Urchins

1965 ◽  
Vol 43 (2) ◽  
pp. 247-256
Author(s):  
D. C. SANDEMAN
Keyword(s):  
Electrical Activity ◽  
Nerve Cord ◽  
Action Potentials ◽  
Radial Nerve ◽  
Sea Urchins ◽  
Side Branch ◽  
Single Shock ◽  
Lateral Branches ◽  
Tube Feet ◽  
Stimulation Of

1. A single shock applied through wick electrodes to the isolated radial nerve cord of a sea urchin produces a recordable potential in the cord. The potential is conducted along the cord at a velocity of between 14 and 20 cm./sec. 2. The potential is complex and graded. Two components of the potential can be identified and have different thresholds to stimulation, conduction velocities and amplitudes. They are believed to represent two classes of fibres. 3. The potential is conducted decrementally along the cord and normally cannot be recorded at distances greater than 6o mm. from the stimulus. The amplitude of the potential decays logarithmically falling to half after 7 mm. spread. There is no facilitation of amplitude or distance of spread. 4. Potentials initiated simultaneously at either end of the isolated nerve cord collide and partially occlude each other. 5. Stimulation of a side branch of the nerve cord evokes potentials recordable from only ipsilateral neighbouring side branches and the whole cord. However, contractions of the contralateral ampullae following stimulation of lateral branches reveal spread of the excitation beyond the region of recordable potentials. 6. A single shock to a cord still attached to the test causes contraction of the associated ampullae. One ampulla will contract several times after a single shock, a period of relaxation following each contraction. 7. Electrical activity recorded from the ampullae, and lasting many seconds after the single shock, corresponds with their contractions. The activity is believed to be muscle action potentials. 8. Evidence of a feedback from damaged tube feet to the cord, suppressing ampulla response to cord stimulation, was found.

The Electrical Activity of the Radial Nerve in Diadema antillarum Philippi and Certain Other Echinoids

1968 ◽  
Vol 48 (2) ◽  
pp. 279-289
Author(s):  
N. MILLOTT ◽  
H. OKUMURA
Keyword(s):  
Electrical Activity ◽  
Conduction Velocity ◽  
Radial Nerve ◽  
Diadema Antillarum ◽  
Double Peak ◽  
Slow Potential ◽  
Refractory Periods ◽  
Spine Movement ◽  
Stimulation Of

1. The propagated massed potentials which follow stimulation of the radial nerve in Arbacia, Diadema, Echinus and Paracentrotus are described. 2. Approximate values for the averaged absolute and relative refractory periods and the conduction velocity were obtained. 3. The response of Diadema has a double peak which is shown to represent responses of nerves differing in excitability and conduction velocity. The fast potential is concerned with spine movement. The slow potential is related to inhibition of spine movements excited photically.

Electrical activity of the isolated nerve-urinary bladder strip preparation of the rabbit

1961 ◽  
Vol 201 (3) ◽  
pp. 408-412 ◽  
Author(s):  
R. C. Ursillo
Keyword(s):  
Electrical Activity ◽  
Single Cells ◽  
Slow Waves ◽  
Glass Capillary ◽  
Pelvic Nerve ◽  
Single Shock ◽  
Bladder Strip ◽  
Whole Muscle ◽  
Dominant Activity ◽  
Stimulation Of

The electrical activity of single cells of the smooth muscle of the isolated pelvic nerve-bladder strip preparation of the rabbit has been recorded by means of KCl-filled glass capillary microelectrodes. It was found that increasing the tension on the muscle either by stretching or by the addition of carbachol (3 µg/ml) to the bathing fluid causes a concomitant depolarization of the cell membrane. Spontaneous electrical activity and that elicited by stimulation of the nerve were similar and consisted of slow waves of depolarization of a 3–5 sec duration and spikes superimposed upon the depolarization phase of the slow wave. The spikes varied from 5 to 35 mv with no overshoot. Excitability of cells varied from one in which no response to tetanic stimulation of the nerve was seen to one which exhibited a series of spikes to a single shock. It was shown that slow waves and spikes could occur out of phase with the dominant activity of the whole muscle. Latency to a single shock to the nerve was found to be quite consistent for the same cell. However, a marked variation in latency was found among different cells of the same preparation.

Emergence of Radial Nerve Dominance in Median Nerve Cortex After Median Nerve Transection in an Adult Squirrel Monkey

1997 ◽  
Vol 77 (1) ◽  
pp. 522-526 ◽  
Author(s):  
C. E. Schroeder ◽  
S. Seto ◽  
P. E. Garraghty
Keyword(s):  
Median Nerve ◽  
Squirrel Monkey ◽  
Ulnar Nerve ◽  
Action Potentials ◽  
Radial Nerve ◽  
Current Source ◽  
Short Latency ◽  
Nerve Transection ◽  
A Site ◽  
Stimulation Of

Schroeder, C. E., S. Seto, and P. E. Garraghty. Emergence of radial nerve dominance in median nerve cortex after median nerve transection in an adult squirrel monkey. J. Neurophysiol. 77: 522–526, 1997. Throughout the glabrous representation in Area 3b, electrical stimulation of the dominant (median or ulnar) input produces robust, short-latency excitation, evident as a net extracellular “sink” in the Lamina 4 current source density (CSD) accompanied by action potentials. Stimulation of the collocated nondominant (radial nerve) input produces a subtle short-latency response in the Lamina 4 CSD unaccompanied by action potentials and followed by a clear excitatory response 12–15 ms later. Laminar response profiles for both inputs have a “feedforward” pattern, with initial activation in Lamina 4, followed by extragranular laminae. Such corepresentation of nondominant radial nerve inputs with the dominant (median or ulnar nerve) inputs in the glabrous hand surface representation provides a likely mechanism for reorganization after median nerve section in adult primates. To investigate this, we conducted repeated recordings using an implanted linear multi-electrode array straddling the cortical laminae at a site in “median nerve cortex” (i.e., at a site with a cutaneous receptive field on the volar surface of D2 and thus with its dominant afferent input conveyed by the median nerve) in an adult squirrel monkey. We characterized the baseline responses to median, radial, and ulnar nerve stimulation. We then cut the median nerve and semi-chronically monitored radial nerve, ulnar nerve and median nerve (proximal stump) evoked responses. The radial nerve response in median nerve cortex changed progressively during the weeks after median nerve transection, ultimately assuming the characteristics of the dominant nerve profile. During this time, median, and ulnar nerve profiles displayed little or no change.

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.

ACTIVATION OF HYPOTHALAMIC NEURONAL ACTIVITY BY THE ELECTROLYTIC DEPOSITION OF IRON INTO THE PREOPTIC AREA

1978 ◽  
Vol 79 (1) ◽  
pp. 107-NP ◽  
Author(s):  
P. VAN DER SCHOOT ◽  
D. W. LINCOLN ◽  
J. S. CLARK
Keyword(s):  
Electrical Activity ◽  
Action Potentials ◽  
Preoptic Area ◽  
Slow Wave Sleep ◽  
Platinum Electrode ◽  
Electrophysiological Recording ◽  
Electrolytic Deposition ◽  
Steel Electrode ◽  
Electrolytic Lesions ◽  
Stimulation Of

Changes in brain activity after electrochemical stimulation of the preoptic area of prooestrous rats were studied by the measurement of the electro-encephalogram (EEG) of the frontal cortex and the recording of single neurones in the anterior hypothalamus. All rats were anaesthetized with urethane between 10.00 and 12.00 h to allow prolonged electrophysiological recording and to block the spontaneous surge of LH during the afternoon. Electrochemical stimulation was applied, between 12.00 and 14.00 h, as an anodal current through an implanted steel electrode; this caused the electrolytic deposition of iron and evoked the release of LH and ovulation. Electrochemical stimulation of the preoptic area changed the cortical EEG, either immediately or after a delay of a few minutes, from a labile pattern with alternate periods of arousal and slow-wave sleep, to a stage of continuous arousal which persisted for the remainder of the recording period (2–3 h). Conversely, the EEG pattern of the cortex was not disturbed by electrolytic lesions placed in the preoptic area through a platinum electrode. Electrochemical stimulation of the arcuate region of the hypothalamus, the lateral septal area, the medial amygdaloid complex and the anterior parts of the thalamus caused no obvious change in the EEG patterns. Ipsilateral anterior hypothalamic neurones, about 1 mm caudal to the focus of electrochemical stimulation, displayed an immediate decrease in electrical activity after application of the current. After 10–20 min however, the rates of discharge of action potentials in 9 out of the 16 neurones under consideration increased progressively from 0·5 to 15–25 action potentials/s and these rates were maintained until the recordings were lost after 90–230 min. No such acceleration in electrical activity was observed in neurones on the contralateral side. Iron deposited during electrochemical stimulation was precipitated as sulphide and stained by Timm's method. There was a central damaged area of radius 0·6 mm surrounded by an 'undamaged' area with considerable infiltration of iron, up to a distance of 1·7 mm from the electrode tip. Cells within the area of infiltration did not stain for iron 10 min after electrochemical stimulation, but after 30 min, neural elements in this peripheral zone were stained in a manner similar to the Golgi method. The concentrations of LH in the plasma remained unchanged in all rats for 10–15 min after electrochemical stimulation. Thereafter, the concentrations increased progressively and approximately in parallel to the changes in action potential activity until, after 2 h, the individual concentrations of 300–600 ng LH/ml were more than six times the values obtained before stimulation. Bilateral electrochemical stimulation resulted in appreciably higher concentrations of LH and produced values close to those observed during the pro-oestrous surge of the hormone. Electrochemical stimulation during the afternoon of the day before pro-oestrus consistently advanced ovulation; this response occurred irrespective of whether the resultant lesions were large or small. The production of a large lesion during the afternoon of the day before pro-oestrus without concomitant deposition of iron by the use of a platinum electrode appeared to block the surge of LH on the subsequent day and the preovulatory follicles became atretic. These results suggest that the ovulatory response to electrochemical stimulation is related primarily to an increase in the electrical activity of the hypothalamus and not to the destruction of brain tissue.

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.

Some Preliminary Observations on the Effects of Cations on Conduction Processes in the Abdominal Nerve Cord of the Stick Insect, Carausius Morosus

1965 ◽  
Vol 42 (1) ◽  
pp. 1-6
Author(s):  
J. E. TREHERNE
Keyword(s):  
Electrical Stimulation ◽  
Nerve Conduction ◽  
Nerve Cord ◽  
Action Potentials ◽  
Ionic Composition ◽  
Stick Insect ◽  
Carausius Morosus ◽  
Stimulation Of

1. In the haemolymph of the stick insect Carausius morosus the concentration of potassium exceeds that of sodium and the concentration of magnesium exceeds that of calcium. The implications of this situation for nerve conduction have been studied. 2. Conduction is maintained in intact and desheathed preparations of the fourth adbominal ganglion under irrigation with a solution resembling haemolymph in ionic composition. 3. Action potentials recorded in response to electrical stimulation of the nerve cord decline in sodium-free solutions, both in intact and in desheathed preparations. 4. Conduction declines slowly under irrigation with magnesium-free solutions both in intact and in desheathed preparations.

scholarly journals Adrenaline Stimulates Glucagon Secretion in Pancreatic A-Cells by Increasing the Ca2+ Current and the Number of Granules Close to the L-Type Ca2+ Channels

1997 ◽  
Vol 110 (3) ◽  
pp. 217-228 ◽  
Author(s):  
Jesper Gromada ◽  
Krister Bokvist ◽  
Wei-Guang Ding ◽  
Sebastian Barg ◽  
Karsten Buschard ◽  
...  
Keyword(s):  
Electrical Activity ◽  
Adrenergic Receptors ◽  
Action Potentials ◽  
Glucagon Secretion ◽  
Stimulatory Action ◽  
Voltage Gated ◽  
A Cells ◽  
Β Adrenergic Receptors ◽  
Ca2 Channels ◽  
Stimulation Of

We have monitored electrical activity, voltage-gated Ca2+ currents, and exocytosis in single rat glucagon-secreting pancreatic A-cells. The A-cells were electrically excitable and generated spontaneous Na+- and Ca2+-dependent action potentials. Under basal conditions, exocytosis was tightly linked to Ca2+ influx through ω-conotoxin-GVIA–sensitive (N-type) Ca2+ channels. Stimulation of the A-cells with adrenaline (via β-adrenergic receptors) or forskolin produced a greater than fourfold PKA-dependent potentiation of depolarization-evoked exocytosis. This enhancement of exocytosis was due to a 50% enhancement of Ca2+ influx through L-type Ca2+ channels, an effect that accounted for <30% of the total stimulatory action. The remaining 70% of the stimulation was attributable to an acceleration of granule mobilization resulting in a fivefold increase in the number of readily releasable granules near the L-type Ca2+ channels.

scholarly journals Mobilization of a Coordinated Escape Response by Giant Axons in the Ophiuroid, Ophiopteris Papillosa

1987 ◽  
Vol 128 (1) ◽  
pp. 287-305
Author(s):  
AUDREY YEE ◽  
JAMES BURKHARDT ◽  
W. F. GILLY
Keyword(s):  
Electrical Activity ◽  
Action Potentials ◽  
Escape Response ◽  
Small Amplitude ◽  
Free Medium ◽  
Mean Velocity ◽  
Giant Axons ◽  
Sequential Activation ◽  
The One ◽  
Stimulation Of

1. The escape response of Ophiopteris papillosa to contact by a predatory asteroid consists of a fast withdrawal of the stimulated arm, completed in less than 1 s, followed by rapid locomotion carried out by coordinated rowing of the two arms opposite the one stimulated. 2. Electrical activity recorded from the radial nerve cord (RNC) during the locomotory phase consists of small-amplitude spikes (<5 μV). 3. The initial arm jerk response is mediated by sequential activation of segmental intervertebral muscles, and the onset of activation progresses centrally at a rate of < 10cms−1 commencing 100–200ms after stimulation. 4. Electrical activity recorded from the RNC immediately after tubefoot stimulation consists of a burst of large-amplitude spikes (50–100 μV) that propagate centrally at approximately 50cms−1. 5. Electrical activity in the RNC with the lowest threshold to direct electrical stimulation consists of large spikes propagating at a mean velocity of 55 cms−1 at 13°C, and this activity persists in a Ca2--free medium. 6. Electrical and tubefoot stimulation of the arm tip in the same preparation both trigger a burst of large action potentials that propagate at approximately 50cms−1. 7. The identity of the giant axons activated by tubefoot stimulation, the pathways they follow and their role in mobilizing the coordinated escape response are discussed. Note: To whom reprint requests should be sent.

scholarly journals The Effects of Curare in the Cockroach

1970 ◽  
Vol 52 (3) ◽  
pp. 593-601
Author(s):  
K. J. FRIEDMAN ◽  
A. D. CARLSON
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Electrical Stimulation ◽  
Action Potential ◽  
Nerve Cord ◽  
Action Potentials ◽  
Periplaneta Americana ◽  
Sensory Motor ◽  
Giant Fibres ◽  
Stimulation Of

1. The study of insect curarization in the cockroach, Periplaneta americana, has been continued. The application of curare solution (0.032 M dTC) to the nerve cord produced blockage of action-potential conduction in the giant fibres lying within the nerve cord. 2. The application of curare solution to the cerci prevented the recording of action potentials from the cercal nerves of the organism. Application of dTC to the cercal nerve-A6 region of the cockroach prevented giant fibres from responding to electrical stimulation of the cercal nerves. These results are interpreted as indicating that curare blocks the conduction of action potentials in the cercal nerve. 3. It is proposed that curare can induce blockage of conduction in sensory, motor and central nervous system fibres. It is further proposed that this blockage of conduction is the mechanism of insect curarization. 4. The results of previous reports concerned with insect curarization are re-interpreted in view of the proposal. Several of the conflicts in these reports are resolved by the proposal that blockage of conduction is the mechanism of insect curarization.

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