Slow Activity in the Nervous System of the Earthworm, Lumbricus Terrestris

1967 ◽  
Vol 46 (3) ◽  
pp. 571-583
Author(s):  
M. B. V. ROBERTS
Keyword(s):  
Nervous System ◽  
Nerve Cord ◽  
Action Potentials ◽  
Longitudinal Muscle ◽  
Lumbricus Terrestris ◽  
Longitudinal Contraction ◽  
Peripheral Stimulation ◽  
Segmental Nerve ◽  
Slow Potentials ◽  
Slow Activity

1. Three thresholds are demonstrated in the first segmental nerve and two (sometimes three) in the second and third segmental nerves together. 2. Slow potentials recorded from the ventral nerve cord consist of several peaks. The first peak is composed of three spikes which make their appearance at different thresholds. Transmission of at least some of the slow potentials is decremental. 3. Transmission speeds in the nerve cord and segmental nerves range from 0.4 to 0.6 m./sec. 4. Action potentials in the longitudinal muscle are recorded in response to slow potentials in the nerve cord. 5. Two slow reflexes, one involving elongation, the other longitudinal contraction, are described. The latter has the lower threshold with peripheral stimulation. 6. Slow activity in the nervous system is discussed in relation to reflex activity of the earthworm and the neurone anatomy of the nerve cord and segmental nerves.

Neuromuscular Physiology of the Longitudinal Muscle of the Earthworm, Lumbricus Terrestris

1974 ◽  
Vol 60 (2) ◽  
pp. 453-467
Author(s):  
C. D. DREWES ◽  
R. A. PAX
Keyword(s):  
Time Course ◽  
Longitudinal Muscle ◽  
Lumbricus Terrestris ◽  
Single Pulse ◽  
Repetitive Stimulation ◽  
Muscle Fibres ◽  
Mechanical Responses ◽  
Segmental Nerve ◽  
Earthworm Lumbricus ◽  
Stimulation Of

1. Patterns of innervation of the longitudinal muscle of the earthworm, Lumbricus terrestris, were examined electrophysiologically. 2. The longitudinal musculature of a segment is innervated by relatively few axons, a fast and slow axon being present in segmental nerve I and in the double nerve, segmental nerve II-III. 3. Single-pulse stimulation of the fast axon produces large external muscle potentials and small twitch-like contractions, which with repetitive stimulation are antifacilitating. 4. Repetitive stimulation of the slow axon produces large, slowly developing and sustained mechanical responses, with electrical and mechanical responses showing summation and facilitation. 5. The amplitude and time course of slow mechanical responses are related to the frequency of stimulation. 6. Individual longitudinal muscle fibres are innervated by either the fast or slow axon in a segmental nerve, or by both fast and slow axons. 7. No evidence was found for peripheral inhibitory innervation of the longitudinal muscle.

Mechanical responses of the body wall muscle of the earthworm, Lumbricus terrestris, to segmental nerve stimulation

1971 ◽  
Vol 49 (12) ◽  
pp. 1527-1534 ◽  
Author(s):  
Charles D. Drewes ◽  
Ralph A. Pax
Keyword(s):  
Nerve Stimulation ◽  
Longitudinal Muscle ◽  
Circular Muscle ◽  
Lumbricus Terrestris ◽  
Repetitive Stimulation ◽  
Second Phase ◽  
Muscle Response ◽  
Mechanical Responses ◽  
Segmental Nerve ◽  
Earthworm Lumbricus

Suitable nerve–muscle preparations are described for recording the electrical and mechanical responses of the longitudinal and circular muscle to segmental nerve stimulation in the earthworm, Lumbricus terrestris. The longitudinal muscle response to prolonged repetitive stimulation consists of a smooth increase in tension to form a peak in less than 10 s followed by a slow decline in tension to about one-half peak tension in 45 s. The circular muscle response to prolonged repetitive stimulation consists of two distinct phases of tension development: an initial, rapidly developing peak resembling that in longitudinal muscle and a slow, irregularly developing second phase. The circular and longitudinal muscle responses are obtained at frequencies above f or 2/s, with the amplitude of each response being a function of the stimulus strength within a range of 0.4–1.4 V (2 ms) and the stimulus frequency within a range of 5–50/s. In addition there is a threshold-dependent inhibition of the second phase of the circular muscle response.Circular and longitudinal responses to single stimuli are obtained with stimulus strengths approximately 10 times greater than those of the responses to repetitive stimulation and the amplitude of these responses appears to be a function of the strength of stimulation. The single stimulus response appears to be a result of repetitive firing in the same motor fibers which mediate the response to repetitive stimulation.

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.

scholarly journals Proclivity of nervous system preservation in Cambrian Burgess Shale-type deposits

2019 ◽  
Vol 286 (1917) ◽  
pp. 20192370 ◽  
Author(s):  
Javier Ortega-Hernández ◽  
Rudy Lerosey-Aubril ◽  
Stephen Pates
Keyword(s):  
Nervous System ◽  
Great Basin ◽  
South China ◽  
Nerve Cord ◽  
Original Description ◽  
The Body ◽  
Burgess Shale ◽  
Microbial Biofilms ◽  
Segmental Nerve ◽  
Spatio Temporal

Recent investigations on neurological tissues preserved in Cambrian fossils have clarified the phylogenetic affinities and head segmentation in pivotal members of stem-group Euarthropoda. However, palaeoneuroanatomical features are often incomplete or described from single exceptional specimens, raising concerns about the morphological interpretation of fossilized neurological structures and their significance for early euarthropod evolution. Here, we describe the central nervous system (CNS) of the short great-appendage euarthropod Alalcomenaeus based on material from two Cambrian Burgess Shale-type deposits of the American Great Basin, the Pioche Formation (Stage 4) and the Marjum Formation (Drumian). The specimens reveal complementary ventral and lateral views of the CNS, preserved as a dark carbonaceous compression throughout the body. The head features a dorsal brain connected to four stalked ventral eyes, and four pairs of segmental nerves. The first to seventh trunk tergites overlie a ventral nerve cord with seven ganglia, each associated with paired sets of segmental nerve bundles. Posteriorly, the nerve cord features elongate thread-like connectives. The Great Basin fossils strengthen the original description—and broader evolutionary implications—of the CNS in Alalcomenaeus from the early Cambrian (Stage 3) Chengjiang deposit of South China. The spatio-temporal recurrence of fossilized neural tissues in Cambrian Konservat-Lagerstätten across North America (Pioche, Burgess Shale, Marjum) and South China (Chengjiang, Xiaoshiba) indicates that their preservation is consistent with the mechanism of Burgess Shale-type fossilization, without the need to invoke alternative taphonomic pathways or the presence of microbial biofilms.

Electrical Properties and Anion Permeability of Doubly Rectifying Junctions in the Leech Central Nervous System

1988 ◽  
Vol 137 (1) ◽  
pp. 1-11
Author(s):  
Susan E. Acklin
Keyword(s):  
Central Nervous System ◽  
T Cells ◽  
Nervous System ◽  
T Cell ◽  
Action Potentials ◽  
Sodium Pump ◽  
Current Flow ◽  
Cell Movement ◽  
Voltage Dependent ◽  
Electrical Connections

A study has been made of the electrical connections between touch sensory (T) neurones in the leech central nervous system (CNS) which display remarkable double rectification: depolarization spreads in both directions although hyperpolarization spreads poorly. Tests were made to determine whether this double rectification was a property of the junctions themselves or whether it resulted from changes in the length constants of processes intervening between the cell body and the junctions. Following trains of action potentials, T cells and their fine processes within the neuropile became hyperpolarized through the activity of an electrogenie sodium pump. When any T cell was hyperpolarized by 25 mV by repetitive stimulation, hyperpolarization failed to spread to the T cells to which it was electrically coupled. Further evidence for double rectification of junctions linking T cells was provided by experiments in which Cl− was injected electrophoretically. Cl− injection into one T cell caused inhibitory potentials recorded in it to become reversed. After a delay, Cl− spread to reverse IPSPs in the coupled T cell. Movement of Cl−, like current flow, was dependent on membrane potential. When the T cell into which Cl− was injected was kept hyperpolarized, Cl− failed to move into the adjacent T cell. Upon release of the hyperpolarization in the injected T cell, Cl− moved and reversed IPSPs in the coupled T cell. Together these results indicate that the gating properties of channels linking T cells are voltage-dependent, such that depolarization of either cell allows channels to open whereas hyperpolarization causes them to close.

Electrical interactions between the giant axons of a polychaete worm (Sabella penicillus L.)

1980 ◽  
Vol 84 (1) ◽  
pp. 119-136
Author(s):  
D. Mellon ◽  
J. E. Treherne ◽  
N. J. Lane ◽  
J. B. Harrison ◽  
C. K. Langley
Keyword(s):  
Safety Factor ◽  
Nerve Cord ◽  
Action Potentials ◽  
Divalent Cations ◽  
Muscular Contraction ◽  
The Body ◽  
The Other ◽  
Intracellular Recordings ◽  
Giant Axons ◽  
Other Hand

Intracellular recordings demonstrated a transfer of impulses between the paired giant axons of Sabella, apparently along narrow axonal processes contained within the paired commissures which link the nerve cords in each segment of the body. This transfer appears not to be achieved by chemical transmission, as has been previously supposed. This is indicated by the spread of depolarizing and hyperpolarizing voltage changes between the giant axons, the lack of effects of changes in the concentrations of external divalent cations on impulse transmission and by the effects of hyperpolarization in reducing the amplitude of the depolarizing potential which precedes the action potentials in the follower axon. The ten-to-one attenuation of electronic potentials between the giant axons argues against the possibility of an exclusively passive spread of potential along the axonal processes which link the axons. Observation of impulse traffic within the nerve cord commissures indicates, on the other hand, that transmission is achieved by conduction of action potentials along the axonal processes which link the giant axons. At least four pairs of intact commissures are necessary for inter-axonal transmission, the overall density of current injected at multiple sites on the follower axon being, it is presumed, sufficient to overcome the reduction in safety factor imposed by the geometry of the system in the region where axonal processes join the giant axons. The segmental transmission between the giant axons ensures effective synchronization of impulse traffic initiated in any region of the body and, thus, co-ordination of muscular contraction, during rapid withdrawal responses of the worm.

The Larval Eclosion Hormone Neurones in Manduca Sexta: Identification of the Brain-Proctodeal Neurosecretory System

1989 ◽  
Vol 147 (1) ◽  
pp. 457-470 ◽  
Author(s):  
JAMES W. TRUMAN ◽  
PHILIP F. COPENHAVER
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Manduca Sexta ◽  
Nerve Cord ◽  
Release Site ◽  
Neurosecretory System ◽  
Nerve Activity ◽  
Eclosion Hormone ◽  
The Central Nervous System ◽  
The Brain

Larval and pupal ecdyses of the moth Manduca sexta are triggered by eclosion hormone (EH) released from the ventral nervous system. The major store of EH activity in the latter resides in the proctodeal nerves that extend along the larval hindgut. At pupal ecdysis, the proctodeal nerves show a 90% depletion of stored activity, suggesting that they are the major release site for the circulating EH that causes ecdysis. Surgical experiments involving the transection of the nerve cord or removal of parts of the brain showed that the proctodeal nerve activity originates from the brain. Retrograde and anterograde cobalt fills and immunocytochemistry using antibodies against EH revealed two pairs of neurons that reside in the ventromedial region of the brain and whose axons travel ipsilaterally along the length of the central nervous system (CNS) and project into the proctodeal nerve, where they show varicose release sites. These neurons constitute a novel neuroendocrine pathway in insects which appears to be dedicated solely to the release of EH.

Neural Patterns Associated with Ventilatory Movements in Dragonfly Larvae

1970 ◽  
Vol 52 (1) ◽  
pp. 167-175
Author(s):  
P. J. MILL
Keyword(s):  
Control System ◽  
Motor Activity ◽  
Action Potentials ◽  
Motor Units ◽  
The Other ◽  
Ventilatory Control ◽  
Expiratory Phase ◽  
Segmental Nerve ◽  
Ventral Muscle ◽  
Stimulation Of

1. Rhythmic bursts of motor activity associated with the expiratory phase of ventilation have been recorded from the second lateral segmental nerves of posterior abdominal ganglia in Aeshna and Anax larvae. 2. In Aeshna the rhythmic expiratory bursts contain one, or sometimes two, motor units; whereas in Anax there are almost invariably three units. In both animals only one unit is associated with action potentials in the respiratory dorso-ventral muscle. 3. Motor activity synchronized with the expiratory bursts in the second nerves has been recorded from the other lateral nerves and from the last unpaired nerve. In addition the fifth lateral nerves carry inspiratory bursts. 4. It has been confirmed that stimulation of a first segmental nerve can re-set the ventilatory rhythm by initiating an expiratory burst in the second nerves. The original frequency is immediately resumed on cessation of stimulation. 5. The nature of the ventilatory control system in dragonfly larvae is discussed in relation to other rhythmic systems in the arthropods.

Sodium and Potassium Fluxes in the Abdominal Nerve Cord of the Cockroach, Periplaneta Americana L

1961 ◽  
Vol 38 (2) ◽  
pp. 315-322
Author(s):  
J. E. TREHERNE
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Nerve Cord ◽  
Periplaneta Americana ◽  
Unit Area ◽  
Potassium Ions ◽  
Sodium Ions ◽  
Nerve Sheath ◽  
The Central Nervous System ◽  
Sodium And Potassium

1. The influx of sodium and potassium ions into the central nervous system of Periplaneta americana has been studied by measuring the increase in radioactivity within the abdominal nerve cord following the injection of 24NA and 42K. into the haemolymph. 2. The calculated influx of sodium ions was approximately 320 mM./l. of nerve cord water/hr. and of potassium ions was 312 mM./l. of nerve cord water/hr. These values are very approximately equivalent to an influx per unit area of nerve cord surface of 13.9 x 10-2 M cm. -2 sec.-1 for sodium and 13.5 x 10-12 M cm. -2 sec.-1 for potassium ions. 3. The relatively rapid influxes of these ions are discussed in relation to the postulated function of the nerve sheath as a diffusion barrier. It is suggested that a dynamic steady state rather than a static impermeability must exist across the sheath surrounding the central nervous system in this insect.

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