Temperature Acclimation of the Functional Parameters of the Giant Nerve Fibres in Lumbricus Terrestris L

1967 ◽  
Vol 47 (3) ◽  
pp. 471-480
Author(s):  
KARI Y. H. LAGERSPETZ ◽  
ANTTI TALO
Keyword(s):  
Action Potential ◽  
Temperature Dependence ◽  
Conduction Velocity ◽  
Nerve Cord ◽  
Lumbricus Terrestris ◽  
Temperature Acclimation ◽  
Nerve Fibres ◽  
The Difference ◽  
Giant Fibres ◽  
Q10 Values

1. Temperature dependence of the conduction velocity and the duration of the rising and falling phase of action potential was studied in the median and lateral giant fibres of the nerve cord of earthworms acclimated to 13° or 23° C. 2. Compensatory acclimation of the conduction velocity was found at all temperatures studied from 6° to 32° C. However, the effect was statistically significant only at 6° C. 3. The temperature coefficient (Q10) of the conduction velocity was lower at all temperatures for the cold-acclimated animals. The difference was significant only for the temperature interval from 6° to 13° C. 4. The compensatory acclimation of the duration of the rising and falling phases of the spike was statistically significant at 6° and 13° C. The corresponding Q10 values were lower for the cold-acclimated animals. 5. The duration of the falling phase of the action potential showed the most efficient compensatory acclimation of the parameters studied.

Temperature Acclimation of the Functional Parameters of the Giant Nerve Fibres in Lumbricus Terrestris L

1967 ◽  
Vol 47 (3) ◽  
pp. 481-484
Author(s):  
ANTTI TALO ◽  
KARI Y. H. LAGERSPERTZ
Keyword(s):  
Refractory Period ◽  
Lumbricus Terrestris ◽  
Temperature Acclimation ◽  
Maximum Response ◽  
Nerve Fibres ◽  
Response Frequency ◽  
Giant Fibre ◽  
Absolute Refractory Period ◽  
The Absolute ◽  
Giant Fibres

1. The temperature dependence of the absolute refractory period and of the maximum response frequency was studied in the median and lateral giant fibres of the nerve cord of earthworms acclimated to 13° or 23° C. 2. Compensatory acclimation of the absolute refractory period in the median giant fibre was statistically significant at 6° and 13° C. The temperature coefficient Q10) was significantly lower in cold-acclimated animals. 3. Compensatory acclimation of the maximum response frequency was significant at 6° C. The ratio between the minimum impulse interval and the absolute refractory period was about 2.2. It was unaltered by temperature acclimation.

scholarly journals XI. The giant nerve cells and fibres of Halla parthenopeia

1909 ◽  
Vol 200 (262-273) ◽  
pp. 427-521 ◽  
Keyword(s):  
Nerve Cord ◽  
Transverse Section ◽  
Giant Cells ◽  
Nerve Cells ◽  
The Other ◽  
Striking Difference ◽  
Nerve Fibres ◽  
Giant Fibre ◽  
Giant Fibres ◽  
And Function

The giant nerve fibres, which form so prominent a feature in the transverse section of the nerve cord of many Annelids, were first observed in these animals by Clapaède in 1861, who, however, regarded them as canals. They were first recognised as nervous elements—“riesige dunkelrandige Nervenfasern”—by Leydig in 1864. Since then their nervous nature has been almost alternately affirmed and denied, and many widely divergent views have been advanced regarding their morphology and function. The connection of giant fibres with certain giant nerve cells was first shown in the case of Halla parthenopeia , by Spengel, in 1881. Although many other workers have investigated these elements, information is still lacking regarding several fundamental points of their structure. For instance, nothing is known regarding the neurofibrillæ of the giant cells, and although these conducting elements have been seen by five observers in the giant fibres of earthworms, there is a striking difference in their accounts: two of them refer to the presence of several neurofibrillæ, while the others describe or figure only a single fibril in each giant fibre. Further, no information is available regarding the place and mode of origin of these neurofibrillæ or their relations to other nerve elements. This defect is, no doubt, due largely to the difficulties attending the investigation of these remarkable cells and fibres; indeed, the failure of the methods usually adopted for staining nerve cells and fibres in other animals, to disclose nervous elements in the giant cells and fibres, has been held, for instance, by yon Lenhossék and Retzius, to disprove their nervous nature. The present investigation was commenced in 1900 with the view of determining the character and arrangement of the neurofibrillæ of the giant cells and fibres and the relations of these elements to the other elements of the nerve cord.

The Giant Fibre Reflex of the Earthworm, Lumbricus Terrestris L

1962 ◽  
Vol 39 (2) ◽  
pp. 219-227
Author(s):  
M. B. V. ROBERTS
Keyword(s):  
Nerve Cord ◽  
Lumbricus Terrestris ◽  
The Body ◽  
Muscle Preparation ◽  
Direct Stimulation ◽  
Giant Fibre ◽  
Low Threshold ◽  
Giant Fibres ◽  
Nerve Muscle ◽  
Stimulation Of

1. A nerve-muscle preparation including the longitudinal musculature and the giant fibres in the nerve cord of the earthworm is described. 2. Direct stimulation of the nerve cord with single shocks of increasing intensity results in two types of response: (a) a low threshold, very small twitch, resulting from a single impulse in the median giant fibre, and (b) a higher threshold, slightly larger twitch, resulting from single impulses in the median and lateral giant fibres. Both responses are highly susceptible to fatigue. 3. Stimulation of the body surface evokes a much more powerful contraction which is associated with a burst of impulses in the giant fibre. The strength of the contraction depends upon the number of impulses in the burst and this in turn upon the intensity and duration of the stimulus.

scholarly journals The Rates Of Conduction Of Nerve Fibres Of Various Diameters In Cephalopods

1938 ◽  
Vol 15 (4) ◽  
pp. 453-466 ◽  
Author(s):  
R. J. PUMPHREY ◽  
J. Z. YOUNG
Keyword(s):  
Conduction Velocity ◽  
Strong Support ◽  
Nerve Impulse ◽  
Nerve Fibres ◽  
Exact Relation ◽  
Significant Saving ◽  
Mode Of Life ◽  
The Central Nervous System ◽  
Giant Fibres ◽  
The Times

1. The rates of conduction of nerve fibres of Sepia and Loligo varying from 30 to 718µ in diameter have been estimated from records of their action potentials. The limits of conduction velocity were found to be 2.2-22.8 m./sec. at 20° C. 2. Although the fibres examined have different functions, and come from animals which differ considerably in structure and mode of life, yet the conduction rates of all of them can be approximately expressed as a single function of the diameter. These fibres, therefore, do not differ greatly from each other in any respect but size. 3. Calculation of the regression coefficient of the log. of the conduction rate on the log. of the diameter of the fibres shows that the rate increases with the power 0.614±0.027 of the diameter. On account of various sources of error however the exact relation does not necessarily lie within these limits, but it is not likely to be very far from the square root. 4. The possession of giant fibres produces a significant saving of time for the animal, it being calculated that the reaction time of a squid is about half that of a similar animal without giant fibres. 5. The presence of rapidly conducting fibres is probably also an advantage in that it decreases the discrepancies between the times of contraction of parts of the mantle at varying distances from the central nervous system. In Loligo there is a graded series of fibres with the larger in the longer nerves, and this is apparently a further device for ensuring more nearly simultaneous contraction. 6. The relative thickness of the myelin-like sheath increases from about 1% of the diameter of the axon in cephalopods to 5% in Crustacea and annelids and 25% in vertebrates: the conduction velocity of fibres of a given size also increases in the same series. This parallelism provides strong support for the view that the layer of oriented lipoids increases the velocity of propagation of the nerve impulse in proportion to its thickness.

scholarly journals Reflex conduction in the giant fibres of the earthworm

1946 ◽  
Vol 133 (870) ◽  
pp. 109-120 ◽  
Keyword(s):  
Nerve Cord ◽  
Sensory Nerves ◽  
The Other ◽  
Reverse Direction ◽  
Middle Region ◽  
Giant Fibre ◽  
Shortening Reaction ◽  
End To End ◽  
The Difference ◽  
Giant Fibres

The present work confirms the conclusion of Friedländer and others that the giant fibres mediate the end-to-end shortening reaction in the earthworm. The chief concern has been to investigate Stough’s claim that the median giant fibre conducts impulses only in the direction from head to tail and the lateral giants only in the reverse direction. Two methods have been employed. ( a ) The nerve cord was exposed at each end of the worm, and electrical records taken simultaneously from the two extremities when the surface of the worm was touched at different places. The results were usually a train of impulses in one or other giant fibre, and it was found that whenever an impulse appeared at one end of a given fibre, it always appeared at the other end of the same fibre. Each fibre, therefore, when it conducted at all, always conducted in both directions. Sensory nerves from the head appeared only connected to the median giant, since stimulation anterior to the clitellum never resulted in lateral fibre activity. Similarly, the tail appeared only to join with the lateral giant fibres. ( b ) Stough’s own method was used, and his observations confirmed, extended and re-interpreted. Either the median or both lateral fibres were divided in one segment. The success of this operation could be judged by leading off the giant fibre responses from the undissected worm (figure 5). Next day, when the worm had recovered, the shortening reflex was observed when the worm was touched at the head, the tail, or in the middle. The shortening was either throughout, or was arrested at the operation site, depending upon whether the active giant fibre was the intact or the damaged one. The results are summarized on p. 119. From both the head and the tail Stough’s observations are confirmed, and it is agreed that impulses from the head are conducted back by the median giant alone. The absence of impulses in the laterals might be due to contrary one-way conduction as Stough assumes, or to the absence of their sensory connexion with the head. But ( a ) above shows that the latter is correct, and the same must be concluded from touching the middle region of the worm, which apparently Stough did not do, for this part connects with the lateral giants, and thus affords a demonstration that these fibres may also conduct antero-posteriorly. The difference in function of the separate giant fibres, therefore, is probably related to their difference in sensory distribution.

Fenestration nodes and the wide submyelinic space form the basis for the unusually fast impulse conduction of shrimp myelinated axons

1999 ◽  
Vol 202 (15) ◽  
pp. 1979-1989 ◽  
Author(s):  
K. Xu ◽  
S. Terakawa
Keyword(s):  
Myelin Sheath ◽  
Lumbricus Terrestris ◽  
Nerve Fibres ◽  
Myelinated Nerve ◽  
Giant Fibre ◽  
Nodal Structure ◽  
Impulse Conduction ◽  
Saltatory Conduction ◽  
Giant Fibres ◽  
Myelinated Fibres

Saltatory impulse conduction in invertebrates is rare and has only been found in a few giant nerve fibres, such as the pairs of medial giant fibres with a compact multilayered myelin sheath found in shrimps (Penaeus chinensis and Penaeus japonicus) and the median giant fibre with a loose multilayered myelin sheath found in the earthworm Lumbricus terrestris. Small regions of these nerve fibres are not covered by a myelin sheath and serve as functional nodes for saltatory conduction. Remarkably, shrimp giant nerve fibres have conduction speeds of more than 200 m s-1, making them among the fastest-conducting fibres recorded, even when compared with vertebrate myelinated fibres. A common nodal structure for saltatory conduction has recently been found in the myelinated nerve fibres of the nervous systems of at least six species of Penaeus shrimp, including P. chinensis and P. japonicus. This novel node consists of fenestrated openings that are regularly spaced in the myelin sheath and are designated as fenestration nodes. The myelinated nerve fibres of the Penaeus shrimp also speed impulse conduction by broadening the gap between the axon and the myelin sheath rather than by enlarging the axon diameter as in other invertebrates. In this review, we document and discuss some of the structural and functional characteristics of the myelinated nerve fibres of Penaeus shrimp: (1) the fenestration node, which enables saltatory conduction, (2) a new type of compact multilayered myelin sheath, (3) the unique microtubular sheath that tightly surrounds the axon, (4) the extraordinarily wide space present between the microtubular sheath and the myelin sheath and (5) the main factors contributing to the fastest impulse conduction velocity so far recorded in the Animal Kingdom.

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.

The Rapid Escape Response of the Earthworm Lumbricus Terrestris L.: Overlapping Sensory Fields of the Median And Lateral Giant Fibres

1979 ◽  
Vol 83 (1) ◽  
pp. 231-238
Author(s):  
M. J. MOORE
Keyword(s):  
Conduction Velocity ◽  
Escape Response ◽  
Tactile Stimulation ◽  
Sensory Input ◽  
Lumbricus Terrestris ◽  
Sensory Neurones ◽  
Sensory Pathway ◽  
Giant Fibres ◽  
Number Of Segments ◽  
Earthworm Lumbricus

1. In undissected, freely mobile earthworms the sensory input for tactile stimulation to the MGF and LGF shows a region of overlap occupying a number of segments behind the clitellum. The average number of overlapping segments from a sample of 14 worms was 13 (range 0–28). 2. The overlap zone consists of segments from which both LGF and MGF spikes can be elicited. 3. Increasing stimulus intensity in the LGF field reduces the latency of the first spike until it reaches a minimum of 6 ms. This value is used to calculate conduction velocity of afferent impulses along the sensory pathway. 4. It is suggested, on the basis of conduction velocity, that the large sensory neurones in the segmental nerves are those mediating afferent events in the rapid escape response.

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