Electrophysiological correlates of rapid escape reflexes in intact earthworms, <i>Eisenia foetida</i>. II. Effects of food deprivation on the functional development of giant nerve fibers

Vining, Elizabeth P.; O'Gara, Bruce A.; Drewes, Charles D.

doi:10.1002/neu.480130406

Cited by 4 publications

(2 citation statements)

References 15 publications

(27 reference statements)

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“…As a consequence of this pattern of MGF development there was a slight inflection in the age-dependent increase in MGF conduction velocity between days 10 and 30. The inflection has consistently appeared in other experimental groups of animals and is discussed in the following article (Vining, O'Gara, and Drewes, 1982). After the inflection, MGF conduction velocity continued to increase gradually from days 30 to 60, eventually stabilizing at about 8-11 m s-l in most adult worms.…”

Section: Hatching To Adultmentioning

confidence: 94%

Electrophysiological correlates of rapid escape reflexes in intact earthworms, Eisenia foetida. I. Functional development of giant nerve fibers during embryonic and postembryonic periods

1982

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Grids of recording electrodes etched onto printed circuit boards were used for noninvasive recording of medial (MGF) and lateral (LGF) giant nerve fiber spikes in developing earthworms, Eisenia foetida. Stereotyped patterns of through-conducted giant fiber spikes, evoked by light tactile stimulation, were first detectable in the normal crawling embryonic stage and continued to be detectable throughout postembryonic development. Giant fiber spiking activity in normal crawling embryos was accompanied by stereotyped muscle activity and rapid escape withdrawal, suggesting that giant fiber reflex pathways are functionally intact before the worm hatches. For both the MGF and LFG, several age-dependent changes were noted, including the following: increases in spike conduction velocity, increases in giant fiber diameter, and decreases in spike duration. The MGF conduction velocity in normal crawling embryos was 1.1-1.6 m s-1 (6-7 micrometers diameter) and increased to 7.0-8.5 m s-1 (20-25 micrograms diameter) by 60 days after hatching. The LGF conduction velocity in normal crawling embryos was 0.7-1.1 m s-1 (2.5-4.0 micrometers diameter) and increased to 4.0-5.5 m s-1 (8-14 micrometers diameter) by 60 days after hatching. During postembryonic development MGF and LGF conduction velocities were linearly related to fiber diameter.

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Section: Hatching To Adultmentioning

confidence: 94%

Electrophysiological correlates of rapid escape reflexes in intact earthworms, Eisenia foetida. I. Functional development of giant nerve fibers during embryonic and postembryonic periods

1982

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“…Fur-GRAS thermore, tail-amputated animals regained the reflex faster and to a higher degree than individuals with extirpated ganglia at the same body level and unreduced body mass. The postembryonal development of giant fibers in Eiseniu is only weakly affected by moderate food deprivation, although under such conditions body growth is considerably reduced Wining, O'Gara, and Drewes, 1982). The growth of septal muscles (from the size in NR to that typical for FR) is presumably not decisive, as up to ten days p.0.…”

Section: Discussionmentioning

confidence: 97%

The tail flattening reflex in Lumbricus: Reconstitution after tail amputation and modifications in segmental nerve roots

Gras

1984

J. Neurobiol.

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On stimulation of the head, the caudal 20-30 segments of intact earthworms exhibit a marked dorso-ventral flattening reflex which is an element of the escape response. When the tail is removed this reflex is reconstituted gradually in segments anterior to the amputation level without regeneration of new tail segments. It takes longer to reestablish the flattening if larger parts of the body are cut off, but after 60 days p.o. all animals regained the full response independent of the number of segments amputated. Extirpation of three consecutive ganglia from the ventral nerve cord also suffices to develop flattening anterior to the operated segments, but the reaction is less pronounced and appears later than after tail amputation. Moreover, it vanishes at the same time the normal tail flattening is observed again, presumably after regeneration across the gap in the cord. In different regions of the body, area and perimeter distributions of transversely sectioned axons in the three pairs of segmental nerves (SN I-III) of the cord were measured. Characteristic changes along the length of the animal were found for SN I and SN III. In tail segments the axonal size distributions are more variable than "typical" segments. The flattening reflex is mediated by axons in SN III (Pallas and Drewes, 1981). In body segments having reconstituted behavioral characteristics of the lost tail segments, the area of the largest axons and the general size distribution in SN III approximate those found in normal tail segments.

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sublethal neurotoxic effects of the fungicide benomyl on earthworms (Eisenia fetida)

1987

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Earthworms Eisenia fetida were treated by surface contact exposure for 4 days with the fungicide benomyl. Non‐invasive electrophysiological recordings after treatment with sublethal concentrations of 0.2‐25 mg benomyl litre−1 of water (=0.003−0.435 μg benomyl cm−2 of filter paper) indicated concentration‐dependent decreases in conduction velocity for the medial and lateral giant nerve fibres. Threshold concentration for these effects was approximately two orders of magnitude less than the LC50. The effects on velocity were not accompanied by alterations in refractory period or impairment of locomotory reflexes, but persisted for at least several weeks after treatment. Morphometric analysis of treated animals revealed a disruption of the myelin‐like sheath surrounding giant fibres but no change in fibre diameters. It is concluded that benomyl had subtle and sublethal neurotoxic effects on earthworm giant nerve fibres. The data indicate that giant fibre conduction velocity is a particularly sensitive parameter for detecting these effects in intact worms.

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Electrophysiological correlates of rapid escape reflexes in intact earthworms, Eisenia foetida. II. Effects of food deprivation on the functional development of giant nerve fibers

Cited by 4 publications

References 15 publications

Electrophysiological correlates of rapid escape reflexes in intact earthworms, Eisenia foetida. I. Functional development of giant nerve fibers during embryonic and postembryonic periods

Electrophysiological correlates of rapid escape reflexes in intact earthworms, Eisenia foetida. I. Functional development of giant nerve fibers during embryonic and postembryonic periods

The tail flattening reflex in Lumbricus: Reconstitution after tail amputation and modifications in segmental nerve roots

sublethal neurotoxic effects of the fungicide benomyl on earthworms (Eisenia fetida)

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