Facilitation in the Rapid Response of the Earthworm, Lumbricus Terrestris L

1966 ◽  
Vol 45 (1) ◽  
pp. 141-150
Author(s):  
M. B. V. ROBERTS
Keyword(s):  
Nerve Cord ◽  
Lumbricus Terrestris ◽  
Rapid Response ◽  
Giant Fibre ◽  
Rapid Responses ◽  
Earthworm Lumbricus ◽  
Marked Tendency

1. Successive rapid responses of the earthworm show a marked tendency to increase in size on repetition. 2. It is shown that this "staircase" phenomenon is not due to peripheral facilitation either on the afferent or efferent side of the reflex, but to summation in the nerve cord and evidence is presented that it occurs at "giant-to-motor" junctions. 3. Facilitation is most pronounced in preparations whose "giant-to-motor" junctions are accommodated. In such cases a single impulse in the median giant fibre is ineffective, two or more being required to produce a rapid response throughout the length of the animal. 4. Fatigue and facilitation in the earthworm is discussed in relation to similar phenomena in other invertebrates.

The Giant Fibre Reflex of the Earthworm, Lumbricus Terrestris L

1962 ◽  
Vol 39 (2) ◽  
pp. 229-237
Author(s):  
M. B. V. ROBERTS
Keyword(s):  
Neuromuscular Junctions ◽  
Lumbricus Terrestris ◽  
Repetitive Stimulation ◽  
Motor Neurone ◽  
Giant Fibre ◽  
Sensory Neurones ◽  
Contractile Mechanism ◽  
Motor Neurones ◽  
Earthworm Lumbricus

1. The purpose of this investigation was to locate the site of fatigue in the giant fibre reflex of the earthworm. 2. The following sites do not show rapid fatigue on repetitive stimulation: contractile mechanism of muscle, neuromuscular junctions, junctions in the course of the motor neurone tracts. 3. Rapid failure of transmission (accommodation) occurs between the sensory neurones and the giant fibre, and between the giant fibre and the motor neurones.

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.

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 extracellular hemoglobin of the earthworm, Lumbricus terrestris. Determination of subunit stoichiometry

1993 ◽  
Vol 268 (18) ◽  
pp. 13539-13547 ◽  
Author(s):  
D.W. Ownby ◽  
H. Zhu ◽  
K. Schneider ◽  
R.C. Beavis ◽  
B.T. Chait ◽  
...  
Keyword(s):  
Lumbricus Terrestris ◽  
Subunit Stoichiometry ◽  
Earthworm Lumbricus
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