A giant fibre bypass for the fly

2014 ◽  
Vol 217 (17) ◽  
pp. 2988-2989
Author(s):  
M. Zwart
Keyword(s):  
Giant Fibre

THE HISTOLOGY OF THE GIANT FIBRE SYSTEM IN THE ABDOMINAL VENTRAL NERVE CORD OF THE DESERT LOCUST

1970 ◽  
Vol 102 (9) ◽  
pp. 1163-1168 ◽  
Author(s):  
W. D. Seabrook
Keyword(s):  
Single Cell ◽  
Nerve Cord ◽  
Ventral Nerve Cord ◽  
Schistocerca Gregaria ◽  
Desert Locust ◽  
Giant Fibre ◽  
Metathoracic Ganglion ◽  
Giant Fibres ◽  
Giant Fibre System

AbstractSchistocerca gregaria possess four neurones of giant fibre proportions within the abdominal ventral nerve cord. These fibres arise from single cell bodies in the terminal ganglionic mass and pass without interruption to the metathoracic ganglion. Fibres become reduced in diameter when passing through a ganglion. Branching of the giant fibres occurs in abdominal ganglia 6 and 7.

Neurofilament phosphorylation and axon diameter in the squid giant fibre system

Neuroscience ◽  
1999 ◽  
Vol 88 (1) ◽  
pp. 327-336 ◽  
Author(s):  
R Martin ◽  
R Door ◽  
A Ziegler ◽  
W Warchol ◽  
J Hahn ◽  
...  
Keyword(s):  
Axon Diameter ◽  
Giant Fibre ◽  
Neurofilament Phosphorylation ◽  
Giant Fibre System

Structure and Function of the Lateral Giant Neurone of the Primitive Crustacean Anaspides Tasmaniae

1979 ◽  
Vol 78 (1) ◽  
pp. 121-136
Author(s):  
GERALD E. SILVEY ◽  
IAN S. WILSON
Keyword(s):  
Action Potentials ◽  
Tactile Stimulation ◽  
Large Diameter ◽  
Whole Body ◽  
Giant Fibre ◽  
Single Action ◽  
Giant Neurone ◽  
And Function ◽  
Thoracic And Abdominal ◽  
Stimulation Of

The syncarid crustacean Anaspides tasmaniae rapidly flexes its free thoracic and abdominal segments in response to tactile stimulation of its body. This response decrements but recovers in slightly more than one hour. The fast flexion is evoked by single action potentials in the lateral of two large diameter fibres (40 μm) which lie on either side of the cord. The lateral giant fibre is made up of fused axons of 11 neurones, one in each of the last 5 thoracic and 6 abdominal ganglia. The soma of each neurone lies contralateral to the axon. Its neurite crosses that of its counterpart in the commissure and gives out dendrites into the neuropile of each hemiganglion. The lateral giant neurone receives input from the whole body but fires in response only to input from the fourth thoracic segment posteriorly. Both fibres respond with tactile stimulation of only one side. Since neither current nor action potentials spread from one fibre to the other, afferents must synapse with both giant neurones. The close morphological and physiological similarities of the lateral giant neurone in Anaspides to that in the crayfish (Eucarida) suggest that the lateral giant system arose in the ancestor common to syncarids and eucarids, prior to the Carboniferous.

Propagation of electrical signals along giant nerve fibres

1952 ◽  
Vol 140 (899) ◽  
pp. 177-183 ◽  
Keyword(s):  
Sea Water ◽  
Giant Axon ◽  
High Concentration ◽  
Nerve Fibres ◽  
Giant Fibre ◽  
Electrical Signals ◽  
Small Fibre ◽  
The Central Nervous System ◽  
Good Conductor ◽  
Ionic Movement

In this part of the discussion we shall attempt to describe the way in which electrical signals are propagated along the giant nerve fibres of squids and cuttlefish. These fibres consist of cylinders of protoplasm, 0.2 to 0.6 mm in diameter, and ire bounded by a thin membrane which acts as a barrier to ionic movement. The protoplasm, or axoplasm as it is commonly called, is an aqueous gel which is a reasonably good conductor of electricity. It contains a high concentration of K + and a low concentration of Na + and Cl - , this situation being the reverse of that in the animal’s blood or sea water. Axons which are left in sea water slowly lose potassium and gain sodium. This process takes about 24 hours and is roughly 80 000 times slower than the diffusion of ions out of a cylinder of gelatin of the same size. The interchange of sodium and potassium is very greatly accelerated by stimulating the fibres. Experiments with tracers, such as those made by Keynes & Lewis (1951) or Rothenberg (1950), allow the interchange to be measured quantitatively, and there is general agreement that the impulse is associated with an entry of 3 to 4 µ µ mol of Na + through 1 cm 2 of membrane and an exit of a corresponding quantity of K + . These quantities are very small compared with the total number of ions inside the fibre. In the giant axon of the squid the quantity of potassium lost in each impulse corresponds to only about 1 millionth if the total internal potassium. One would therefore expect that a giant fibre should be able to carry a great many impulses without recharging its batteries by metabolism. On the other hand, a very small fibre such as a dendrite in the central nervous system should be much more dependent on metabolism since the ratio of surface to volume may be nearly 1000 times greater.

scholarly journals The Segmental Giant Neurone of the Hermit Crab Eupagurus Bernhardus

1986 ◽  
Vol 125 (1) ◽  
pp. 245-269 ◽  
Author(s):  
W. J. Heitler ◽  
K. Fraser
Keyword(s):  
Cell Body ◽  
Hermit Crab ◽  
Small Cell ◽  
Electrical Synapse ◽  
Giant Fibre ◽  
Anatomy And Physiology ◽  
Motor Neurones ◽  
Evolutionary Paths ◽  
Contralateral Motor ◽  
Giant Fibre System

The anatomy and physiology of the segmental giant (SG) neurone of the fourth abdominal ganglion of the hermit crab is described. The SG has an apparently blindending axon in the first root and a small cell body in the anterior ipsilateral ventral quadrant of the ganglion. There is a large ipsilateral neuropile arborization with prominent dendrites lined up along the course of the ipsilateral giant fibre (GF). The SG receives 1:1 input from the ipsilateral GF via an electrical synapse which is usually rectifying. SG activation produces a large EPSP in all ipsilateral and some contralateral fast flexor excitor (FF) motor neurones. The major input to FFs resulting from GF activation appears to be mediated via the SG. It also produces a small EPSP in ipsilateral and contralateral motor giant neurones. The properties of the hermit crab SG are compared to those of the crayfish SG, and the implications of the SG for the possible evolutionary paths of the giant fibre system are discussed.

The pharmacology of an insect ganglion: actions of carbamylcholine and acetylcholine

1976 ◽  
Vol 64 (1) ◽  
pp. 13-23
Author(s):  
D. B. Sattelle ◽  
A. S. McClay ◽  
R. J. Dowson ◽  
J. J. Callec
Keyword(s):  
Synaptic Transmission ◽  
Dose Response ◽  
Response Curve ◽  
Periplaneta Americana ◽  
Electrophysiological Recording ◽  
Cholinergic Agonists ◽  
Giant Fibre ◽  
Response Data ◽  
Gap Technique ◽  
Monosynaptic Epsp

1. Methods for presenting dose-response data for the ganglionic actions of cholinergic agonists (e.g. carbamylcholine) are compared, using the mannitol-gap technique for electrophysiological recording of synaptic events at the cercal nerve, giant fibre synapse of the sixth abdominal ganglion of the cockroach Periplaneta americana. 2. At concentrations around 10(−5)M, carbamylcholine has no effect on ganglionic polarization but potentiates the monosynaptic EPSP. At 10(−4)M and higher concentrations, ganglionic depolarization is accompanied by a reduction of EPSP. 3. Pretreatment with eserine (10(−6) M) considerably shifts the dose-response curve for acetylcholine so that synaptic transmission is consistently sensitive to 10(−6) M acetylcholine.

The Giant Nerve-Fibres in the Central Nervous System of Myxicola (Polychaeta, Sabellidae)

1948 ◽  
Vol s3-89 (5) ◽  
pp. 1-45
Author(s):  
J.A. C. NICOL
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Nerve Cord ◽  
Size Structure ◽  
Nerve Cells ◽  
The Body ◽  
Usual Sense ◽  
Fibrous Sheath ◽  
Giant Fibre ◽  
The Central Nervous System

1. A description is given of the main features of the central nervous system of Myxicola infundibulum Rénier. 2. The nerve-cord is double in the first four thoracic segments and single posteriorly. It shows segmental swellings but is not ganglionated in the usual sense in that nerve-cell accumulations are not related directly to such swellings of the cord. 3. A very large axon lies within the dorsal portion of the nerve-cord and extends from the supra-oesophageal ganglia to the posterior end of the animal. It is small in the head ganglia where it passes transversely across the mid-line, increases in diameter in the oesophageal connectives, and expands to very large size, up to 1 mm., in the posterior thorax and anterior abdomen, and gradually tapers off to about 100µ in the posterior body. It shows segmental swellings corresponding to those of the nerve-cord in each segment. It occupies about 27 per cent, of the volume of the central nervous system and 0.3 per cent, of the volume of the animal. The diameter of the fibre increases during contraction of the worm. 4. The giant fibre is a continuous structure throughout its length, without internal dividing membranes or septa. Usually a branch of the giant fibre lies in each half of the nerve-cord in the anterior thoracic segments and these several branches are continuous with one another longitudinally and transversely. 5. The giant fibre is connected with nerve-cells along its entire course; it arises from a pair of cells in the supra-oesophageal ganglia, and receives the processes of many nerve-cells in each segment. There is no difference between the nerve-cells of the giant fibre and the other nerve-cells of the cord. 6. A distinct fibrous sheath invests the giant fibre. A slight concentration of lipoid can be revealed in this sheath by the use of Sudan black. 7. About eight peripheral branches arise from the giant fibre in each segment. They have a complex course in the nerve-cord where they anastomose with one another and receive the processes of nerve-cells. Peripherally, they are distributed to the longitudinal musculature. 8. Specimens surviving 16 days following section of the nerve-cord in the thorax have shown that the giant fibre does not degenerate in front of or behind a cut, thus confirming that it is a multicellular structure connected to nerve-cells in the thorax and abdomen. 9. It is concluded that the giant fibre of M. infundibulum is a large syncytial structure, extending throughout the entire central nervous system and the body-wall of the animal. 10. The giant fibre system of M. aesthetica resembles that of M. infundibulum. 11. Some implications of the possession of such a giant axon are discussed. It is suggested that its size, structure, and simplicity lead to rapid conduction and thus effect a considerable saving of reaction time, of considerable value to the species when considered in the light of the quick contraction which it mediates. The adoption of a sedentary mode of existence has permitted this portion of the central nervous system to become developed at the expense of other elements concerned with errant habits.

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.

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