scholarly journals Parallel Inhibition of the Motor Giant, Segmental Giant and Fast Flexor Neurones of the Hermit Crab

1988 ◽  
Vol 140 (1) ◽  
pp. 209-226
Author(s):  
K. FRASER ◽  
W. J. HEITLER
Keyword(s):  
Electrical Stimulation ◽  
Hermit Crab ◽  
Motor Neurones ◽  
Giant Fibres ◽  
Electrical Connections ◽  
Stimulation Of

Previous work has shown that the giant fibres (GFs) of the hermit crab make excitatory electrical connections with the motor giant (MoG) and segmental giant (SG) neurones, and that the SGs in turn make connections to fast flexor (FF) motor neurones. In this paper we show that synchronous or almost-synchronous IPSPs can be elicited in all three classes of neurone by electrical stimulation of the connectives or roots. These IPSPs are depolarizing in the MoG and SG, and hyperpolarizing in the FFs. The IPSPs can functionally disconnect the MoG, SG and FF neurones from the GF command. Several interneurones have been found which initiate the IPSPs when driven with injected current. These are referred to collectively as inhibitory driver neurones (IDNs). In some cases IPSPs follow IDN spikes 1:1; in others more than one IDN spike is required to produce a single IPSP.

The Different Connections and Motor Outputs of Lateral and Medial Giant Fibres in the Crayfish

1971 ◽  
Vol 54 (2) ◽  
pp. 391-404
Author(s):  
JAMES L. LARIMER ◽  
ALAN C. EGGLESTON ◽  
LEONA M. MASUKAWA ◽  
DONALD KENNEDY
Keyword(s):  
High Speed ◽  
Motor Neurone ◽  
Giant Axons ◽  
Procion Yellow ◽  
High Speed Cinematography ◽  
Motor Neurones ◽  
Motor Outputs ◽  
Giant Fibres ◽  
Tonic System ◽  
Stimulation Of

1. High-speed cinematography was used to analyse the abdominal movements of crayfish in response to separate stimulation of medial and lateral giant axons. These films showed that the medial giant fibres command complete abdominal flexions with little flaring of the tail appendages. The lateral giants, in contrast, evoked a relatively weak flexion of the middle abdominal segments, accompanied by promotion of the exopodites of the uropods. 2. An examination of the muscles activated by the two types of giant fibres shows that differences in the connexions between the giant fibres and specific motor neurones can account for the behavioural differences observed. 3. The output of the giant fibres was determined in the sixth abdominal ganglion, where their differential effects are most pronounced. The medial giants activate motor neurones whose axons emerge from root 6 of the sixth ganglion. The lateral giants activate motor neurones whose axons emerge via roots 2 and 3, as well as those emerging via root 6. 4. The larger motor neurones associated with the giant axons in the sixth root of the sixth ganglion have been mapped by Procion Yellow injection, and the terminations of the central giant axons in the sixth ganglion have also been determined. The connexions revealed by this technique are consistent with the physiological findings. 5. The evidence suggests that root 6 of the sixth ganglion is homologous with root 3 of the more anterior ganglia. However, the giant motor neurone of the sixth ganglion has not been identified. 6. The medial and lateral giant fibres, and perhaps other specific ‘command’ interneurones, can thus drive specific ensembles of phasic motor neurones to provide a range of stereotyped quick movements. In this respect the organization of the phasic system of interneurones and motor neurones resembles that in the tonic system.

Dual actions of isthmic input to tectal neurons in a reptile, Gekko gekko

1999 ◽  
Vol 16 (5) ◽  
pp. 889-893 ◽  
Author(s):  
STEPHEN A. GEORGE ◽  
GANG-YI WU ◽  
WEN-CHANG LI ◽  
SHU-RONG WANG
Keyword(s):  
Electrical Stimulation ◽  
Optic Nerve ◽  
Optic Tectum ◽  
Nucleus Isthmi ◽  
Postsynaptic Potentials ◽  
Tectal Neurons ◽  
Electrical Connections ◽  
Stimulation Of

We analyzed postsynaptic potentials and dye-labeled morphology of tectal neurons responding to electrical stimulation of the optic nerve and of the nucleus isthmi in a reptile, Gekko gekko, in order to compare with previously reported interactions between the optic tectum and the nucleus isthmi in amphibians and birds. The results indicate that isthmic stimulation exerts inhibitory and excitatory actions on tectal cells, similar to dual isthmotectal actions in amphibians. It appears that dual actions of the isthmotectal pathway in amphibians and reptiles are shared by two subdivisions of the nucleus isthmi in birds. The morphology of tectal cells responding to isthmic stimulation is generally similar to that of tectoisthmic projecting neurons, but they differ particularly in that some tectoisthmic cells bear numerous varicosities whereas cells receiving isthmic afferents do not. Thus, it is likely that at least some tectoisthmic cells may not be in the population of tectal cells that can be affected by isthmic stimulation. Forty-four percent of injections resulted in dye-coupled labeling, suggesting extensive electrical connections between tectal cells in reptiles.

scholarly journals Wing Hair Plates in Crickets: Physiological Characteristics and Connections with Stridulatory Motor Neurones

1983 ◽  
Vol 107 (1) ◽  
pp. 21-47 ◽  
Author(s):  
C.J.H. ELLIOTT
Keyword(s):  
Electrical Stimulation ◽  
Action Potentials ◽  
Viscous Drag ◽  
Behavioural Study ◽  
Wing Hair ◽  
Motor Neurones ◽  
Association Area ◽  
The Mean ◽  
Wing Folding ◽  
Stimulation Of

(1) Hairs in the subcostal hair plates of the wings of crickets have a high angular stiffness (5.5μNm rad1) when bent about their base. The mean threshold required to elicit action potentials is 15°. Viscous drag from air movements will not deflect the hairs sufficiently to excite them; this will only occur when the hair is bent by the opposite wing. (2) The hair sensillae project to the ventral association area of the mesothoracic ganglion, but the endings of the stridulatory motor neurones are all in dorsal or lateral neuropiles of the thoracic ganglia. (3) Electrical stimulation of the hair plates evokes reliable EPSPs in opener (M99), closer (M90) and wing folding (M85) motor neurones, after latencies of 4–20 ms, depending on the neurone. Properties of the hairs and motor neurones suggest that these EPSPs in the wing folding muscle (M85) and closer (M90) could play an important role in the control of wing position seen in recent behavioural study.

The Nervous Control of Limb Autotomy in the Hermit Crab Pagurus Bernhardus (L.) and the Role of the Cuticular Stress Detector, CSD1

1977 ◽  
Vol 70 (1) ◽  
pp. 93-104 ◽  
Author(s):  
IAN FINDLAY ◽  
ALISTAIR MCVEAN
Keyword(s):  
Hermit Crab ◽  
Sensory Information ◽  
Sense Organ ◽  
Nervous Control ◽  
Limb Segment ◽  
Motor Neurones ◽  
Pagurus Bernhardus ◽  
Stimulation Of

Limb autotomy results from the fracture of a preformed breakage plane within the second limb segment. Fracture is produced by the contraction of the large anterior levator (AL) muscle at the same time as its synergist, the posterior levator (PL) muscle. The AL force is thus directed on to a small portion of the breakage plane; withdrawal of this plug initiates cuticular fracture. Autotomy is a response to damage inflicted on the limb. In the absence of sensory information from the second limb segment there is less activity in the units serving the PL. It is shown that stimulation of the sense organ, cuticular stress detector one, provides feedback to PL motor neurones. The feedback is an integral part of the nervous control of limb autotomy.

Thoracic connections between crayfish giant fibres and motor giant neurones reverse abdominal pattern

1993 ◽  
Vol 181 (1) ◽  
pp. 329-333
Author(s):  
WJ Heitler ◽  
K Fraser
Keyword(s):  
Motor Output ◽  
Giant Fibre ◽  
Motor Neurones ◽  
Giant Fibres ◽  
Tail Flip ◽  
Electrical Connections

The escape tail-flip of the crayfish is ‘commanded’ by two bilaterally paired sets of giant fibre (GF) interneurones, the lateral giant (LG) and medial giant (MG) (see e.g. Wine, 1984, for a review). The two classes of GF respond to different stimuli and initiate tail-flips with different kinematic forms. An arousal stimulus applied to the front of the animal initiates a spike in the MG system, and this causes a tail-flip that drives the animal directly backwards, away from the stimulus. An arousal stimulus applied to the rear of the animal initiates a spike in the LG system, and this causes a tail-flip that drives the animal upwards and forwards, again moving it away from the stimulus. The major motor output path from the GFs is through monosynaptic rectifying electrical connections to a class of powerful trunk flexor motor neurones called the motor giant (MoG) neurones (Furshpan and Potter, 1959a). There is one MoG neurone in each hemisegment of the thorax and abdomen.

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.

Electrical Stimulation of the Raphe Nuclei: Effects on Runway Performance

1969 ◽  
Author(s):  
H. B. Van Twyver ◽  
M. D. Fairchild ◽  
M. B. Sterman
Keyword(s):  
Electrical Stimulation ◽  
Raphe Nuclei ◽  
Runway Performance ◽  
Raphé Nuclei ◽  
Stimulation Of
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