scholarly journals THE REACTION OF NEREIS VIRENS TO UNILATERAL TENSION OF ITS MUSCULATURE

1923 ◽  
Vol 5 (4) ◽  
pp. 451-452 ◽  
Author(s):  
A. R. Moore
Keyword(s):  
Nerve Cord ◽  
Ventral Nerve Cord ◽  
Nereis Virens ◽  
Anterior Segments ◽  
The Brain

1. The anterior segments of Nereis are oriented reflexly by passive unilateral tension of the posterior musculature. 2. The afferent impulses of the homostrophic reflex rise from any part of the worm and are conducted forward by way of the ventral nerve cord. 3. The efferent impulses flow out from the brain and anterior two or three ventral ganglia. 4. The homostrophic reflex may be partially or wholly masked by stereotropism.

scholarly journals MUSCLE TENSION AND REFLEXES IN THE EARTHWORM

1923 ◽  
Vol 5 (3) ◽  
pp. 327-333 ◽  
Author(s):  
A. R. Moore
Keyword(s):  
Nerve Cord ◽  
Ventral Nerve Cord ◽  
Body Wall ◽  
Muscle Tension ◽  
Posterior Part ◽  
The Body ◽  
Entire Length ◽  
Sensory Cells ◽  
Ventral Region ◽  
Anterior Segments

1. By the use of preparations of earthworm in which the cutaneous receptors have been anesthetized with a solution of M/8 MgCl2, it is shown that peristalsis can be initiated by tension alone. 2. The receptors of the tension reflex are the intermyal sensory cells of the ventral region of the body wall. 3. It is concluded that Straub obtained the tension reflex because his preparations contained the intermyal receptors; Budington was unable to observe the tension reflex in any preparation from which the intermyal receptors had been removed. 4. Intermyal receptors are the receptors of the following reaction: Passive unilateral tension of the posterior part of an earthworm induces active homolateral tension of the musculature of the anterior segments, and results in the course of progress being brought into line with the enforced orientation of the tail. This reaction is termed the homostrophic reflex. 5. The receptors for the reaction are distributed throughout the entire length of the worm, the effectors are limited to the anterior 15 to 20 segments. The impulse is conducted by the ventral nerve cord. 6. The interaction of the homostrophic reflex and tropisms is considered.

scholarly journals Identification and Expression Analysis of Tryptophan Hydroxylase in the Brain and Ventral Nerve Cord of RagwormNeanthes japonica(Polychaeta, Annelida)

2016 ◽  
Vol 300 (2) ◽  
pp. 415-424
Author(s):  
Shun Wang ◽  
Zhe Dong ◽  
Shen Li ◽  
Haotian Yin ◽  
Zhifu Zhao ◽  
...  
Keyword(s):  
Expression Analysis ◽  
Nerve Cord ◽  
Ventral Nerve Cord ◽  
Tryptophan Hydroxylase ◽  
The Brain

First detection of serotonin in the nervous system of the marine calanoid copepod Centropages typicus

2005 ◽  
Vol 85 (1) ◽  
pp. 71-72 ◽  
Author(s):  
D. Benzid ◽  
C. Morris ◽  
R.-M. Barthélémy
Keyword(s):  
Nervous System ◽  
Nerve Cord ◽  
Ventral Nerve Cord ◽  
Calanoid Copepod ◽  
Marine Species ◽  
Biological Processes ◽  
Calanoid Copepods ◽  
The Brain ◽  
Serotoninergic Nervous System ◽  
Centropages Typicus

This investigation constitutes the first study of the serotoninergic nervous system in calanoid copepods (crustaceans). Serotonin (5-HT), a neurotransmitter which plays a part in many biological processes, has been detected by immunofluorescence in the brain, the circumoesophageal collar and the ventral nerve cord of the marine species Centropages typicus.

scholarly journals Whole-central nervous system functional imaging in larval Drosophila

2015 ◽  
Vol 6 (1) ◽  
Author(s):  
William C. Lemon ◽  
Stefan R. Pulver ◽  
Burkhard Höckendorf ◽  
Katie McDole ◽  
Kristin Branson ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Nerve Cord ◽  
Ventral Nerve Cord ◽  
Activity Patterns ◽  
Network Activity ◽  
Imaging Data ◽  
Spatiotemporal Resolution ◽  
Functional Connections ◽  
The Brain

Abstract Understanding how the brain works in tight concert with the rest of the central nervous system (CNS) hinges upon knowledge of coordinated activity patterns across the whole CNS. We present a method for measuring activity in an entire, non-transparent CNS with high spatiotemporal resolution. We combine a light-sheet microscope capable of simultaneous multi-view imaging at volumetric speeds 25-fold faster than the state-of-the-art, a whole-CNS imaging assay for the isolated Drosophila larval CNS and a computational framework for analysing multi-view, whole-CNS calcium imaging data. We image both brain and ventral nerve cord, covering the entire CNS at 2 or 5 Hz with two- or one-photon excitation, respectively. By mapping network activity during fictive behaviours and quantitatively comparing high-resolution whole-CNS activity maps across individuals, we predict functional connections between CNS regions and reveal neurons in the brain that identify type and temporal state of motor programs executed in the ventral nerve cord.

scholarly journals A single-cell transcriptomic atlas of the adult Drosophila ventral nerve cord

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Aaron M Allen ◽  
Megan C Neville ◽  
Sebastian Birtles ◽  
Vincent Croset ◽  
Christoph Daniel Treiber ◽  
...  
Keyword(s):  
Single Cell ◽  
Nerve Cord ◽  
Ventral Nerve Cord ◽  
Sensory Information ◽  
Neuronal Cell ◽  
Cell Types ◽  
Distinct Cell ◽  
Old Adult ◽  
And Behavior ◽  
The Brain

The Drosophila ventral nerve cord (VNC) receives and processes descending signals from the brain to produce a variety of coordinated locomotor outputs. It also integrates sensory information from the periphery and sends ascending signals to the brain. We used single-cell transcriptomics to generate an unbiased classification of cellular diversity in the VNC of five-day old adult flies. We produced an atlas of 26,000 high-quality cells, representing more than 100 transcriptionally distinct cell types. The predominant gene signatures defining neuronal cell types reflect shared developmental histories based on the neuroblast from which cells were derived, as well as their birth order. The relative position of cells along the anterior-posterior axis could also be assigned using adult Hox gene expression. This single-cell transcriptional atlas of the adult fly VNC will be a valuable resource for future studies of neurodevelopment and behavior.

scholarly journals Habituation of swimming activity in the medicinal leech

1985 ◽  
Vol 116 (1) ◽  
pp. 169-188
Author(s):  
E. A. Debski ◽  
W. O. Friesen
Keyword(s):  
Nerve Cord ◽  
Ventral Nerve Cord ◽  
Body Wall ◽  
Spontaneous Recovery ◽  
Medicinal Leech ◽  
The Body ◽  
Swimming Activity ◽  
Stimulus Generalization ◽  
Anterior Segments ◽  
Stimulation Of

Tactile stimulation (light stroking) of a body wall flap attached to the ventral nerve cord of the medicinal leech evokes episodes of swimming activity. This swimming response undergoes habituation, involving changes in swim initiation and swim maintenance. Repeated stimulation of the body wall flap evoked swimming activity between three and 39 times before this response failed. During repetitive stimulation, the length of swim episodes decreased by about 50%. The number of swim episodes which could be elicited was not correlated with swim episode length. Following habituation, swim initiation showed significant spontaneous recovery, but swim episode length returned only to 60% of control values. In preparations where spontaneous recovery was followed by rehabituation, the number of swim episodes elicited declined with each habituation-recovery sequence. Additional stimulation immediately following habituation trials had a dual effect: recovery of the swimming response was delayed, but the lengths of swim episodes following spontaneous recovery were increased. Pinching the body wall flap immediately restored the swimming response in an habituated preparation. Swim initiation habituated more rapidly during stimulation of anterior body wall flaps than during stimulation of mid-body or posterior flaps. However, swim length was independent of this regional variation in swim responsiveness. The number of swim episodes elicited by stimulation of body wall flaps attached to posterior or anterior segments depended upon whether this segment was stimulated before or after other flaps. In contrast, in mid-body segments there was no evidence for such stimulus generalization. The lengths of swim episodes elicited during sequential stimulation of several body wall flaps were independent of the stimulation sequence. We propose that separate processes control swim initiation and swim maintenance. These processes must be repeated in most, if not all, of the segmental ganglia of the leech ventral nerve cord.

Projection of FMRFamide-like neuropeptide-producing neurosecretory cells from silkworm brain into ventral nerve cord and retrocerebral complex

2012 ◽  
Vol 144 (3) ◽  
pp. 458-466 ◽  
Author(s):  
Bo Yong Kim ◽  
Hwa Young Song ◽  
Mi Young Kim ◽  
Pil Don Kang ◽  
Min Ho Cha ◽  
...  
Keyword(s):  
Juvenile Hormone ◽  
Bombyx Mori ◽  
Nerve Cord ◽  
Ventral Nerve Cord ◽  
Neurosecretory Cells ◽  
Single Pair ◽  
Corpus Cardiacum ◽  
Pars Intercerebralis ◽  
Median Region ◽  
The Brain

AbstractUsing immunostaining methodology, we traced the axonal projection of FMRFamide (Phe-Met-Arg-Phe-NH2)-like immunoreactive (LI) medial neurosecretory cells (MNCs) and lateral neurosecretory cells (LNCs) from the brain into the ventral nerve cord (VNC) and retrocerebral complex in Bombyx mori (L.) (Lepidoptera: Bombycidae). Of the seven pairs of FMRFamide-LI MNCs, one pair extended its axons from the brain pars intercerebralis into the VNC ipsilateral connective where they appeared to terminate. The axons of the remaining MNCs ran through decussation in the brain median region and contralateral nervi corporis cardiaci (NCC) I out of the brain, and eventually innervated the contralateral corpus cardiacum (CC). Axons from the single pair of FMRFamide-LI LNCs projected into the ipsilateral NCC II fused with NCC I without decussation in the brain, and finally terminated in the CC. These results suggest that transport of the FMRFamide-like neuropeptide from may be related to the modulation of functions such as gut contraction in MNCs terminating in the VNC, and regulation of production and/or secretion of specific hormones such as juvenile hormone in MNCs and LNCs terminating in the CC.

Influence of the Supra-oesophageal Ganglion on Posterior Regeneration in Nereis diversicolor

Development ◽  
1960 ◽  
Vol 8 (2) ◽  
pp. 112-118
Author(s):  
R. B. Clark ◽  
D. G. Bonney
Keyword(s):  
B Cells ◽  
Nerve Cord ◽  
Ventral Nerve Cord ◽  
Secretory Activity ◽  
Neurosecretory Cells ◽  
Normal Rate ◽  
Nereis Diversicolor ◽  
The Brain

Hubl (1956) demonstrated that if the supra-oesophageal ganglion of lumbricid oligochaetes is removed at the time of amputation of a number of posterior segments, caudal regeneration is totally inhibited, but if the ganglion is not removed until 24–48 hours after amputation of the posterior segments, regeneration proceeds at the normal rate. A comparable phenomenon may occur in nereid polychaetes. Removal of the prostomium (Casanova, 1955) or, more precisely, of the supra-oesophageal ganglion (Durchon, 1956), retards regeneration but does not prevent it, but as these experiments were performed. On the day following amputation of the posterior segments it is still not certain whether the brain of Nereis is, at any stage, essential for posterior regeneration as it clearly is in lumbricids. In his investigation of Lumbricus and Allolobophora, Hubl (1956) found that neurosecretory cells in the supra-oesophageal ganglion, the b-cells, showed intense secretory activity as soon as the worm was injured and the ventral nerve-cord damaged.

Sign in / Sign up

Export Citation Format

Share Document