scholarly journals Properties of Ventral Cerebral Neurones Involved in the Feeding System of the Snail, Lymnaea Stagnalis

1984 ◽  
Vol 108 (1) ◽  
pp. 257-272
Author(s):  
C. R. MCCROHAN
Keyword(s):  
Lymnaea Stagnalis ◽  
Rhythmic Activity ◽  
Cell Types ◽  
Feeding System ◽  
Oral Aperture ◽  
Axonal Projections ◽  
Cerebral Ganglia ◽  
Buccal Ganglia ◽  
Relationship Of ◽  
The Relationship

Four identified neurone types (CV3, 7, 5 and 6), located in the ventral cerebral ganglia of Lymnaea stagnalis, are described. These cells have axonal projections in one or more of the nerves innervating the lips. In addition, they show rhythmic synaptic inputs leading to strong burst activity in phase with cyclic output from the buccal ganglia, suggesting a role in the control of the oral aperture during feeding. The innervation of lip muscle by one of the cell types (CV7) is confirmed electrophysiologically. The relationship of rhythmic activity in CV cells with that in the buccal feeding system is discussed.

Novel interneuron having hybrid modulatory-central pattern generator properties in the feeding system of the snail, Lymnaea stagnalis

1995 ◽  
Vol 73 (1) ◽  
pp. 112-124 ◽  
Author(s):  
M. S. Yeoman ◽  
A. Vehovszky ◽  
G. Kemenes ◽  
C. J. Elliott ◽  
P. R. Benjamin
Keyword(s):  
Central Pattern Generator ◽  
Lymnaea Stagnalis ◽  
Cell Types ◽  
Pattern Generator ◽  
Feeding System ◽  
Buccal Ganglia ◽  
Steady Current ◽  
Feeding Rhythm ◽  
Symmetrical Pair ◽  
Feeding Rhythms

1. We used intracellular recording techniques to examine the role of a novel type of protraction phase interneuron, the lateral N1 (N1L) in the feeding system of the snail Lymnaea stagnalis. 2. The N1Ls are a bilaterally symmetrical pair of electrotonically coupled interneurons located in the buccal ganglia. Each N1L sends a single axon to the contralateral buccal ganglia. Their neurite processes are confined to the buccal neuropile. 3. In the isolated CNS, depolarization of an N1L is capable of driving a full (N1-->N2-->N3), fast (1 cycle every 5 s) fictive feeding rhythm. This was unlike the previously described N1 medial (N1M) central pattern generator (CPG) interneurons that were only capable of driving a slow, irregular rhythm. Attempts to control the frequency of the fictive feeding rhythm by injecting varying amounts of steady current into the N1Ls were unsuccessful. This contrasts with a modulatory neuron, the slow oscillator (SO), that has very similar firing patterns to the N1Ls, but where the frequency of the rhythm depends on the level of injected current. 4. The N1Ls' ability to drive a fictive feeding rhythm in the isolated preparation was due to their strong, monosynaptic excitatory chemical connection with the N1M CPG interneurons. Bursts of spikes in the N1Ls generated summating excitatory postsynaptic potentials (EPSPs) in the N1Ms to drive them to firing. The SO excited the N1M cells in a similar way, but the EPSPs are strongly facilitatory, unlike the N1L-->N1M connection. 5. Fast (1 cycle every 5 s) fictive feeding rhythms driven by the N1L occurred in the absence of spike activity in the SO modulatory neuron. In contrast, the N1L was usually active in SO-driven rhythms. 6. The ability of the SO to drive the N1L was due to strong electrotonic coupling, SO-->N1L. The weaker coupling in the opposite direction, N1L-->SO, did not allow the N1L to drive the SO. 7. Experiments on semintact lip-brain preparations allowed fictive feeding to be evoked by application of 0.1 M sucrose to the lips (mimicking the normal sensory input) rather than by injection of depolarizing current. Rhythmic bursting, characteristic of fictive feeding, began in both the SO and N1L at exactly the same time, indicating that these two cell types are activated in "parallel" to drive the feeding rhythm. 8. The N1L is also part of the CPG network. It Excited the N2s and inhibited the N3 phasic (N3p) and N3 tonic (N3t) CPG interneurons like the N1Ms.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Initiation of Feeding Motor Output by an Identified Interneurone in the Snail Lymnaea Stagnalis

1984 ◽  
Vol 113 (1) ◽  
pp. 351-366
Author(s):  
C. R. MCCROHAN
Keyword(s):  
Lymnaea Stagnalis ◽  
Motor Output ◽  
Synaptic Inputs ◽  
Axonal Projections ◽  
Cerebral Ganglia ◽  
Buccal Ganglia

1. The cerebral ventral 1 (CV1) cells of Lymnaea are located in the cerebral ganglia, and have axonal projections to the buccal ganglia. 2. Maintained depolarization of a CV1 neurone leads to initiation, maintenance and modulation of rhythmic feeding motor output from buccal and cerebral ganglia. 3. The CV1 cells receive rhythmic synaptic inputs, in phase with feeding cycles, which probably originate from buccal rhythm-generating interneurones. 4. CV1 cells initiate feeding cycles independently of the buccal slow oscillator (SO) neurone, previously described. The possible roles of CV1 and SO are discussed.

Serotonergic Modulation of Patterned Motor Output in Lymnaea Stagnalis

1988 ◽  
Vol 135 (1) ◽  
pp. 473-486
Author(s):  
M. D. TUERSLEY ◽  
C. R. McCROHAN
Keyword(s):  
Lymnaea Stagnalis ◽  
Rhythmic Activity ◽  
Motor Output ◽  
Buccal Ganglia ◽  
Apparent Decrease ◽  
Inactive Phase ◽  
The Mean ◽  
Timing Of Onset ◽  
Serotonergic Modulation ◽  
Stimulation Of

Rhythmic feeding motor output from the buccal ganglia of Lymnaea stagnalis was evoked by tonic depolarization of the pattern-initiating interneurone SO in the isolated central nervous system. Perfusion with 10−4moll−1 serotonin (5-HT) led to a reduction in frequency of the SO-driven rhythm, and in some cases rhythmic activity was completely blocked. The frequency reduction was predominantly due to an increase in duration of the ‘inactive’ phase of the rhythm. In a number of preparations, the normal buccal rhythm was replaced by an ‘atypical’ pattern of bursting in buccal motoneurones in the presence of 5.HT. This was characterized by the absence of one phase (N2) of interneuronal activity in the feeding pattern generator. Stimulation of the serotonergic giant cerebral interneurones (CGCs), to increase the mean spike frequency from 1.0 to 2.5 Hz, mimicked some of the effects of 5-HT perfusion. However, the timing of onset of CGC stimulation in relation to depolarization of SO was critical; prolonged activation of a CGC led to an apparent decrease in its effectiveness in suppressing the buccal rhythm.

Characterization of a novel nuclear envelope protein restricted to certain cell types

1988 ◽  
Vol 90 (2) ◽  
pp. 237-245
Author(s):  
J.M. Lord ◽  
J.A. Thick ◽  
C.M. Bunce ◽  
A.M. Taylor ◽  
P.H. Gallimore ◽  
...  
Keyword(s):  
Nuclear Envelope ◽  
Envelope Protein ◽  
Cell Types ◽  
Integral Membrane Protein ◽  
Nuclear Pores ◽  
Cellular Processes ◽  
Relationship Of ◽  
The Relationship ◽  
Insight Into

The monoclonal antibody AGF2.3 identifies a nuclear envelope protein that is restricted to certain cell types. In particular, this antigen shows a reduced level of expression during haemopoietic cell maturation. In this study, we have examined the relationship of this protein to known nuclear envelope proteins that have a similar molecular mass. Antigen extraction and immunoelectron microscope studies revealed that the AGF2.3 protein is an integral membrane protein present at both the inner and outer aspects of the nuclear envelope. The protein is not associated with nuclear pores and therefore is distinct from pore complex proteins. The AGF2.3 protein does not have ATPase activity. Therefore, this protein is also distinct from a myosin heavy chain-like ATPase that is associated with the nuclear envelope. The AGF2.3 antibody identifies a novel nuclear envelope protein. Further studies of the biochemical nature of the AGF2.3 protein should provide insight into novel cellular processes at the nuclear envelope relating to the lineage or maturation status of cells.

Patterns of activity and axonal projections of the cerebral giant cells of the snail, Lymnaea stagnalis

1980 ◽  
Vol 85 (1) ◽  
pp. 149-168
Author(s):  
C. R. McCrohan ◽  
P. R. Benjamin
Keyword(s):  
Lymnaea Stagnalis ◽  
Giant Cells ◽  
Firing Activity ◽  
Axonal Projections ◽  
Morphological Studies ◽  
Buccal Ganglia ◽  
Injection Techniques ◽  
Junction Coupling ◽  
Neural Unit ◽  
Electrophysiological Methods

1.The paired cerebral giant cells (CGCs) of Lymnaea were studied using electrophysiological and anatomical techniques. 2. A strong electrotonic junction coupling the CGCs is located in the buccal ganglia, several millimetres distal to the cell bodies. This leads to 1:1 spike activity in the two cells. 3. The CGCs receive phasic and tonic inputs which appear to be common to the two cells. Two types of phasic input are synchronous with synaptic input to feeding motoneurones in the buccal ganglia. 4. Morphological studies, using three separate dye injection techniques, confirm the axonal projections shown by electrophysiological methods. The CGCs project ipsilaterally into one lip nerve, the cerebrobuccal connective, and all buccal nerves. 5. Symmetry of anatomy and of firing activity cause the CGCs to function as a single neural unit.

Esophageal mechanoreceptors in the feeding system of the pond snail, Lymnaea stagnalis

1989 ◽  
Vol 61 (4) ◽  
pp. 727-736 ◽  
Author(s):  
C. J. Elliott ◽  
P. R. Benjamin
Keyword(s):  
Feeding Behavior ◽  
Synaptic Input ◽  
Lymnaea Stagnalis ◽  
Esophageal Wall ◽  
Pond Snail ◽  
Feeding System ◽  
Buccal Ganglia ◽  
Feeding Rhythm ◽  
Feeding Cycle ◽  
Stimulation Of

1. We identify esophageal mechanoreceptor (OM) neurons of Lymnaea with cell bodies in the buccal ganglia and axons that branch repeatedly to terminate in the esophageal wall. 2. The OM cells respond phasically to gut distension. Experiments with a high magnesium/low calcium solution suggest that the OM neurons are primary mechanoreceptors. 3. In the isolated CNS preparation, the OM cells receive little synaptic input during the feeding cycle. 4. The OM cells excite the motoneurons active in the rasp phase of the feeding cycle. 5. The OM cells inhibit each of the identified pattern-generating and modulatory interneurons in the buccal ganglia. Experiments with a saline rich in magnesium and calcium suggest that the connections are monosynaptic. 6. Stimulation of a single OM cell to fire at 5-15 Hz is sufficient to terminate the feeding rhythm in the isolated CNS preparation. 7. We conclude that these neurons play a role in terminating feeding behavior.

scholarly journals Imaging and Manipulating Pituitary Function in the Awake Mouse

Endocrinology ◽  
2019 ◽  
Vol 160 (10) ◽  
pp. 2271-2281 ◽  
Author(s):  
Ombeline Hoa ◽  
Chrystel Lafont ◽  
Pierre Fontanaud ◽  
Anne Guillou ◽  
Yasmine Kemkem ◽  
...  
Keyword(s):  
Pituitary Gland ◽  
Cell Types ◽  
Temporal Regulation ◽  
Hypothalamic Regulation ◽  
Health And Disease ◽  
Multiple Cell ◽  
Relationship Of ◽  
The Relationship ◽  
The Brain

Abstract Extensive efforts have been made to explore how the activities of multiple brain cells combine to alter physiology through imaging and cell-specific manipulation in different animal models. However, the temporal regulation of peripheral organs by the neuroendocrine factors released by the brain is poorly understood. We have established a suite of adaptable methodologies to interrogate in vivo the relationship of hypothalamic regulation with the secretory output of the pituitary gland, which has complex functional networks of multiple cell types intermingled with the vasculature. These allow imaging and optogenetic manipulation of cell activities in the pituitary gland in awake mouse models, in which both neuronal regulatory activity and hormonal output are preserved. These methodologies are now readily applicable for longitudinal studies of short-lived events (e.g., calcium signals controlling hormone exocytosis) and slowly evolving processes such as tissue remodeling in health and disease over a period of days to weeks.

scholarly journals Myelin Repair: From Animal Models to Humans

2021 ◽  
Vol 15 ◽  
Author(s):  
Myriam Cayre ◽  
Marie Falque ◽  
Océane Mercier ◽  
Karine Magalon ◽  
Pascale Durbec
Keyword(s):  
Animal Models ◽  
Cell Types ◽  
Experimental Models ◽  
Matrix Proteins ◽  
Oligodendrocyte Progenitor Cells ◽  
Myelin Repair ◽  
The Central Nervous System ◽  
Relationship Of ◽  
The Relationship

It is widely thought that brain repair does not occur, but myelin regeneration provides clear evidence to the contrary. Spontaneous remyelination may occur after injury or in multiple sclerosis (MS). However, the efficiency of remyelination varies considerably between MS patients and between the lesions of each patient. Myelin repair is essential for optimal functional recovery, so a profound understanding of the cells and mechanisms involved in this process is required for the development of new therapeutic strategies. In this review, we describe how animal models and modern cell tracing and imaging methods have helped to identify the cell types involved in myelin regeneration. In addition to the oligodendrocyte progenitor cells identified in the 1990s as the principal source of remyelinating cells in the central nervous system (CNS), other cell populations, including subventricular zone-derived neural progenitors, Schwann cells, and even spared mature oligodendrocytes, have more recently emerged as potential contributors to CNS remyelination. We will also highlight the conditions known to limit endogenous repair, such as aging, chronic inflammation, and the production of extracellular matrix proteins, and the role of astrocytes and microglia in these processes. Finally, we will present the discrepancies between observations in humans and in rodents, discussing the relationship of findings in experimental models to myelin repair in humans. These considerations are particularly important from a therapeutic standpoint.

Interactions of the slow oscillator interneuron with feeding pattern-generating interneurons in Lymnaea stagnalis

1985 ◽  
Vol 54 (6) ◽  
pp. 1412-1421 ◽  
Author(s):  
C. J. Elliott ◽  
P. R. Benjamin
Keyword(s):  
Motor System ◽  
Lymnaea Stagnalis ◽  
Pond Snail ◽  
Excitatory Synapses ◽  
Feeding System ◽  
Buccal Ganglion ◽  
Buccal Ganglia ◽  
Feeding Rhythm ◽  
The Right ◽  
Stimulation Of

We have used intracellular recording from groups of interneurons in the feeding system of the pond snail, Lymnaea stagnalis, to examine the connections of a modulatory interneuron, the slow oscillator (SO), with the network of pattern-generating interneurons (N1, N2, and N3). The SO is an interneuron whose axon branches solely within the buccal ganglia. There is only one such cell in each snail. In half the snails the cell body is in the right buccal ganglion and in the other half in the left buccal ganglion. Stimulation of either the SO or one of the N1 pattern-generating interneurons elicits the feeding rhythm, but of all the buccal neurons, only the SO can drive the feeding rhythm at the frequency seen in the intact snail. The SO makes reciprocal excitatory synapses with the N1 interneurons that drive the protraction of the radula. This ensures strong activation of the feeding system. The SO inhibits the N2 interneurons. Postsynaptic potentials evoked by stimulation of the SO facilitate without spike broadening in the SO. The SO is strongly inhibited by N2 and N3 interneurons, which are active during the retraction phase. This gates any excitatory inputs to the SO, probably preventing protraction of the radula while retraction is underway. The results support the idea of a single interneuron capable of driving a hierarchically organized motor system.

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