scholarly journals Gastric and pyloric motor pattern control by a modulatory projection neuron in the intact crab Cancer pagurus

2011 ◽  
Vol 105 (4) ◽  
pp. 1671-1680 ◽  
Author(s):  
Ulrike B. S. Hedrich ◽  
Florian Diehl ◽  
Wolfgang Stein
Keyword(s):  
Motor Activity ◽  
Motor Pattern ◽  
Central Pattern Generators ◽  
Projection Neuron ◽  
Firing Frequency ◽  
Projection Neurons ◽  
Cycle Period ◽  
Gastric Mill

Neuronal release of modulatory substances provides motor pattern generating circuits with a high degree of flexibility. In vitro studies have characterized the actions of modulatory projection neurons in great detail in the stomatogastric nervous system, a model system for neuromodulatory influences on central pattern generators. Less is known about the activities and actions of modulatory neurons in fully functional and richly modulated network settings, i.e., in intact animals. It is also unknown whether their activities contribute to the motor patterns in different behavioral conditions. Here, we show for the first time the activity and effects of the well-characterized modulatory projection neuron 1 (MCN1) in vivo and compare them to in vitro conditions. MCN1 was always spontaneously active, typically in a rhythmic fashion with its firing being interrupted by ascending inhibitions from the pyloric motor circuit. Its activity contributed to pyloric motor activity, because 1) the cycle period of the motor pattern correlated with MCN1 firing frequency and 2) stimulating MCN1 shortened the cycle period while 3) lesioning of the MCN1 axon reduced motor activity. In addition, gastric mill motor activity was elicited for the duration of the stimulation. Chemosensory stimulation of the antennae moved MCN1 away from baseline activity by increasing its firing frequency. Following this increase, a gastric mill rhythm was elicited and the pyloric cycle period decreased. Lesioning the MCN1 axon prevented these effects. Thus modulatory projection neurons such as MCN1 can control the motor output in vivo, and they participate in the processing of exteroceptive sensory information in behaviorally relevant conditions.

scholarly journals State-dependent sensorimotor gating in a rhythmic motor system

2017 ◽  
Vol 118 (5) ◽  
pp. 2806-2818 ◽  
Author(s):  
Rachel S. White ◽  
Robert M. Spencer ◽  
Michael P. Nusbaum ◽  
Dawn M. Blitz
Keyword(s):  
Motor Activity ◽  
Motor System ◽  
Sensory Feedback ◽  
Activity Patterns ◽  
Motor Pattern ◽  
Projection Neuron ◽  
Projection Neurons ◽  
Gastric Mill ◽  
Sensory Regulation ◽  
Motor Circuits

Sensory feedback influences motor circuits and/or their projection neuron inputs to adjust ongoing motor activity, but its efficacy varies. Currently, less is known about regulation of sensory feedback onto projection neurons that control downstream motor circuits than about sensory regulation of the motor circuit neurons themselves. In this study, we tested whether sensory feedback onto projection neurons is sensitive only to activation of a motor system, or also to the modulatory state underlying that activation, using the crab Cancer borealis stomatogastric nervous system. We examined how proprioceptor neurons (gastropyloric receptors, GPRs) influence the gastric mill (chewing) circuit neurons and the projection neurons (MCN1, CPN2) that drive the gastric mill rhythm. During gastric mill rhythms triggered by the mechanosensory ventral cardiac neurons (VCNs), GPR was shown previously to influence gastric mill circuit neurons, but its excitation of MCN1/CPN2 was absent. In this study, we tested whether GPR effects on MCN1/CPN2 are also absent during gastric mill rhythms triggered by the peptidergic postoesophageal commissure (POC) neurons. The VCN and POC pathways both trigger lasting MCN1/CPN2 activation, but their distinct influence on circuit feedback to these neurons produces different gastric mill motor patterns. We show that GPR excites MCN1 and CPN2 during the POC-gastric mill rhythm, altering their firing rates and activity patterns. This action changes both phases of the POC-gastric mill rhythm, whereas GPR only alters one phase of the VCN-gastric mill rhythm. Thus sensory feedback to projection neurons can be gated as a function of the modulatory state of an active motor system, not simply switched on/off with the onset of motor activity. NEW & NOTEWORTHY Sensory feedback influences motor systems (i.e., motor circuits and their projection neuron inputs). However, whether regulation of sensory feedback to these projection neurons is consistent across different versions of the same motor pattern driven by the same motor system was not known. We found that gating of sensory feedback to projection neurons is determined by the modulatory state of the motor system, and not simply by whether the system is active or inactive.

Long-Term Expression of Two Interacting Motor Pattern-Generating Networks in the Stomatogastric System of Freely Behaving Lobster

1998 ◽  
Vol 79 (3) ◽  
pp. 1396-1408 ◽  
Author(s):  
Stefan Clemens ◽  
Denis Combes ◽  
Pierre Meyrand ◽  
John Simmers
Keyword(s):  
Motor Neurons ◽  
Motor Pattern ◽  
Burst Duration ◽  
Cycle Period ◽  
Gastric Mill ◽  
Pyloric Network ◽  
Freely Behaving ◽  
Stomatogastric System

Clemens, Stefan, Denis Combes, Pierre Meyrand, and John Simmers. Long-term expression of two interacting motor pattern-generating networks in the stomatogastric system of freely behaving lobster. J. Neurophysiol. 79: 1396–1408, 1998. Rhythmic movements of the gastric mill and pyloric regions of the crustacean foregut are controlled by two stomatogastric neuronal networks that have been intensively studied in vitro. By using electromyographic recordings from the European lobster, Homarus gammarus, we have monitored simultaneously the motor activity of pyloric and gastric mill muscles for ≤3 mo in intact and freely behaving animals. Both pyloric and gastric mill networks are almost continuously active in vivo regardless of the presence of food. In unfed resting animals kept under “natural-like” conditions, the pyloric network expresses the typical triphasic pattern seen in vitro but at considerably slower cycle periods (2.5–3.5 s instead of 1–1.5 s). Gastric mill activity occurs at mean cycle periods of 20–50 s compared with 5–10 s in vitro but may suddenly stop for up to tens of minutes, then restart without any apparent behavioral reason. When conjointly active, the two networks express a strict coupling that involves certain but not all motor neurons of the pyloric network. The posterior pyloric constrictor muscles, innervated by a total of 8 pyloric (PY) motor neurons, are influenced by the onset of each gastric mill medial gastric/lateral gastric(MG/LG) neuron powerstroke burst, and for one cycle, PY neuron bursts may attain >300% of their mean duration. However, the duration of activity in the lateral pyloric constrictor muscle, innervated by the unique lateral pyloric (LP) motor neuron, remains unaffected by this perturbation. During this period after gastric perturbation, LP neuron and PY neurons thus express opposite burst-to-period relationships in that LP neuron burst duration is independent of the ongoing cycle period, whereas PY neuron burst duration changes with period length. In vitro the same type of gastro-pyloric interaction is observed, indicating that it is not dependent on sensory inputs. Moreover, this interaction is intrinsic to the stomatogastric ganglion itself because the relationship between the two networks persists after suppression of descending inputs to the ganglion. Intracellular recordings reveal that thisgastro-pyloric interaction originates from the gastric MG and LG neurons of the gastric network, which inhibit the pyloric pacemaker ensemble. As a consequence, the pyloric PY neurons, which are inhibited by the pyloric dilator (PD) neurons of the pyloric pacemaker group, extend their activity during the time that PD neuron is held silent. Moreover, there is evidence for a pyloro-gastric interaction, apparently rectifying, from the pyloric pacemakers back to the gastric MG/LG neuron group.

Differential Activation of Projection Neurons by Two Sensory Pathways Contributes to Motor Pattern Selection

2009 ◽  
Vol 102 (5) ◽  
pp. 2866-2879 ◽  
Author(s):  
Ulrike B. S. Hedrich ◽  
Carmen R. Smarandache ◽  
Wolfgang Stein
Keyword(s):  
Motor Pattern ◽  
Projection Neuron ◽  
Projection Neurons ◽  
Gastric Mill ◽  
Stomatogastric Nervous System ◽  
Motor Patterns ◽  
Commissural Neurons ◽  
Sensory Pathways ◽  
Motor Circuits ◽  
Selection Of

Sensorimotor integration is known to occur at the level of motor circuits as well as in upstream interneurons that regulate motor activity. Here we show, using the crab stomatogastric nervous system (STNS) as a model, that different sensory systems affect the same set of projection neurons. However, they have qualitatively different effects on their activities (excitation vs. inhibition), and these differences contribute to the selection of motor patterns from multifunctional circuits. We compare the actions of the proprioceptive anterior gastric receptor (AGR) and the inferior ventricular (IV) neurons, which relay chemosensory information from the brain to the STNS, on modulatory commissural neurons 1 and 5 (MCN1 and MCN5) and commissural projection neuron 2 (CPN2) and their resulting actions on the gastric mill central pattern generating circuit in the stomatogastric ganglion. When stimulated, AGR and the IV neurons affect all three projection neurons but elicit distinct gastric mill rhythms. The effects of both sensory pathways on the projection neurons differ in the type of excitation provided to CPN2 and MCN5 (electrical vs. chemical) and the effect on MCN1 (direct inhibition by AGR vs. polysynaptic excitation by the IV neurons). The latter is functionally important because a restoration of MCN1 activity during the AGR rhythm made it more similar to that elicited by IV neuron stimulation. Our results thus support the hypothesis that sensory pathways activate different combinations of projection neurons to select distinct outputs from the same neuronal circuit.

Recruitment of a projection neuron determines gastric mill motor pattern selection in the stomatogastric nervous system of the crab, Cancer borealis

1994 ◽  
Vol 72 (4) ◽  
pp. 1451-1463 ◽  
Author(s):  
B. J. Norris ◽  
M. J. Coleman ◽  
M. P. Nusbaum
Keyword(s):  
Nervous System ◽  
Synaptic Input ◽  
Motor Pattern ◽  
Rhythmic Activity ◽  
Projection Neuron ◽  
Projection Neurons ◽  
Muscarinic Agonist ◽  
Gastric Mill ◽  
Stomatogastric Nervous System ◽  
Cancer Borealis

1. In the isolated stomatogastric nervous system of the crab Cancer borealis (Fig. 1), the muscarinic agonist oxotremorine elicits several distinct gastric mill motor patterns from neurons in the stomatogastric ganglion (STG; Fig. 2). Selection of a particular gastric mill rhythm is determined by activation of distinct projection neurons that influence gastric mill neurons within the STG. In this paper we identify one such neuron, called commissural projection neuron 2 (CPN2), whose rhythmic activity is integral in producing one form of the gastric mill rhythm. 2. There is a CPN2 soma and neuropilar arborization in each commissural ganglion (CoG). The CPN2 axon projects through the superior esophageal nerve (son) and the stomatogastric nerve (stn) to influence neurons in the STG (Figs. 3 and 4A). 3. CPN2 activity influences most of the gastric mill neurons in the STG. Specifically, CPN2 excites gastric mill neurons GM and LG (gastric mill and lateral gastric, respectively) and inhibits the dorsal gastric (DG), anterior median (AM), medial gastric (MG), and inferior cardiac (IC) neurons (Figs. 5 and 6). CPN2 also indirectly inhibits gastric mill neurons Int1 and VD (interneuron 1 and ventricular dilator neuron, respectively) through its activation of LG. The CPN2 excitatory effects are mediated at least partly via discrete excitatory postsynaptic potentials (EPSPs; Fig. 4B), whereas its inhibitory effects are produced via smooth hyperpolarizations. 4. Within the CoG, CPN2 receives excitatory synaptic input from the anterior gastric receptor neuron (AGR), a gastric mill proprioceptive sensory neuron (Fig. 7) and inhibitory synaptic input from the gastric mill interneuron, Int1 (Fig. 8). 5. During one form of the gastric mill rhythm, CPN2 fires rhythmically in time with the gastric mill motor pattern, whereas it is silent or fires weakly during other gastric mill rhythms (Fig. 9). 6. When CPN2 rhythmic activity is suppressed during a CPN2-influenced gastric mill rhythm, the gastric mill rhythm continues, but the pattern is altered (Fig. 10). Moreover, transiently stimulating CPN2 during any ongoing gastric mill motor pattern can reset the timing of that rhythm (Fig. 11). 7. Tonic activity in CPN2 is insufficient to elicit a gastric mill rhythm (Fig. 12). Phasic activity in CPN2 can elicit a gastric mill rhythm only in preparations in which gastric mill neurons are already in an excited state (Figs. 12 and 13). 8. CPN2 recruitment plays a pivotal role in determining the final form of the gastric mill rhythm.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals The Whisking Rhythm Generator: A Novel Mammalian Network for the Generation of Movement

2007 ◽  
Vol 97 (3) ◽  
pp. 2148-2158 ◽  
Author(s):  
Nathan P. Cramer ◽  
Ying Li ◽  
Asaf Keller
Keyword(s):  
Firing Rate ◽  
Serotonin Receptor ◽  
Central Pattern Generators ◽  
Rhythm Generator ◽  
Low Concentrations ◽  
Rhythmic Firing ◽  
Pattern Generators ◽  
Cortical Inputs

Using the rat vibrissa system, we provide evidence for a novel mechanism for the generation of movement. Like other central pattern generators (CPGs) that underlie many movements, the rhythm generator for whisking can operate without cortical inputs or sensory feedback. However, unlike conventional mammalian CPGs, vibrissa motoneurons (vMNs) actively participate in the rhythmogenesis by converting tonic serotonergic inputs into the patterned motor output responsible for movement of the vibrissae. We find that, in vitro, a serotonin receptor agonist, α-Me-5HT, facilitates a persistent inward current (PIC) and evokes rhythmic firing in vMNs. Within each motoneuron, increasing the concentration of α-Me-5HT significantly increases the both the magnitude of the PIC and the motoneuron's firing rate. Riluzole, which selectively suppresses the Na+ component of PICs at low concentrations, causes a reduction in both of these phenomena. The magnitude of this reduction is directly correlated with the concentration of riluzole. The joint effects of riluzole on PIC magnitude and firing rate in vMNs suggest that the two are causally related. In vivo we find that the tonic activity of putative serotonergic premotoneurons is positively correlated with the frequency of whisking evoked by cortical stimulation. Taken together, these results support the hypothesized novel mammalian mechanism for movement generation in the vibrissa motor system where vMNs actively participate in the rhythmogenesis in response to tonic drive from serotonergic premotoneurons.

The central nervous origin of the swimming motor pattern in embryos of Xenopus laevis

1982 ◽  
Vol 99 (1) ◽  
pp. 185-196 ◽  
Author(s):  
J. A. Kahn ◽  
A. Roberts
Keyword(s):  
Motor Activity ◽  
Similar Pattern ◽  
Sensory Feedback ◽  
Motor Nerve ◽  
Motor Pattern ◽  
Cycle Period ◽  
Phase Lag ◽  
Nerve Activity ◽  
Rhythmic Motor ◽  
Swimming Pattern

Rhythmic motor nerve activity was recorded in stage 37/38 Xenopus embryos paralysed with curare. The activity was similar to the swimming motor pattern in the following ways: cycle period (40–125 ms), alternation of activity on either side of a segment, rostro-caudal phase lag. Episodes of rhythmic motor activity could be evoked by stimuli that evoke swimming and inhibited by stimuli that normally inhibit swimming. On this basis we conclude that the swimming motor pattern is generated by a central nervous mechanism and is not dependent on sensory feedback. In addition to the swimming pattern, another pattern of motor activity (‘synchrony’) was sometimes recorded in curarized embryos. In this, the rhythmic bursts on either side of a segment occurred in synchrony, and the rhythm period (20–50 ms) was half that in swimming. This was probably not an artifact of curarization as there were indications of a similar pattern in uncurarized embryos. Its function remains unclear.

Vertebrate retinal ganglion cells are selected from competent progenitors by the action of Notch

Development ◽  
1995 ◽  
Vol 121 (11) ◽  
pp. 3637-3650 ◽  
Author(s):  
C.P. Austin ◽  
D.E. Feldman ◽  
J.A. Ida ◽  
C.L. Cepko
Keyword(s):  
Cell Fate ◽  
Ganglion Cells ◽  
Notch Pathway ◽  
Cell Types ◽  
Projection Neurons ◽  
Specific Cell ◽  
Vitro Assay ◽  
Notch Activity

The first cells generated during development of the vertebrate retina are the ganglion cells, the projection neurons of the retina. Although they are one of the most intensively studied cell types within the central nervous system, little is known of the mechanisms that determine ganglion cell fate. We demonstrate that ganglion cells are selected from a large group of competent progenitors that comprise the majority of the early embryonic retina and that differentiation within this group is regulated by Notch. Notch activity in vivo was diminished using antisense oligonucleotides or augmented using a retrovirally transduced constitutively active allele of Notch. The number of ganglion cells produced was inversely related to the level of Notch activity. In addition, the Notch ligand Delta inhibited retinal progenitors from differentiating as ganglion cells to the same degree as did activated Notch in an in vitro assay. These results suggest a conserved strategy for neurogenesis in the retina and describe a versatile in vitro and in vivo system with which to examine the action of the Notch pathway in a specific cell fate decision in a vertebrate.

scholarly journals Similarities and differences in circuit responses to applied Gly1-SIFamide and peptidergic (Gly1-SIFamide) neuron stimulation

2019 ◽  
Vol 121 (3) ◽  
pp. 950-972 ◽  
Author(s):  
Dawn M. Blitz ◽  
Andrew E. Christie ◽  
Aaron P. Cook ◽  
Patsy S. Dickinson ◽  
Michael P. Nusbaum
Keyword(s):  
Activity Patterns ◽  
Projection Neuron ◽  
Projection Neurons ◽  
Gastric Mill ◽  
Stomatogastric Nervous System ◽  
Cancer Borealis ◽  
Axon Terminals ◽  
Motor Circuits ◽  
Commissural Neuron ◽  
Functional Context

Microcircuit modulation by peptides is well established, but the cellular/synaptic mechanisms whereby identified neurons with identified peptide transmitters modulate microcircuits remain unknown for most systems. Here, we describe the distribution of GYRKPPFNGSIFamide (Gly1-SIFamide) immunoreactivity (Gly1-SIFamide-IR) in the stomatogastric nervous system (STNS) of the crab Cancer borealis and the Gly1-SIFamide actions on the two feeding-related circuits in the stomatogastric ganglion (STG). Gly1-SIFamide-IR localized to somata in the paired commissural ganglia (CoGs), two axons in the nerves connecting each CoG with the STG, and the CoG and STG neuropil. We identified one Gly1-SIFamide-IR projection neuron innervating the STG as the previously identified modulatory commissural neuron 5 (MCN5). Brief (~10 s) MCN5 stimulation excites some pyloric circuit neurons. We now find that bath applying Gly1-SIFamide to the isolated STG also enhanced pyloric rhythm activity and activated an imperfectly coordinated gastric mill rhythm that included unusually prolonged bursts in two circuit neurons [inferior cardiac (IC), lateral posterior gastric (LPG)]. Furthermore, longer duration (>30 s) MCN5 stimulation activated a Gly1-SIFamide-like gastric mill rhythm, including prolonged IC and LPG bursting. The prolonged LPG bursting decreased the coincidence of its activity with neurons to which it is electrically coupled. We also identified local circuit feedback onto the MCN5 axon terminals, which may contribute to some distinctions between the responses to MCN5 stimulation and Gly1-SIFamide application. Thus, MCN5 adds to the few identified projection neurons that modulate a well-defined circuit at least partly via an identified neuropeptide transmitter and provides an opportunity to study peptide regulation of electrical coupled neurons in a functional context. NEW & NOTEWORTHY Limited insight exists regarding how identified peptidergic neurons modulate microcircuits. We show that the modulatory projection neuron modulatory commissural neuron 5 (MCN5) is peptidergic, containing Gly1-SIFamide. MCN5 and Gly1-SIFamide elicit similar output from two well-defined motor circuits. Their distinct actions may result partly from circuit feedback onto the MCN5 axon terminals. Their similar actions include eliciting divergent activity patterns in normally coactive, electrically coupled neurons, providing an opportunity to examine peptide modulation of electrically coupled neurons in a functional context.

Central pattern generators in the brainstem and spinal cord: an overview of basic principles, similarities and differences

2019 ◽  
Vol 30 (2) ◽  
pp. 107-164 ◽  
Author(s):  
Inge Steuer ◽  
Pierre A. Guertin
Keyword(s):  
Spinal Cord ◽  
Animal Models ◽  
Central Pattern Generators ◽  
Basic Principles ◽  
Advanced Level ◽  
Motor Behaviors ◽  
Similarities And Differences ◽  
Pattern Generators

AbstractCentral pattern generators (CPGs) are generally defined as networks of neurons capable of enabling the production of central commands, specifically controlling stereotyped, rhythmic motor behaviors. Several CPGs localized in brainstem and spinal cord areas have been shown to underlie the expression of complex behaviors such as deglutition, mastication, respiration, defecation, micturition, ejaculation, and locomotion. Their pivotal roles have clearly been demonstrated although their organization and cellular properties remain incompletely characterized. In recent years, insightful findings about CPGs have been made mainly because (1) several complementary animal models were developed; (2) these models enabled a wide variety of techniques to be used and, hence, a plethora of characteristics to be discovered; and (3) organizations, functions, and cell properties across all models and species studied thus far were generally found to be well-preserved phylogenetically. This article aims at providing an overview for non-experts of the most important findings made on CPGs inin vivoanimal models,in vitropreparations from invertebrate and vertebrate species as well as in primates. Data about CPG functions, adaptation, organization, and cellular properties will be summarized with a special attention paid to the network for locomotion given its advanced level of characterization compared with some of the other CPGs. Similarities and differences between these networks will also be highlighted.

scholarly journals Tropomyosin and Myosin-II Cellular Levels Promote Actomyosin Ring Assembly in Fission Yeast

2010 ◽  
Vol 21 (6) ◽  
pp. 989-1000 ◽  
Author(s):  
Benjamin C. Stark ◽  
Thomas E. Sladewski ◽  
Luther W. Pollard ◽  
Matthew Lord
Keyword(s):  
Motor Activity ◽  
Atpase Activity ◽  
Fission Yeast ◽  
Actin Filaments ◽  
Myosin Ii ◽  
Bound State ◽  
Contractile Ring ◽  
Ring Assembly

Myosin-II (Myo2p) and tropomyosin are essential for contractile ring formation and cytokinesis in fission yeast. Here we used a combination of in vivo and in vitro approaches to understand how these proteins function at contractile rings. We find that ring assembly is delayed in Myo2p motor and tropomyosin mutants, but occurs prematurely in cells engineered to express two copies of myo2. Thus, the timing of ring assembly responds to changes in Myo2p cellular levels and motor activity, and the emergence of tropomyosin-bound actin filaments. Doubling Myo2p levels suppresses defects in ring assembly associated with a tropomyosin mutant, suggesting a role for tropomyosin in maximizing Myo2p function. Correspondingly, tropomyosin increases Myo2p actin affinity and ATPase activity and promotes Myo2p-driven actin filament gliding in motility assays. Tropomyosin achieves this by favoring the strong actin-bound state of Myo2p. This mode of regulation reflects a role for tropomyosin in specifying and stabilizing actomyosin interactions, which facilitates contractile ring assembly in the fission yeast system.

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