The Experts below are selected from a list of 129 Experts worldwide ranked by ideXlab platform
Donald H Edwards - One of the best experts on this subject based on the ideXlab platform.
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mechanisms of serotonergic facilitation of a Command Neuron
Journal of Neurophysiology, 2007Co-Authors: Brian L Antonsen, Donald H EdwardsAbstract:The lateral giant (LG) Command Neuron of crayfish responds to an attack directed at the abdomen by triggering a single highly stereotyped escape tail flip. Experimentally applied serotonin (5-hydro...
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eLS - Modulatory and Command InterNeurons for Behaviour
Encyclopedia of Life Sciences, 2001Co-Authors: Donald H EdwardsAbstract:Modulatory Neurons change the properties of synapses and Neurons, and thereby change the excitability or performance of neural circuits. Command Neurons activate specific neural circuits that mediate discrete behaviour patterns. By operating on Command Neurons, on the inputs that excite them and on the circuits that they excite, modulatory Neurons can transform individual patterns of behaviour and ensembles of behaviour in an adaptive manner. Keywords: neuromodulation; stomatogastric nervous system; crustacea; spinal pattern generator; rhythmic motor pattern; reconfiguration; Command Neuron; mauthner Neuron; lamprey; sensorimotor integration
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fifty years of a Command Neuron the neurobiology of escape behavior in the crayfish
Trends in Neurosciences, 1999Co-Authors: Donald H Edwards, William J Heitler, Franklin B KrasneAbstract:Fifty years ago C.A.G.Wiersma established that the giant axons of the crayfish nerve cord drive tail-flip escape responses.The circuitry that includes these giant Neurons has now become one of the best-understood neural circuits in the animal kingdom. Although it controls a specialized behavior of a relatively simple animal, this circuitry has provided insights that are of general neurobiological interest concerning matters as diverse as the identity of the neural substrates involved in making behavioral decisions, the cellular bases of learning, subcellular Neuronal computation, voltage-gated electrical synaptic transmission and modification of neuromodulator actions that result from social experience.This work illustrates the value of studying a circuit of moderate, but tractable, complexity and known behavioral function.
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postsynaptic modulation of rectifying electrical synaptic inputs to the lg escape Command Neuron in crayfish
The Journal of Neuroscience, 1991Co-Authors: Donald H Edwards, William J Heitler, Esther M Leise, Russell A FrickeAbstract:The lateral giant (LG) tail-flip escape system of crayfish is organized to provide a massive convergence of mechanosensory inputs onto the LG Command Neuron through electrical synapses from both mechanosensory afferents and interNeurons. We used electrophysiological techniques to show that the connections between three major mechanosensory interNeurons and LG rectify, and that their inputs to LG can be reduced by postsynaptic depolarization and increased by postsynaptic hyperpolarization. The mechanosensory afferents and interNeurons are excited by sensory nerve shock, and the components of the resulting LG PSP can be similarly modulated by the same postsynaptic potential changes. Because these inputs are all made through electrical synapses, we conclude that they are rectifying connections, as well. To test the physical plausibility of this conclusion, we developed an electrical model of the rectifying connection between a mechanosensory interNeuron and LG, and found that it can reproduce all the qualitative features of the orthodromic and antidromic experimental responses. The ability of postsynaptic membrane potential to modulate inputs through rectifying electrical synapses is used in the escape system to enhance LG’s relative sensitivity to novel, phasic stimuli. Postsynaptic depolarization of LG produced by earlier inputs “reverse-biases” the rectifying input synapses and reduces their strength relative to times when LG is at rest.
Kevin M Collins - One of the best experts on this subject based on the ideXlab platform.
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presynaptic gαo goa 1 signals to depress Command Neuron excitability and allow stretch dependent modulation of egg laying in caenorhabditis elegans
bioRxiv, 2020Co-Authors: Bhavya Ravi, Jian Zhao, Sana I Chaudhry, Mattingly K Bartole, Richard J Kopchock, Christian Guijarro, Lijun Kang, Kevin M CollinsAbstract:Egg laying in the nematode worm Caenorhabditis elegans is a two-state behavior modulated by internal and external sensory input. We have previously shown that homeostatic feedback of embryo accumulation in the uterus regulates bursting activity of the serotonergic HSN Command Neurons that sustains the egg-laying active state. How sensory feedback of egg release signals to terminate the egg-laying active state is less understood. We find that Gαo, a conserved Pertussis Toxin-sensitive G protein, signals within HSN to inhibit egg-laying circuit activity and prevent entry into the active state. Gαo signaling hyperpolarizes HSN, reducing HSN Ca2+ activity and input onto the postsynaptic vulval muscles. Loss of inhibitory Gαo signaling uncouples presynaptic HSN activity from a postsynaptic, stretch-dependent homeostat, causing precocious entry into the egg-laying active state when only a few eggs are present in the uterus. Feedback of vulval opening and egg release activates the uv1 neuroendocrine cells which release NLP-7 neuropeptides which signal to inhibit egg laying through Gαo-independent mechanisms in the HSNs and Gαo-dependent mechanisms in cells other than the HSNs. Thus, neuropeptide and inhibitory Gαo signaling maintains a bi-stable state of electrical excitability that dynamically controls circuit activity in response to both external and internal sensory input to drive a two-state behavior output.
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Presynaptic Gαo (GOA-1) signaling depresses Command Neuron excitability to allow for stretch-dependent modulation of egg-laying behavior in C. elegans
bioRxiv, 2019Co-Authors: Bhavya Ravi, Jian Zhao, Sana I Chaudhry, Mattingly K Bartole, Christian Guijarro, Lijun Kang, Kevin M CollinsAbstract:Caenorhabditis elegans egg laying is a two-state behavior modulated by sensory input. Feedback of egg accumulation in the uterus drives activity of the serotonergic HSN Command Neurons to promote the active state, but how aversive sensory stimuli signal to inhibit egg laying is not well understood. We find the Pertussis Toxin-sensitive G protein, Gαo, signals in HSN to inhibit circuit activity and prolong the inactive behavior state. Gαo signaling hyperpolarizes HSN, reducing Ca2+ activity and input into the postsynaptic vulval muscles. Loss of inhibitory Gαo signaling uncouples presynaptic HSN activity from a postsynaptic, stretch-dependent homeostat, causing precocious entry into the egg-laying active state. NLP-7 neuropeptides signal to reduce egg laying both by inhibiting HSN and by activating Gαo in cells other than HSN. Thus, Gαo integrates diverse signals to maintain a bi-stable state of electrical excitability that dynamically controls circuit activity and behavior output in response to a changing environment.
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serotonin and neuropeptides are both released by the hsn Command Neuron to initiate caenorhabditis elegans egg laying
PLOS Genetics, 2019Co-Authors: Jacob C Brewer, Andrew C Olson, Kevin M Collins, Michael R KoelleAbstract:Neurons typically release both a small-molecule neurotransmitter and one or more neuropeptides, but how these two types of signal from the same Neuron might act together remains largely obscure. For example, serotonergic Neurons in mammalian brain express the neuropeptide Substance P, but it is unclear how this co-released neuropeptide might modulate serotonin signaling. We studied this issue in C. elegans, in which all serotonergic Neurons express the neuropeptide NLP-3. The serotonergic Hermaphrodite Specific Neurons (HSNs) are Command motor Neurons within the egg-laying circuit which have been shown to release serotonin to initiate egg-laying behavior. We found that egg-laying defects in animals lacking serotonin were far milder than in animals lacking HSNs, suggesting that HSNs must release other signal(s) in addition to serotonin to stimulate egg laying. While null mutants for nlp-3 had only mild egg-laying defects, animals lacking both serotonin and NLP-3 had severe defects, similar to those of animals lacking HSNs. Optogenetic activation of HSNs induced egg laying in wild-type animals, and in mutant animals lacking either serotonin or NLP-3, but failed to induce egg laying in animals lacking both. We recorded calcium activity in the egg-laying muscles of animals lacking either serotonin, NLP-3, or both. The single mutants, and to a greater extent the double mutant, showed muscle activity that was uncoordinated and unable to expel eggs. Specifically, the vm2 muscles cells, which are direct postsynaptic targets of the HSN, failed to contract simultaneously with other egg-laying muscle cells. Our results show that the HSN Neurons use serotonin and the neuropeptide NLP-3 as partially redundant co-transmitters that together stimulate and coordinate activity of the target cells onto which they are released.
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serotonin and neuropeptides are both released by the hsn Command Neuron to initiate c elegans egg laying
bioRxiv, 2018Co-Authors: Jacob C Brewer, Kevin M Collins, Michael R KoelleAbstract:Neurons typically release both a small molecule neurotransmitter and one or more neuropeptides, but how these two types of signal from the same Neuron might act together remains largely obscure. For example, serotonergic Neurons in mammalian brain express the neuropeptide Substance P, but it is unclear how serotonin signaling might be modulated by a coreleased neuropeptide. We studied this issue in C. elegans , in which all serotonergic Neurons express the neuropeptide NLP-3. The serotonergic Hermaphrodite Specific Neurons (HSNs) are Command motor Neurons within the egg-laying circuit that have previously been shown to release serotonin to initiate egg-laying behavior. We found that egg-laying defects in animals lacking serotonin were far milder than in animals lacking HSNs, suggesting that HSNs must release other signal(s) in addition to serotonin to stimulate egg laying. While null mutants for nlp-3 had only mild egg-laying defects, animals lacking both serotonin and NLP-3 had severe defects, like those of animals lacking HSNs. Optogenetic activation of HSNs induced egg laying in wild-type animals, or in mutant animals lacking either serotonin or NLP-3, but failed to induce egg laying in animals lacking both. We recorded calcium activity in the egg-laying muscles of animals lacking either serotonin, NLP-3, or both. The single mutants, and to a greater extent the double mutant, showed muscle activity that was uncoordinated and unable to expel eggs, such that the vm2 muscles cells that are direct postsynaptic targets of the HSN failed to contract simultaneously with other egg-laying muscle cells. Our results show that the HSN Neurons use serotonin and the neuropeptide NLP-3 as partially redundant cotransmitters that together stimulate and coordinate activity of the target cells onto which they are released.
Eytan Ruppin - One of the best experts on this subject based on the ideXlab platform.
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emerging Command Neuron circuitry in evolved autonomous agents
Neurocomputing, 2001Co-Authors: Tuvik Beker, Ranit Aharonov, Eytan RuppinAbstract:Abstract Using a novel approach of Evolutionary Artificial Neural Networks (EANNs), we demonstrate the spontaneous emergence of a Command Neuron as a robust feature in evolved neuro-controllers for autonomous agents. The significance of EANNs to computational neuroscience is discussed in view of the similarity to biological models.
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Emergence of Memory-Driven Command Neurons in Evolved Artificial Agents
Neural Computation, 2001Co-Authors: Ranit Aharonov-barki, Tuvik Beker, Eytan RuppinAbstract:Using evolutionary simulations, we develop autonomous agents controlled by artificial neural networks (ANNs). In simple lifelike tasks of foraging and navigation, high performance levels are attained by agents equipped with fully recurrent ANN controllers. In a set of experiments sharing the same behavioral task but differing in the sensory input available to the agents, we find a common structure of a Command Neuron switching the dynamics of the network between radically different behavioral modes. When sensory position information is available, the Command Neuron reflects a map of the environment, acting as a location-dependent cell sensitive to the location and orientation of the agent. When such information is unavailable, the Command Neuron's activity is based on a spontaneously evolving short-term memory mechanism, which underlies its apparent place-sensitive activity. A two-parameter stochastic model for this memory mechanism is proposed. We show that the parameter values emerging from the evolutionary simulations are near optimal; evolution takes advantage of seemingly harmful features of the environment to maximize the agent's foraging efficiency. The accessibility of evolved ANNs for a detailed inspection, together with the resemblance of some of the results to known findings from neurobiology, places evolved ANNs as an excellent candidate model for the study of structure and function relationship in complex nervous systems.
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ECAL - Spontaneous Evolution of Command Neurons, Place Cells and Memory Mechanisms in Autonomous Agents
Advances in Artificial Life, 1999Co-Authors: Ranit Aharonov-barki, Tuvik Beker, Eytan RuppinAbstract:Using evolutionary simulations, we develop autonomous agents controlled by artificial neural networks (ANNs). In simple lifelike tasks of foraging and navigation, high performance levels cire attained by agents equipped with fully-recurrent ANN controllers. Examining several experimental settings, differing in the sensory input available to the agents, we find a common structure of a "Command Neuron" switching the dynamics of the network between radically different behavioural modes. In some of the models the Command Neuron reflects a map of the environment, acting as a "place cell". In others it is based on a spontaneously evolving short-term memory mechanism. The resemblance to known findings from neurobiology places Evolved ANNs as an excellent candidate model for the study of structure and function relation in complex nervous systems.
Randolf Didomenico - One of the best experts on this subject based on the ideXlab platform.
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the motor output of the mauthner cell a reticulospinal Command Neuron
Brain Research, 1990Co-Authors: Jonathan Nissanov, Robert C Eaton, Randolf DidomenicoAbstract:Abstract We electrically stimulated individual Mauthner (M-) cells to determine their motor contribution to C-starts of swimming goldfish. In comparison with sensory-evoked C-starts, M-reflexes triggered by electrical stimulation of single M-cells were significantly weaker and less variable. Stage 1 turns were both longer in duration and smaller in angle for the M-reflex when compared with the sensory-evoked C-start. This translates to an average reduction of 22% in angular velocity during stage 1. Likewise, during stage 2, the distance moved by the fish was reduced by 15% and the absolute value of stage 2 turning angle was reduced by 47%. In addition, the normal mechanical or neural coupling between stages 1 and 2 appeared to be altered for the M-reflex. from this and our other recent studies, we conclude that there must be two primary groups of reticulospinal Neurons in the escape triggering network. The first group includes the M-cell and determines the initial left-right direction of the response and the extent of stage 1 angle. From previous EMG recordings we know that the second group of Neurons can fire within 5–15 ms (average, 9 ms) after the stage 1 cells. These determine the onset time and direction of stage 2. Together the coupling of the two primary groups results in the full propulsive force and turning flexibility of the C-start.
Brian L Antonsen - One of the best experts on this subject based on the ideXlab platform.
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mechanisms of serotonergic facilitation of a Command Neuron
Journal of Neurophysiology, 2007Co-Authors: Brian L Antonsen, Donald H EdwardsAbstract:The lateral giant (LG) Command Neuron of crayfish responds to an attack directed at the abdomen by triggering a single highly stereotyped escape tail flip. Experimentally applied serotonin (5-hydro...