The Experts below are selected from a list of 225 Experts worldwide ranked by ideXlab platform
Donald S. Faber - One of the best experts on this subject based on the ideXlab platform.
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▪ REVIEW The Mauthner Cell: What Has It Taught Us?
2016Co-Authors: Steven J. Zottoli, Donald S. FaberAbstract:The Mauthner Cell (M-Cell) is one of the few identifiable neurons in the vertebrate central nervous system. The ability to locate the M-Cell, along with its inputs and outputs, has resulted in important findings in diverse areas of neurobiology including the molecular biology of neurons, synaptic and systems physiology, behav-ior, development, and neuroethology. The review provides a brief overview of the M-Cell and then focuses on recent studies applying state-of-the-art techniques to address new issues and revisit old ones. One advantage of this preparation is the ability to conduct multidisciplinary studies from the subCellular to be-havioral levels. For example, studies of activity-dependent changes in the strength of mixed electrotonic and chemical synapses on the M-Cell’s lateral dendrite in vivo have been correlated with changes in the probability of eliciting a fast startle response initiated by the M-Cell and its associated circuits. Similarly, it is now possible to image the activity of the M-Cell and its homologs while observing motor behavior in zebrafish larvae. These approaches will provide direct tests of the functional properties of complex neural networks. Moreover, molecular mechanisms that underlie neuronal development can be tested directly with this neuron and its segmental homologs, because these Cells occur in singular pairs at defined locations. Finally, after spinal cord injury, the M-Cell’s axon regenerates, but does not follow its original course, and the startle response gradually recovers. The accessibility of the M-Cell system offers the promise that strat
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Atypical properties of release and short-term depression at a specialized nicotinic synapse in the Mauthner Cell network
Journal of Experimental Biology, 2011Co-Authors: Simon Gelman, Charlotte L. Grove, Donald S. FaberAbstract:SUMMARY Many synapses exhibit temporally complex forms of activity-dependent short-term synaptic plasticity. The diversity of these phenomena reflects the evolutionary specialization of synapses within networks. We examined the properties of transmission and plasticity, in vivo , at an identified, specialized axo-axonic nicotinic synapse between the goldfish Mauthner Cell and one of its targets, the cranial relay neuron (CRN), using intraCellular paired recordings and low frequency (0.33–2 Hz) train stimulations. Depression of successive excitatory postsynaptic potentials (EPSPs), which dominates short-term plasticity, had two components. A fast component reduced the amplitude of EPSP 2 , to less than 50% of EPSP 1 . A slow component produced an additional 10–30% of amplitude reduction and developed with a time constant of tens of seconds. The latencies of the later depressed responses were ∼0.1 ms longer than that of EPSP 1 , suggesting a reduced release probability. The Ca 2+ chelators EGTA and BAPTA, injected presynaptically, reduced all EPSPs and slowed development of the second component of depression. Interestingly, spike broadening, produced by injecting K + channel blockers, reduced release, but accelerated the kinetics of the slow component. Finally, Ba 2+ in the external medium enhanced release, and reduced the first component and slowed the development of the second component of depression. Taken together, these last two results, which are in contrast to observations at other synapses, and the two-component depression suggest atypical release properties at the output synapses of the Mauthner Cell, which triggers an escape behavior. We suggest that the second component of depression provides an additional safety factor to prevent repetitive firing of the CRN.
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▪ REVIEW The Mauthner Cell: What Has It Taught Us?
2008Co-Authors: Steven J. Zottoli, Donald S. FaberAbstract:The Mauthner Cell (M-Cell) is one of the few identifiable neurons in the vertebrate central nervous system. The ability to locate the M-Cell, along with its inputs and outputs, has resulted in important findings in diverse areas of neurobiology including the molecular biology of neurons, synaptic and systems physiology, behav-ior, development, and neuroethology. The review provides 26 a brief overview of the M-Cell and then focuses on recent studies applying state-of-the-art techniques to address new issues and revisit old ones. One advantage of this preparation is the ability to conduct multidisciplinary studies from the subCellular to be-havioral levels. For example, studies of activity-dependent changes in the strength of mixed electrotonic and chemical synapses on the M-Cell’s lateral dendrite in vivo have been correlated with changes in the probability of eliciting a fast startle response initiated by the M-Cell and its associated circuits. Similarly, it is now possible to image the activity of the M-Cell and its homologs while observing motor behavior in zebrafish larvae. These approaches will provide direct tests of the functional properties of complex neural networks. Moreover, molecular mechanisms that underlie neuronal development can be tested directly with this neuron and its segmental homologs, because these Cells occur in singular pairs at defined locations
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Slow inhibitory potentials in the teleost Mauthner Cell.
Neuroscience, 2001Co-Authors: K. Hatta, Donald S. Faber, N. Ankri, Henri KornAbstract:Abstract In vivo recordings from Mauthner Cells in adult zebrafish (Danio rerio) and goldfish (Carassius auratus) preparations with potassium chloride filled electrodes revealed a new class of long-lasting synaptic events in these Cells. Their decay time constant ranged from 20 to 80 ms, which is about 20 times longer than that of previously identified fast glycinergic inhibitory postsynaptic potentials in this neuron. The average time to peak of these slow events ranged from 1 to 6 ms. We demonstrated that they are also inhibitory since (i) they were resistant to antagonists of the excitatory glutamatergic receptors; (ii) their amplitude was increased following chloride loading of the Mauthner Cell; (iii) their reversal potential was the same as that of fast, glycinergic inhibitory postsynaptic potentials; and (iv) they produced an inhibitory shunt of the Cell's membrane resistance. Furthermore, as with the fast inhibitory postsynaptic potentials, the decay time of the slow events is voltage dependent, increasing when the Mauthner Cell is depolarized. However, these inhibitory postsynaptic potentials had a different pharmacological profile to the fast glycinergic ones. That is, they persisted in the presence of strychnine at doses that abolished the fast ones and they were more sensitive to bicuculline. These data are compatible with the notion that these inhibitory postsynaptic potentials are mediated by activation of a different inhibitory receptor type, and may be GABAergic. In addition, the decay time constant of the fast inhibitory postsynaptic current was shorter than the first of the two components that contribute to the bi-exponential decay reported previously for miniature inhibitory postsynaptic currents in Mauthner Cells of larval zebrafish. This suggests developmental modifications and/or a switch in the assembly of glycine receptor subtypes. While amplitude distributions of the fast miniature inhibitory postsynaptic potentials recorded in the presence of tetrodotoxin generally could fit with a single Gaussian function, the amplitude histograms of slow miniature events were skewed, often with multiple nearly equally spaced peaks, consistent with the synchronous release of several quantal units. These previously undescribed slow unitary inhibitory postsynaptic potentials contribute to inhibitory synaptic noise recorded in the Mauthner Cells. Specifically, autocorrelation analysis revealed gamma-like rhythms (30–80 Hz) in each of two phases, characterized as “noisy” and “quiet”, and dominated by the fast and slow inhibitory postsynaptic potentials, respectively. The major frequencies of these two states were significantly different (i.e. around 90 and 40 Hz, respectively), suggesting that the fast and slow inhibitory postsynaptic potentials are derived from different inhibitory networks. Chloride-filled Mauthner Cells gradually hyperpolarized in the presence of tetrodotoxin, reflecting the effect of ongoing activity in the interneurons that produce the slow events. We conclude that this new class of inhibitory postsynaptic potentials contributes to the tonic inhibition which controls the Mauthner Cell's excitability. In physiological conditions, this regulatory influence is expressed as a continuous shunt of this neuron's input resistance and responsiveness to sensory inputs.
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review the Mauthner Cell what has it taught us
The Neuroscientist, 2000Co-Authors: Steven J. Zottoli, Donald S. FaberAbstract:The Mauthner Cell (M-Cell) is one of the few identifiable neurons in the vertebrate central nervous system. The ability to locate the M-Cell, along with its inputs and outputs, has resulted in important findings in diverse areas of neurobiology including the molecular biology of neurons, synaptic and systems physiology, behavior, development, and neuroethology. The review provides a brief overview of the M-Cell and then focuses on recent studies applying state-of-the-art techniques to address new issues and revisit old ones. One advantage of this preparation is the ability to conduct multidisciplinary studies from the subCellular to behavioral levels. For example, studies of activity-dependent changes in the strength of mixed electrotonic and chemical synapses on the M-Cell's lateral dendrite in vivo have been correlated with changes in the probability of eliciting a fast startle response initiated by the M-Cell and its associated circuits. Similarly, it is now possible to image the activity of the M-Cell...
Steven J. Zottoli - One of the best experts on this subject based on the ideXlab platform.
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Hypoxia Has a Lasting Effect on Fast-Startle Behavior of the Tropical Fish Haemulon plumieri
The Biological bulletin, 2019Co-Authors: Mayra A Sanchez-garcia, Steven J. Zottoli, Loretta M. RobersonAbstract:Anthropogenic activities and climate change have resulted in an increase of hypoxic conditions in nearshore ecosystems worldwide. Depending on the persistence of a hypoxic event, the survival of aquatic animals can be compromised. Temperate fish exposed to hypoxia display a reduction in the probability of eliciting startle responses thought to be important for escape from predation. Here we examine the effect of hypoxia on the probability of eliciting fast-startle responses (fast-starts) of a tropical fish, the white grunt (Haemulon plumieri), and whether hypoxia has a prolonged impact on behavior once the fish are returned to normoxic conditions. White grunts collected from the San Juan Bay Estuary in Puerto Rico were exposed to an oxygen concentration of 2.5 mg L-1 (40% dissolved oxygen). We found a significant reduction in auditory-evoked fast-starts that lasted for at least 24 hours after fish were returned to normoxic conditions. Accessibility to the neuronal networks that underlie startle responses was an important motivator for this study. Mauthner Cells are identifiable neurons found in most fish and amphibians, and these Cells are known to initiate fast-starts in teleost fishes. The assumption that most of the short-latency responses in this study are Mauthner Cell initiated provided the impetus to characterize the white grunt Mauthner Cell. The identification of the Cell provides a first step in understanding how low oxygen levels may impact a single Cell and its circuit and the behavior it initiates.
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▪ REVIEW The Mauthner Cell: What Has It Taught Us?
2016Co-Authors: Steven J. Zottoli, Donald S. FaberAbstract:The Mauthner Cell (M-Cell) is one of the few identifiable neurons in the vertebrate central nervous system. The ability to locate the M-Cell, along with its inputs and outputs, has resulted in important findings in diverse areas of neurobiology including the molecular biology of neurons, synaptic and systems physiology, behav-ior, development, and neuroethology. The review provides a brief overview of the M-Cell and then focuses on recent studies applying state-of-the-art techniques to address new issues and revisit old ones. One advantage of this preparation is the ability to conduct multidisciplinary studies from the subCellular to be-havioral levels. For example, studies of activity-dependent changes in the strength of mixed electrotonic and chemical synapses on the M-Cell’s lateral dendrite in vivo have been correlated with changes in the probability of eliciting a fast startle response initiated by the M-Cell and its associated circuits. Similarly, it is now possible to image the activity of the M-Cell and its homologs while observing motor behavior in zebrafish larvae. These approaches will provide direct tests of the functional properties of complex neural networks. Moreover, molecular mechanisms that underlie neuronal development can be tested directly with this neuron and its segmental homologs, because these Cells occur in singular pairs at defined locations. Finally, after spinal cord injury, the M-Cell’s axon regenerates, but does not follow its original course, and the startle response gradually recovers. The accessibility of the M-Cell system offers the promise that strat
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axon cap morphology of the sea robin prionotus carolinus Mauthner Cell is correlated with the presence of signature field potentials and a c type startle response
The Journal of Comparative Neurology, 2011Co-Authors: Steven J. Zottoli, Tina W Wong, Mark Agostini, Jason R MeyersAbstract:Studies on the Mauthner Cell (M-Cell) of goldfish, Carassius auratus, have facilitated our understanding of how sensory information is integrated in the hindbrain to initiate C-type fast startle responses (C-starts). The goldfish M-Cell initial segment/axon hillock is surrounded by a composite axon cap consisting of a central core and a peripheral zone covered by a glial Cell layer. The high resistivity of the axon cap results in “signature” field potentials recorded on activation of the M-Cell, allowing unequivocal physiological identification of the M-Cell and of its feedback and reciprocal inhibitory networks that are crucial in ensuring that only one M-Cell is active and that it fires only once. Phylogenetic mapping of axon cap morphology to muscle activity patterns and behavior predicts that teleost fishes that have a composite axon cap, like that of the goldfish, will perform C-start behavior with primarily unilateral muscle activity. We have chosen to study these predictions in the northern sea robin, Prionotus carolinus, a percomorph fish. Although sea robins have a very different phylogenetic position, body form, and habitat compared with the goldfish, they display the correlation of axon cap morphology to physiology and C-start behavior. Differences in response parameters suggest some evolutionary trade-offs in sea robin C-start behavior compared with that of the goldfish, but the correlations in morphology, physiology, and behavior are common features of both otophysan and nonotophysan teleosts. The M-Cell will continue to provide an unprecedented opportunity to study the evolution of a neural circuit in the context of behavior. J. Comp. Neurol. 519:1979–1998, 2011. © 2011 Wiley-Liss, Inc.
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▪ REVIEW The Mauthner Cell: What Has It Taught Us?
2008Co-Authors: Steven J. Zottoli, Donald S. FaberAbstract:The Mauthner Cell (M-Cell) is one of the few identifiable neurons in the vertebrate central nervous system. The ability to locate the M-Cell, along with its inputs and outputs, has resulted in important findings in diverse areas of neurobiology including the molecular biology of neurons, synaptic and systems physiology, behav-ior, development, and neuroethology. The review provides 26 a brief overview of the M-Cell and then focuses on recent studies applying state-of-the-art techniques to address new issues and revisit old ones. One advantage of this preparation is the ability to conduct multidisciplinary studies from the subCellular to be-havioral levels. For example, studies of activity-dependent changes in the strength of mixed electrotonic and chemical synapses on the M-Cell’s lateral dendrite in vivo have been correlated with changes in the probability of eliciting a fast startle response initiated by the M-Cell and its associated circuits. Similarly, it is now possible to image the activity of the M-Cell and its homologs while observing motor behavior in zebrafish larvae. These approaches will provide direct tests of the functional properties of complex neural networks. Moreover, molecular mechanisms that underlie neuronal development can be tested directly with this neuron and its segmental homologs, because these Cells occur in singular pairs at defined locations
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review the Mauthner Cell what has it taught us
The Neuroscientist, 2000Co-Authors: Steven J. Zottoli, Donald S. FaberAbstract:The Mauthner Cell (M-Cell) is one of the few identifiable neurons in the vertebrate central nervous system. The ability to locate the M-Cell, along with its inputs and outputs, has resulted in important findings in diverse areas of neurobiology including the molecular biology of neurons, synaptic and systems physiology, behavior, development, and neuroethology. The review provides a brief overview of the M-Cell and then focuses on recent studies applying state-of-the-art techniques to address new issues and revisit old ones. One advantage of this preparation is the ability to conduct multidisciplinary studies from the subCellular to behavioral levels. For example, studies of activity-dependent changes in the strength of mixed electrotonic and chemical synapses on the M-Cell's lateral dendrite in vivo have been correlated with changes in the probability of eliciting a fast startle response initiated by the M-Cell and its associated circuits. Similarly, it is now possible to image the activity of the M-Cell...
Henri Korn - One of the best experts on this subject based on the ideXlab platform.
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Slow inhibitory potentials in the teleost Mauthner Cell.
Neuroscience, 2001Co-Authors: K. Hatta, Donald S. Faber, N. Ankri, Henri KornAbstract:Abstract In vivo recordings from Mauthner Cells in adult zebrafish (Danio rerio) and goldfish (Carassius auratus) preparations with potassium chloride filled electrodes revealed a new class of long-lasting synaptic events in these Cells. Their decay time constant ranged from 20 to 80 ms, which is about 20 times longer than that of previously identified fast glycinergic inhibitory postsynaptic potentials in this neuron. The average time to peak of these slow events ranged from 1 to 6 ms. We demonstrated that they are also inhibitory since (i) they were resistant to antagonists of the excitatory glutamatergic receptors; (ii) their amplitude was increased following chloride loading of the Mauthner Cell; (iii) their reversal potential was the same as that of fast, glycinergic inhibitory postsynaptic potentials; and (iv) they produced an inhibitory shunt of the Cell's membrane resistance. Furthermore, as with the fast inhibitory postsynaptic potentials, the decay time of the slow events is voltage dependent, increasing when the Mauthner Cell is depolarized. However, these inhibitory postsynaptic potentials had a different pharmacological profile to the fast glycinergic ones. That is, they persisted in the presence of strychnine at doses that abolished the fast ones and they were more sensitive to bicuculline. These data are compatible with the notion that these inhibitory postsynaptic potentials are mediated by activation of a different inhibitory receptor type, and may be GABAergic. In addition, the decay time constant of the fast inhibitory postsynaptic current was shorter than the first of the two components that contribute to the bi-exponential decay reported previously for miniature inhibitory postsynaptic currents in Mauthner Cells of larval zebrafish. This suggests developmental modifications and/or a switch in the assembly of glycine receptor subtypes. While amplitude distributions of the fast miniature inhibitory postsynaptic potentials recorded in the presence of tetrodotoxin generally could fit with a single Gaussian function, the amplitude histograms of slow miniature events were skewed, often with multiple nearly equally spaced peaks, consistent with the synchronous release of several quantal units. These previously undescribed slow unitary inhibitory postsynaptic potentials contribute to inhibitory synaptic noise recorded in the Mauthner Cells. Specifically, autocorrelation analysis revealed gamma-like rhythms (30–80 Hz) in each of two phases, characterized as “noisy” and “quiet”, and dominated by the fast and slow inhibitory postsynaptic potentials, respectively. The major frequencies of these two states were significantly different (i.e. around 90 and 40 Hz, respectively), suggesting that the fast and slow inhibitory postsynaptic potentials are derived from different inhibitory networks. Chloride-filled Mauthner Cells gradually hyperpolarized in the presence of tetrodotoxin, reflecting the effect of ongoing activity in the interneurons that produce the slow events. We conclude that this new class of inhibitory postsynaptic potentials contributes to the tonic inhibition which controls the Mauthner Cell's excitability. In physiological conditions, this regulatory influence is expressed as a continuous shunt of this neuron's input resistance and responsiveness to sensory inputs.
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a nonrandom dynamic component in the synaptic noise of a central neuron
Proceedings of the National Academy of Sciences of the United States of America, 1997Co-Authors: Philippe Faure, Henri KornAbstract:Continuous segments of synaptic noise were recorded in vivo from teleost Mauthner Cells and were studied with the methods of nonlinear analysis. As in many central neurons, this ongoing activity is dominated by consecutive inhibitory postsynaptic potentials. Recurrence plots and first or third order Poincare maps combined with surrogate shuffling revealed nonrandom patterns consistent with the notion that synaptic noise is a continuously varying mixture of periodic and chaotic phases. Chaos was further demonstrated by the occurrence of unstable periodic orbits. The nonrandom component of the noise is reproducibly and persistently reduced when the level of background sound, a natural stimulus for networks afferent to the Mauthner Cell, is briefly elevated. These data are consistent with a model involving a reciprocally connected inhibitory network, presynaptic to the Mauthner Cell and its intrinsic properties. The presence of chaos in the inhibitory synaptic noise that regulates the excitability of the Mauthner Cell and its sensitivity to external stimuli suggests that it modulates this neuron’s function, namely to trigger a fast escape motor reaction following unexpected sensory information.
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Morphofunctional evidence for mature synaptic contacts on the Mauthner Cell of 52-hour-old zebrafish larvae
Neuroscience, 1997Co-Authors: Antoine Triller, Henri Korn, Philippe Rostaing, Pascal LegendreAbstract:Abstract In a previous study, miniature inhibitory synaptic events recorded in the Mauthner Cell of the 52-hour-old zebrafish larvae ( Brachydanio rerio ) were found to be mainly glycinergic. Their amplitude distribution was not Gaussian and it was proposed that their large amplitude variation might reflect the activation of immature synapses. However, ultrastructural studies of the synaptic contacts over the M-Cell soma of 52 h larvae described here, revealed that numerous synaptic contacts on this neuron are already mature at this developmental stage and that most of them already contain a single active zone. As in the adult goldfish, immunohistochemistry indicates the presence of both glycine- and GABA-immunoreactive boutons which establish synaptic contacts. We also found that, in addition to the predominant glycinergic postsynaptic inhibitory currents, some postsynaptic currents are also GABAergic since they are specifically inhibited by bicuculline (20 μ M). GABAergic miniature events (time to peak close to 0.8 ms and decay time-constant close to 4–5 ms) were only detected in the presence of 11.5 mM [KCl] o . Their amplitude distributions were well fitted by one, or at most two, Gaussian curves. Outside-out recordings showed one class of GABA receptors with a main conductance state of 23 pS. This indicates that the smallest GABAergic miniature inhibitory synaptic events correspond to the opening of 14–20 chloride channels Pre- and postsynaptic factors which contribute to the predominance of glycinergic synaptic currents over GABAergic ones in untreated preparations and to the striking differences between their frequencies and their respective amplitude distribution histograms are discussed with reference to the morphological characteristics of the mature synaptic endings impinging on this still developing neuron.
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a nonrandom dynamic component in the synaptic noise of a central neuron chaosyrecurrence plotyunstable periodic orbityauditory inputsyattention
1997Co-Authors: Philippe Faure, Henri KornAbstract:Continuous segments of synaptic noise were recorded in vivo from teleost Mauthner Cells and were studied with the methods of nonlinear analysis. As in many central neurons, this ongoing activity is dominated by consecutive inhibitory postsynaptic potentials. Recurrence plots and first or third order Poincaremaps combined with surrogate shuf- f ling revealed nonrandom patterns consistent with the notion that synaptic noise is a continuously varying mixture of periodic and chaotic phases. Chaos was further demonstrated by the occurrence of unstable periodic orbits. The nonrandom component of the noise is reproducibly and persistently reduced when the level of background sound, a natural stimulus for networks afferent to the Mauthner Cell, is brief ly elevated. These data are consistent with a model involving a reciprocally connected inhibitory network, presynaptic to the Mauthner Cell and its intrinsic properties. The presence of chaos in the inhibitory synaptic noise that regulates the excitability of the Mauthner Cell and its sensitivity to external stimuli suggests that it modulates this neuron's function, namely to trigger a fast escape motor reaction following unexpected sensory information.
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Origin and function of spiral fibers projecting to the goldfish Mauthner Cell
The Journal of comparative neurology, 1994Co-Authors: John W. Scott, Steven J. Zottoli, Nicholas P. Beatty, Henri KornAbstract:Two neuron types contact the Mauthner Cell (M Cell) in the axon cap, a specialized region of high electrical resistance surrounding the initial segment of the M Cell axon. One type produces a mixed electrical and chemical inhibition of the M Cell. The second sends axons into the central core of the axon cap, where they spiral around the initial segment making both conventional synapses and gap junction contacts. The origin and synaptic effects of these spiral fibers have not been studied previously. When goldfish M Cells were filled with Lucifer yellow, presynaptic spiral fibers were seen in the axon cap. These fibers could be traced back through the medial longitudinal fasciculus to their somata, near the contralateral fifth nerve motor nucleus. The same somata were labeled by horseradish peroxidase injected extraCellularly into the axon cap. Recordings were made in the axon cap and the M Cell after stimulation of hindbrain areas near the spiral fiber somata and axons. ExtraCellularly, a negative potential was observed close to the termination of the spiral fibers and termed the spiral fiber potential (SFP). IntraCellularly, a graded, short latency depolarization of the M Cell corresponded to the SFP and could cause the M Cell to spike. This depolarization did not shunt the membrane, indicating that it may be produced through gap junctions. IntraCellular responses to hindbrain stimulation also had a chloride-dependent, second component that shunted the membrane during paired-pulse testing. This inhibitory second component was probably evoked by Cells other than the spiral fiber Cells themselves.
Thomas G. Preuss - One of the best experts on this subject based on the ideXlab platform.
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Differential processing in modality-specific Mauthner Cell dendrites.
The Journal of physiology, 2017Co-Authors: Violeta Medan, Tuomo Mäki-marttunen, Julieta Sztarker, Thomas G. PreussAbstract:KEY POINTS The present study examines dendritic integrative processes that occur in many central neurons but have been challenging to study in vivo in the vertebrate brain. The Mauthner Cell of goldfish receives auditory and visual information via two separate dendrites, providing a privileged scenario for in vivo examination of dendritic integration. The results show differential attenuation properties in the Mauthner Cell dendrites arising at least partly from differences in cable properties and the nonlinear behaviour of the respective dendritic membranes. In addition to distinct modality-dependent membrane specialization in neighbouring dendrites of the Mauthner Cell, we report cross-modal dendritic interactions via backpropagating postsynaptic potentials. Broadly, the results of the present study provide an exceptional example for the processing power of single neurons. ABSTRACT Animals process multimodal information for adaptive behavioural decisions. In fish, evasion of a diving bird that breaks the water surface depends on integrating visual and auditory stimuli with very different characteristics. How do neurons process such differential sensory inputs at the dendritic level? For that, we studied the Mauthner Cells (M-Cells) in the goldfish startle circuit, which receive visual and auditory inputs via two separate dendrites, both accessible for in vivo recordings. We investigated whether electrophysiological membrane properties and dendrite morphology, studied in vivo, play a role in selective sensory processing in the M-Cell. The results obtained show that anatomical and electrophysiological differences between the dendrites combine to produce stronger attenuation of visually evoked postsynaptic potentials (PSPs) than to auditory evoked PSPs. Interestingly, our recordings showed also cross-modal dendritic interaction because auditory evoked PSPs invade the ventral dendrite (VD), as well as the opposite where visual PSPs invade the lateral dendrite (LD). However, these interactions were asymmetrical, with auditory PSPs being more prominent in the VD than visual PSPs in the LD. Modelling experiments imply that this asymmetry is caused by active conductances expressed in the proximal segments of the VD. The results obtained in the present study suggest modality-dependent membrane specialization in M-Cell dendrites suited for processing stimuli of different time domains and, more broadly, provide a compelling example of information processing in single neurons.
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Cellular Mechanisms of Cortisol-Induced Changes in Mauthner-Cell Excitability in the Startle Circuit of Goldfish.
Frontiers in neural circuits, 2017Co-Authors: Daniel R. Bronson, Thomas G. PreussAbstract:Predator pressure and olfactory cues (alarm substance) have been shown to modulate Mauthner Cell (M-Cell) initiated startle escape responses (C-starts) in teleost fish. The regulation of such adaptive responses to potential threats is thought to involve the release of steroid hormones such as cortisol. However, the mechanism by which cortisol may regulate M-Cell excitability is not known. Here, we used intrasomatic, in vivo recordings to elucidate the acute effects of cortisol on M-Cell membrane properties and sound evoked post-synaptic potentials (PSPs). Cortisol tonically decreased threshold current in the M-Cell within 10 min before trending towards baseline excitability over an hour later, which may indicate the involvement of non-genomic mechanisms. Consistently, current ramp injection experiments showed that cortisol increased M-Cell input resistance in the depolarizing membrane, i.e., by a voltage-dependent postsynaptic mechanism. Cortisol also increases the magnitude of sound-evoked M-Cell PSPs by reducing the efficacy of local feedforward inhibition (FFI). Interestingly, another pre-synaptic inhibitory network mediating prepulse inhibition (PPI) remained unaffected. Together, our results suggest that cortisol rapidly increases M-Cell excitability via a post-synaptic effector mechanism, likely a chloride conductance, which, in combination with its dampening effect on FFI, will modulate information processing to reach threshold. Given the central role of the M-Cell in initiating startle, these results are consistent with a role of cortisol in mediating the expression of a vital behavior.
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The Mauthner-Cell circuit of fish as a model system for startle plasticity.
Journal of Physiology-paris, 2014Co-Authors: Violeta Medan, Thomas G. PreussAbstract:The Mauthner-Cell (M-Cell) system of teleost fish has a long history as an experimental model for addressing a wide range of neurobiological questions. Principles derived from studies on this system have contributed significantly to our understanding at multiple levels, from mechanisms of synaptic transmission and synaptic plasticity to the concepts of a decision neuron that initiates key aspects of the startle behavior. Here we will review recent work that focuses on the neurophysiological and neuropharmacological basis for modifications in the M-Cell circuit. After summarizing the main excitatory and inhibitory inputs to the M-Cell, we review experiments showing startle response modulation by temperature, social status, and sensory filtering. Although very different in nature, actions of these three sources of modulation converge in the M-Cell network. Mechanisms of modulation include altering the excitability of the M-Cell itself as well as changes in excitatory and inhibitor drive, highlighting the role of balanced excitation and inhibition for escape decisions. One of the most extensively studied forms of startle plasticity in vertebrates is prepulse inhibition (PPI), a sensorimotor gating phenomenon, which is impaired in several information processing disorders. Finally, we review recent work in the M-Cell system which focuses on the Cellular mechanisms of PPI and its modulation by serotonin and dopamine.
Francisco R. Morales - One of the best experts on this subject based on the ideXlab platform.
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Mauthner Cell-Initiated Electromotor Behavior Is Mediated via NMDA and Metabotropic Glutamatergic Receptors on Medullary Pacemaker Neurons in a Gymnotid Fish
2013Co-Authors: Sebastián Curti, Francisco R. Morales, Atilio Falconi, Michel BordeAbstract:Weakly electric fish generate meaningful electromotor behaviors by specific modulations of the discharge of their medullary pacemaker nucleus from which the rhythmic command for each electric organ discharge (EOD) arises. Certain electromotor behaviors seem to involve the activation of specific neurotransmitter receptors on particular target Cells within the nucleus, i.e., on pacemaker or on relay Cells. This paper deals with the neural basis of the electromotor behavior elicited by activation of Mauthner Cells in Gymnotus carapo. This behavior consists of an abrupt and prolonged increase in the rate of the EOD. The effects of specific glutamate agonists and antagonists on basal EOD frequency and on EOD accelerations induced by Mauthner Cell activation were assessed. Injections of both ionotropic (AMPA, kainate, and NMDA) and metabotropic (trans-(�)-1-amino-1,3-cyclopentanedicarboxylic acid) glutamate agonists induced increases in EOD rate that were maximal when performed close to the soma of pacemaker Cells. In contrast, injections in the proximity of relay Cells were ineffective. Therefore, pacemaker neurons are probably endowed with diverse glutamate receptor subtypes, whereas relay Cells are probably not. The Mauthner Cell-evoked electromotor behavior was suppressed by injections of AP-5 and (�)-amino-4carboxy-methyl-phenylacetic acid, NMDA receptor and metabotropic glutamate receptor antagonists, respectively. Thus, this electromotor behavior relies on the activation of the NMDA and metabotropic glutamate receptor subtypes of pacemaker Cells. Our study gives evidence for the synergistic effects of NMDA and metabotropic receptor activation and shows how a simple circuit can produce specific electromotor outputs. Key words: glutamate receptors; NMDA; metabotropic; pacemaker; Mauthner Cell; electric organ discharge; electric fish; escape response Gymnotiform fish rhythmically emit electric organ discharges (EOD) for electrolocation and social communication (Lissman
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Mauthner Cell-initiated electromotor behavior is mediated via NMDA and metabotropic glutamatergic receptors on medullary pacemaker neurons in a gymnotid fish.
The Journal of neuroscience : the official journal of the Society for Neuroscience, 1999Co-Authors: Sebastián Curti, Francisco R. Morales, Atilio Falconi, Michel BordeAbstract:Weakly electric fish generate meaningful electromotor behaviors by specific modulations of the discharge of their medullary pacemaker nucleus from which the rhythmic command for each electric organ discharge (EOD) arises. Certain electromotor behaviors seem to involve the activation of specific neurotransmitter receptors on particular target Cells within the nucleus, i.e., on pacemaker or on relay Cells. This paper deals with the neural basis of the electromotor behavior elicited by activation of Mauthner Cells in Gymnotus carapo . This behavior consists of an abrupt and prolonged increase in the rate of the EOD. The effects of specific glutamate agonists and antagonists on basal EOD frequency and on EOD accelerations induced by Mauthner Cell activation were assessed. Injections of both ionotropic (AMPA, kainate, and NMDA) and metabotropic ( trans -(±)-1-amino-1,3-cyclopentanedicarboxylic acid) glutamate agonists induced increases in EOD rate that were maximal when performed close to the soma of pacemaker Cells. In contrast, injections in the proximity of relay Cells were ineffective. Therefore, pacemaker neurons are probably endowed with diverse glutamate receptor subtypes, whereas relay Cells are probably not. The Mauthner Cell-evoked electromotor behavior was suppressed by injections of AP-5 and (±)-amino-4-carboxy-methyl-phenylacetic acid, NMDA receptor and metabotropic glutamate receptor antagonists, respectively. Thus, this electromotor behavior relies on the activation of the NMDA and metabotropic glutamate receptor subtypes of pacemaker Cells. Our study gives evidence for the synergistic effects of NMDA and metabotropic receptor activation and shows how a simple circuit can produce specific electromotor outputs.
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Mauthner Cell-initiated abrupt increase of the electric organ discharge in the weakly electric fish Gymnotus carapo
Journal of Comparative Physiology A, 1995Co-Authors: A. Falconi, Madhuri Borde, A. Hernández-cruz, Francisco R. MoralesAbstract:Stimulation of the spinal cord of the electric fish Gymnotus carapo, evoked an abrupt increase in the discharge rate of the electric organ. At the maximum of this response, the rate increased an average of 26 ± 11.8%. The duration of the response was 4.9 ± 2.12 s; its latency was 10.4 ± 1.1 ms. Activation of the Mauthner axon played a decisive role in this phenomenon as indicated by the following: (1) recordings from the axon cap of the Mauthner Cell demonstrated that the response was evoked if the Mauthner axon was antidromically activated and (2) a response that was similar to that produced by spinal cord stimulation, was elicited by intraCellular stimulation of either Mauthner Cell. Stimulation of the eighth nerve could also increase the discharge rate of the electric organ. The effect was greater if a Mauthner Cell action potential was elicited. The findings described in the present report, indicate the existence of a functional connection between the Mauthner Cell and the electromotor system in Gymnotus carapo. This connection may function to enhance the electrolocative sampling of the environment during Mauthner-Cell mediated behaviors. This is a novel function for the Mauthner Cell.
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Electrophysiological characteristics of the Mauthner Cell of the weakly electric fish Gymnotus carapo
Brain Research, 1991Co-Authors: Madhuri Borde, A.e. Pereda, Francisco R. MoralesAbstract:Abstract The Mauthner Cell (M-Cell) of the ‘weakly electric fish’ Gymnotus carapo was investigated with electrophysiological techniques. The antidromic action potential, the recurrent inhibitory input and the posterior VIIIth nerve excitatory input in this Cell exhibited characteristics similar to those described in the goldfish. In addition, we found an excitatory input evoked by spinal stimulation at intensities subthreshold for M-Cell axons.