Groups Of Neurons Research Articles

Comprehensive analysis of the C. elegans connectome reveals novel circuits and functions of previously unstudied neurons.

Despite decades of research on the Caenorhabditis elegans nervous system based on an anatomical description of synaptic connectivity, the circuits underlying behavior remain incompletely described and the functions of many neurons are still unknown. Updated and more complete chemical and gap junction connectomes of both adult sexes covering the entire animal including the muscle end organ have become available recently. Here, these are analyzed to gain insight into the overall structure of the connectivity network and to suggest functions of individual neuron classes. Modularity analysis divides the connectome graph into 10 communities that can be correlated with broad categories of behavior. A significant role of the body wall musculature end organ is emphasized as both a site of significant information convergence and as a source of sensory input in a feedback loop. Convergence of pathways for multisensory integration occurs throughout the network-most interneurons have similar indegrees and outdegrees and hence disperse information as much as they aggregate it. New insights include description of a set of high degree interneurons connected by many gap junctions running through the ventral cord that may represent a previously unrecognized locus of information processing. There is an apparent mechanosensory and proprioceptive field covering the entire body formed by connectivity of the many mechanosensory neurons of multiple types to 2 interneurons with output connections across the nervous system. Several additional significant, previously unrecognized circuits and pathways are uncovered, some involving unstudied neurons. The insights are valuable for guiding theoretical investigation of network properties as well as experimental studies of the functions of individual neurons, groups of neurons, and circuits.

Effect of childhood epilepsy and antiepileptic drugs on visual evoked potential response and optical coherence tomography

BackgroundEpileptic seizures arise from an excessively synchronous and sustained discharge of a group of neurons. The single feature of all epileptic syndromes is a persistent increase of neuronal excitability. Visual affection in epileptic children could be attributed to the disease itself or the use of anti-epileptic drugs, these changes may involve abnormal electro-physiological response. This biphasic study, conducted at the neuro-pediatric clinic at neurology department, aimed to investigate effect of idiopathic childhood epilepsy per se on (1) visual evoked potential and (2) optical coherence tomography and effect of selected two antiepileptic medications on them. All subjects were exposed to visual evoked potential and only cooperative subjects exposed to ocular coherence tomography before and after anti-epileptic drugs and were followed up over 2 years.ResultsThe study included 50 newly diagnosed epileptic children and 50 healthy controls, the mean P100 latency in the right eyes of the control group was 110.4 ± 3.76ms, while in the patients group was 114.94 ± 12.81ms that showed significant difference between the two groups with p value (0.020). After 2 years of treatment by levetiracetam and valproate, the mean P100 latency of the right and left eyes in the valproate group was 112.34 ± 7.05 ms and 112.59 ± 5.2 ms, respectively, and it was 114.85 ± 10.39 ms and 116.14 ± 9.84 ms, respectively, in the valproate group, which showed insignificant difference between the two groups. The mean average of retinal nerve fiber layer thickness between patients and controls was significant in both right and left eyes with p value 0.002 and < 0.001, respectively. After 1 year of treatment by levetiracetam in the first group and valproate in the second group, there was no significant difference between the two groups neither regarding retinal nerve fiber layer thickness nor ganglion cell complex in both eyes.ConclusionsThere was prolonged latency in the epileptic children before starting anti-epileptic drugs more than the control group; also there was thinning of the retinal nerve fiber layer thickness and average part of the ganglion cell complex thickness more in the epileptic children than in the healthy controls.

Thermally induced neuronal plasticity in the hypothalamus mediates heat tolerance.

Heat acclimation is an adaptive process that improves physiological performance and supports survival in the face of increasing environmental temperatures, but the underlying mechanisms are not well understood. Here we identified a discrete group of neurons in the mouse hypothalamic preoptic area (POA) that rheostatically increase their activity over the course of heat acclimation, a property required for mice to become heat tolerant. In non-acclimated mice, peripheral thermoafferent pathways via the parabrachial nucleus activate POA neurons and mediate acute heat-defense mechanisms. However, long-term heat exposure promotes the POA neurons to gain intrinsically warm-sensitive activity, independent of thermoafferent parabrachial input. This newly gained cell-autonomous warm sensitivity is required to recruit peripheral heat tolerance mechanisms in acclimated animals. This pacemaker-like, warm-sensitive activity is driven by a combination of increased sodium leak current and enhanced utilization of the NaV1.3 ion channel. We propose that this salient neuronal plasticity mechanism adaptively drives acclimation to promote heat tolerance.

Pharyngeal mechanosensory neurons control food swallow in Drosophila melanogaster

As the early step of food ingestion, the swallow is under rigorous sensorimotor control. Nevertheless, the mechanisms underlying swallow control at a molecular and circuitry level remain largely unknown. Here, we find that mutation of the mechanotransduction channel genes nompC, Tmc, or piezo impairs the regular pumping rhythm of the cibarium during feeding of the fruit fly Drosophila melanogaster. A group of multi-dendritic mechanosensory neurons, which co-express the three channels, wrap the cibarium and are crucial for coordinating the filling and emptying of the cibarium. Inhibition of them causes difficulty in food emptying in the cibarium, while their activation leads to difficulty in cibarium filling. Synaptic and functional connections are detected between the pharyngeal mechanosensory neurons and the motor circuit that controls swallow. This study elucidates the role of mechanosensation in swallow, and provides insights for a better understanding of the neural basis of food swallow.

Pharyngeal mechanosensory neurons control food swallow in Drosophila melanogaster.

As the early step of food ingestion, the swallow is under rigorous sensorimotor control. Nevertheless, the mechanisms underlying swallow control at a molecular and circuitry level remain largely unknown. Here, we find that mutation of the mechanotransduction channel genes nompC, Tmc, or piezo impairs the regular pumping rhythm of the cibarium during feeding of the fruit fly Drosophila melanogaster. A group of multi-dendritic mechanosensory neurons, which co-express the three channels, wrap the cibarium and are crucial for coordinating the filling and emptying of the cibarium. Inhibition of them causes difficulty in food emptying in the cibarium, while their activation leads to difficulty in cibarium filling. Synaptic and functional connections are detected between the pharyngeal mechanosensory neurons and the motor circuit that controls swallow. This study elucidates the role of mechanosensation in swallow, and provides insights for a better understanding of the neural basis of food swallow.

Differential energetic profile of signal processing in central vestibular neurons.

Energetic aspects of neuronal activity have become a major focus of interest given the fact that the brain among all organs dominates the oxygen consumption. At variance with the importance of neuroenergetics, the knowledge about how electrical activity and metabolism is correlated in defined neuronal populations is still rather scarce. We have estimated the ATP consumption in the two physiologically well characterized populations of frog central vestibular neurons, with tonic and phasic firing patterns, respectively. These two distinct groups of neurons jointly process head/body movements detected by semicircular canal and otolith organs in the inner ear. The ATP consumption for maintenance of the resting membrane potential (Vr) and postsynaptic action potential (AP) generation was calculated based on the wealth of previously reported morpho-physiological features of these two neuronal types. Accordingly, tonic vestibular neurons require less ATP across the physiological activity range for these major processes, than phasic vestibular neurons, despite the considerably higher firing rates of the former subtype. However, since both neuronal subtypes are indispensable for the encoding and processing of the entire head/body motion dynamics, the higher energy demand of phasic neurons represents an obvious and necessary price to pay. Although phasic and tonic neurons form the respective core elements of the frequency-tuned vestibular pathways, both cellular components are cross-linked through feedforward and feedback side loops. The prominent influence of inhibitory tonic neurons in shaping the highly transient firing pattern of phasic neurons is cost-intensive and contributes to energy consumption for electrical activity in addition to the already extensive energy costs of signal processing by the very leaky phasic vestibular neurons. Despite the sparse production of action potentials by phasic vestibular neurons, the computation by this neuronal type dominates the ATP expense for processing head/body movements, which might have contributed to the late evolutionary arrival of this central neuronal element, dedicated to the encoding of highly dynamic motion profiles.

Preconfigured cortico-thalamic neural dynamics constrain movement-associated thalamic activity

Neural preconfigured activity patterns (nPAPs), conceptualized as organized activity parcellated into groups of neurons, have been proposed as building blocks for cognitive and sensory processing. However, their existence and function in motor networks have been scarcely studied. Here, we explore the possibility that nPAPs are present in the motor thalamus (VL/VM) and their potential contribution to motor-related activity. To this end, we developed a preparation where VL/VM multiunitary activity could be robustly recorded in mouse behavior evoked by primary motor cortex (M1) optogenetic stimulation and forelimb movements. VL/VM-evoked activity was organized as rigid stereotypical activity patterns at the single and population levels. These activity patterns were unable to dynamically adapt to different temporal architectures of M1 stimulation. Moreover, they were experience-independent, present in virtually all animals, and pairs of neurons with high correlations during M1-stimulation also presented higher correlations during spontaneous activity, confirming their preconfigured nature. Finally, subpopulations expressing specific M1-evoked patterns also displayed specific movement-related patterns. Our data demonstrate that the behaviorally related identity of specific neural subpopulations is tightly linked to nPAPs.

Impedance Analysis of Ultramicroelectrodes for Neural Stimulation

Most neural stimulation techniques rely on macroelectrodes, which generate electric fields that impact neuronal groups rather than specific neurons, often resulting in unintended side effects.1,2 Ultramicroelectrodes (UMEs) offer enhanced spatial resolution, holding promise for precise targeting of specific neurons to optimize therapeutic outcomes while mitigating adverse effects. However, ultramicroelectrodes present challenges. For example, delivery of required charge may require current densities that can damage the electrode or adjacent tissue. Impedance measurements of UMEs were conducted and analyzed to understand stimulation currents and potential damage to the electrodes and tissue. The measurement-model technique was used to identify the optimal frequency range for regression analysis, to quantify the stochastic error structure, and to identify inconsistencies with the Kramers-Kronig relations. Understanding of the error structure is vital for interpretation.3 The regressions were weighted using the inverse of the variance for the stochastic error structures, and quality of fits were determined by the weighted chi-square statistic. Process modeling was used to understand and characterize the underlying physical and chemical processes that occur at the electrode-electrolyte interface and electrode-tissue interface during neural stimulation. Constant-phase element (CPE) parameters, Q and alpha, corresponding to the behavior of the electrode-tissue interface, were obtained from this model. In addition, parameters associated with a capacitive loop were identified. Work is in progress to identify the origin of this loop. References (1) Otto, K. J.; Schmidt, C. E. Neuron-Targeted Electrical Modulation. Science. March 20, 2020, pp 1303–1304. https://doi.org/10.1126/science.abb0216. (2) Orazem, M. E.; Otto, K. J., Alexander, C. L., Electrochemistry in Action-Engineering the Neuronal Response to Electrical Microstimulation. Electrochemical Society Interface 2023, 32 (1), 40–42. https://doi.org/10.1149/2.F06231IF. (3) Orazem, M. E.; Agarwal, P.; Jansen, A. N.; Wojcik, P. T.; Garcia-Rubio, L. H. Development of Physico-Chemical Models for Electrochemical Impedance Spectroscopy. Electrochim Acta 1993, 38 (14), 1903–1911.

Model of the HVC neural network as a song motor in zebra finch.

The nucleus HVC within the avian song system produces crystalized instructions which lead to precise, learned vocalization in zebra finches (Taeniopygia guttata). This paper proposes a model of the HVC neural network based on the physiological properties of individual HVC neurons, their synaptic interactions calibrated by experimental measurements, as well as the synaptic signal into this region which triggers song production. This neural network model comprises of two major neural populations in this area: neurons projecting to the nucleus RA and interneurons. Each single neuron model of HVCRA is constructed with conductance-based ion currents of fast Na+ and K+ and a leak channel, while the interneuron model includes extra transient Ca2+ current and hyperpolarization-activated inward current. The synaptic dynamics is formed with simulated delivered neurotransmitter pulses from presynaptic cells and neurotransmitter receptor opening rates of postsynaptic neurons. We show that this network model qualitatively exhibits observed electrophysiological behaviors of neurons independent or in the network, as well as the importance of bidirectional interactions between the HVCRA neuron and the HVCI neuron. We also simulate the pulse input from A11 neuron group to HVC. This signal successfully suppresses the interneuron, which leads to sequential firing of projection neurons that matches measured burst onset, duration, and spike quantities during the zebra finch motif. The result provides a biophysically based model characterizing the dynamics and functions of the HVC neural network as a song motor, and offers a reference for synaptic coupling strength in the avian brain.

The E3 ubiquitin ligase RNF220 maintains hindbrain Hox expression patterns through regulation of WDR5 stability.

The spatial and temporal linear expression of Hox genes establishes a regional Hox code, which is crucial for the antero-posterior (A-P) patterning, segmentation, and neuronal circuit development of the hindbrain. RNF220, an E3 ubiquitin ligase, is widely involved in neural development via targeting of multiple substrates. Here, we found that the expression of Hox genes in the pons was markedly up-regulated at the late developmental stage (post-embryonic day E15.5) in Rnf220-/- and Rnf220+/- mouse embryos. Single-nucleus RNA sequencing (RNA-seq) analysis revealed different Hox de-repression profiles in different groups of neurons, including the pontine nuclei (PN). The Hox pattern was disrupted and the neural circuits were affected in the PN of Rnf220+/- mice. We showed that this phenomenon was mediated by WDR5, a key component of the TrxG complex, which can be polyubiquitinated and degraded by RNF220. Intrauterine injection of WDR5 inhibitor (WDR5-IN-4) and genetic ablation of Wdr5 in Rnf220+/- mice largely recovered the de-repressed Hox expression pattern in the hindbrain. In P19 embryonal carcinoma cells, the retinoic acid-induced Hox expression was further stimulated by Rnf220 knockdown, which can also be rescued by Wdr5 knockdown. In short, our data suggest a new role of RNF220/WDR5 in Hox pattern maintenance and pons development in mice.

The E3 ubiquitin ligase RNF220 maintains hindbrain Hox expression patterns through regulation of WDR5 stability

The spatial and temporal linear expression of Hox genes establishes a regional Hox code, which is crucial for the antero-posterior (A-P) patterning, segmentation, and neuronal circuit development of the hindbrain. RNF220, an E3 ubiquitin ligase, is widely involved in neural development via targeting of multiple substrates. Here, we found that the expression of Hox genes in the pons was markedly up-regulated at the late developmental stage (post-embryonic day E15.5) in Rnf220-/- and Rnf220+/- mouse embryos. Single-nucleus RNA sequencing (RNA-seq) analysis revealed different Hox de-repression profiles in different groups of neurons, including the pontine nuclei (PN). The Hox pattern was disrupted and the neural circuits were affected in the PN of Rnf220+/- mice. We showed that this phenomenon was mediated by WDR5, a key component of the TrxG complex, which can be polyubiquitinated and degraded by RNF220. Intrauterine injection of WDR5 inhibitor (WDR5-IN-4) and genetic ablation of Wdr5 in Rnf220+/- mice largely recovered the de-repressed Hox expression pattern in the hindbrain. In P19 embryonal carcinoma cells, the retinoic acid-induced Hox expression was further stimulated by Rnf220 knockdown, which can also be rescued by Wdr5 knockdown. In short, our data suggest a new role of RNF220/WDR5 in Hox pattern maintenance and pons development in mice.

A Concept-Value Network as a Brain Model.

This paper suggests a statistical framework for describing the relations between the physical and conceptual entities of a brain-like model. Features and concept instances are put into context, where the paper suggests that features may be the electrical wiring; although, chemical connections are also possible. With this idea, the actual length of the connection is important, because it is related to firing rates and neuron synchronization, but the signal type is less important. The paper then suggests that concepts are neuron groups that link feature sets and concept instances are determined by chemical signals from those groups. Therefore, features become the static horizontal framework of the neural system and concepts are vertically interconnected combinations of these. With regards to functionality, the neuron is then considered to be functional, and the more horizontal memory structures can even be glial. This would also suggest that features can be distributed entities and not concentrated to a single area. Another aspect could be signal 'breaks' that compartmentalise a pattern and may help with neural binding.

An infralimbic cortex neuronal ensemble encoded during learning attenuates fear generalization expression.

Generalization allows previous experience to adaptively guide behavior when conditions change. The infralimbic (IL) subregion of the ventral medial prefrontal cortex plays a known role in generalization processes, although mechanisms remain unclear. A basic physical unit of memory storage and expression in the brain are sparse, distributed groups of neurons known as ensembles (i.e., the engram). Here, we set out to determine whether neuronal ensembles established in the IL during learning contribute to generalized responses. Generalization was tested in male and female mice by presenting a novel, ambiguous, tone generalization stimulus following Pavlovian defensive (fear) conditioning. The first experiment was designed to test a role for IL in generalization using chemogenetic manipulations. Results show IL regulates defensive behavior in response to ambiguous stimuli. IL silencing led to a switch in defensive state, from vigilant scanning to generalized freezing, while IL stimulation reduced freezing in favor of scanning. Leveraging activity-dependent "tagging" technology (ArcCreER T2 x eYFP system), a neuronal ensemble, preferentially located in IL Layer 2/3, was associated with the generalization stimulus. Remarkably, in the identical discrete location, fewer reactivated neurons were associated with the generalization stimulus at the remote timepoint (30 days) following learning. When an IL neuronal ensemble established during learning was selectively chemogenetically silenced, generalization increased. Conversely, IL neuronal ensemble stimulation reduced generalization. Overall, these data identify a crucial role for IL in suppressing generalized responses. Further, an IL neuronal ensemble, formed during learning, functions to later attenuate the expression of generalization in the presence of ambiguous threat stimuli.

Lateralized nodose ganglia gene expression implicates cholecystokinin receptors in interoceptive reward signaling.

The vagus nerves are important carriers of sensory information from the viscera to the central nervous system. Emerging evidence suggests that sensory signaling through the right, but not the left, vagus nerve evokes striatal dopamine release and reinforces appetitive behaviors. However, the extent to which differential gene expression within vagal sensory neurons contributes to this asymmetric reward-related signaling remains unknown. Here, we use single-cell RNA sequencing to identify genes that are differentially expressed between the left and right nodose ganglia (NG) to identify candidate genes likely to contribute to vagus-mediated reward signaling. We find that a group of neurons expressing Chrna3 (nicotinic acetylcholine receptor subunit 3) and Cckar (cholecystokinin A receptor) is preferentially expressed in the right NG of both rats and mice. This result suggests that differential expression of gut-innervating nutrient sensors in NG neurons may contribute to asymmetric encoding of interoceptive rewards by the vagus nerves.

Adeno-associated viral tools to trace neural development and connectivity across amphibians.

Amphibians, by virtue of their phylogenetic position, provide invaluable insights on nervous system evolution, development, and remodeling. The genetic toolkit for amphibians, however, remains limited. Recombinant adeno-associated viral vectors (AAVs) are a powerful alternative to transgenesis for labeling and manipulating neurons. Although successful in mammals, AAVs have never been shown to transduce amphibian cells efficiently. We screened AAVs in three amphibian species-the frogs Xenopus laevis and Pelophylax bedriagae and the salamander Pleurodeles waltl-and identified at least two AAV serotypes per species that transduce neurons. In developing amphibians, AAVs labeled groups of neurons generated at the same time during development. In the mature brain, AAVrg retrogradely traced long-range projections. Our study introduces AAVs as a tool for amphibian research, establishes a generalizable workflow for AAV screening in new species, and expands opportunities for cross-species comparisons of nervous system development, function, and evolution.

Gap Junctions in Different Neuronal Groups Exert Different Effects on Sharp Wave-ripples of a Neuronal Network in CA1

Abstract Gap junctions are indispensable for achieving brain functions. The direct coupling between neurons connected by gap junctions may contribute to synchronization of neuronal firing and emergence of sharp wave-ripples(SWR), which affect brain functions such as memory consolidation. However, considering the heterogeneity of excitatory and inhibitory neurons, it is not quite clear whether gap junctions have the same effect on the emergence of SWR in network activity in different neuron types. In order to explore the above problems, we constructed a neuronal network located in CA1 region of hippocampus, which contains excitatory pyramidal cells, PV+BCs and axo-axonic cells. Taking into account diverse connections between neurons and properties of neurons, we investigated effects of gap junctions on SWR in different kinds of neuronal populations in the constructed network with chemical synaptic connections by neurodynamical modeling. Numerical results show that gap junctions within pyramidal neurons and PV+BCs promote the emergence of SWR, whereas gap junctions within axo-axonic cells suppress it. At the same time, it is revealed that gap junctions in axo-axonic cells play a dominant role in modulating SWR. We hope that these findings provide some inspiration for studies on neuronal heterogeneity and the enhancement of synchronicity of oscillations by gap junctions.

NeuroTD: A Time-Frequency Based Multimodal Learning Approach to Analyze Time Delays in Neural Activities.

Studying temporal features of neural activities is crucial for understanding the functions of neurons as well as underlying neural circuits. To this end, recent researches employ emerging techniques including calcium imaging, Neuropixels, depth electrodes, and Patch-seq to generate multimodal time-series data that depict the activities of single neurons, groups of neurons, and behaviors. However, challenges persist, including the analysis of noisy, high-sampling-rate neuronal data, and the modeling of temporal dynamics across various modalities. To address these challenges, we developed NeuroTD, a novel deep learning approach to align multimodal time-series datasets and infer cross-modality temporal relationships such as time delays or shifts. Particularly, NeuroTD integrates Siamese neural networks with frequency domain transformations and complex value optimization for inference. We applied NeuroTD to three multimodal datasets to (1) analyze electrophysiological (ephys) time series measured by depth electrodes, identifying time delays among neurons across various positions, (2) investigate neural activity and behavioral time series data derived from Neuropixels and 3D motion captures, establishing causal relationships between neural activities and corresponding behavioral activities, and (3) explore gene expression and ephys data of single neurons from Patch-seq, identifying gene expression signatures highly correlated with time shifts in ephys responses. Finally, NeuroTD is open-source at https://github.com/daifengwanglab/NeuroTD for general use.

Temporal resolution of spike coding in feedforward networks with signal convergence and divergence.

Convergent and divergent structures in the networks that make up biological brains are found across many species and brain regions at various spatial scales. Neurons in these networks fire action potentials, or "spikes", whose precise timing is becoming increasingly appreciated as large sources of information about both sensory input and motor output. While previous theories on coding in convergent and divergent networks have largely neglected the role of precise spike timing, our model and analyses place this aspect at the forefront. For a suite of stimuli with different timescales, we demonstrate that structural bottlenecks- small groups of neurons post-synaptic to network convergence - have a stronger preference for spike timing codes than expansion layers created by structural divergence. Additionally, we found that a simple network model based on convergence and divergence ratios of a hawkmoth (Manduca sexta) nervous system can reproduce the relative contribution of spike timing information in its motor output, providing testable predictions on optimal temporal resolutions of spike coding across the moth sensory-motor pathway at both the single-neuron and population levels. Our simulations and analyses suggest a relationship between the level of convergent/divergent structure present in a feedforward network and the loss of stimulus information encoded by its population spike trains as their temporal resolution decreases, which could be tested experimentally across diverse neural systems in future studies. We further show that this relationship can be generalized across different spike-generating models and measures of coding capacity, implying a potentially fundamental link between network structure and coding strategy using spikes.

Celsr3 drives development and connectivity of the acoustic startle hindbrain circuit.

In the developing brain, groups of neurons organize into functional circuits that direct diverse behaviors. One such behavior is the evolutionarily conserved acoustic startle response, which in zebrafish is mediated by a well-defined hindbrain circuit. While numerous molecular pathways that guide neurons to their synaptic partners have been identified, it is unclear if and to what extent distinct neuron populations in the startle circuit utilize shared molecular pathways to ensure coordinated development. Here, we show that the planar cell polarity (PCP)-associated atypical cadherins Celsr3 and Celsr2, as well as the Celsr binding partner Frizzled 3a/Fzd3a, are critical for axon guidance of two neuron types that form synapses with each other: the command-like neuron Mauthner cells that drive the acoustic startle escape response, and spiral fiber neurons which provide excitatory input to Mauthner cells. We find that Mauthner axon growth towards synaptic targets is vital for Mauthner survival. We also demonstrate that symmetric spiral fiber input to Mauthner cells is critical for escape direction, which is necessary to respond to directional threats. Moreover, we identify distinct roles for Celsr3 and Celsr2, as Celsr3 is required for startle circuit development while Celsr2 is dispensable, though Celsr2 can partially compensate for loss of Celsr3 in Mauthner cells. This contrasts with facial branchiomotor neuron migration in the hindbrain, which requires Celsr2 while we find that Celsr3 is dispensable. Combined, our data uncover critical and distinct roles for individual PCP components during assembly of the acoustic startle hindbrain circuit.

Cellular mechanisms of synchronized rhythmic burst generation in the ventromedial hypothalamus.

The ventromedial hypothalamus (VMH) plays an important role in feeding behavior and control of the sympathetic nervous system (SNS). The VMH includes a group of neurons that exhibit strong synchronized rhythmic burst firing (so-called VMH oscillation). This VMH oscillation is glucose inhibited, responsive to feeding-related peptides, and is functionally coupled to outputs of the SNS. However, the details of its rhythm generation and synchronization mechanisms are unknown. In the present study, we investigated cellular mechanisms of VMH oscillation by means of electrophysiological recordings and calcium imaging in juvenile rat slice preparations including the VMH. In the electrophysiological study, we performed membrane potential recording from neurons in the vicinity of pipettes for field potential recording. We found that the rhythmic bursts in the VMH were preserved in low Ca2+/high Mg2+ synaptic transmission blockade solution. During membrane hyperpolarization by current injection, the action potential was largely inhibited, but fluctuation of the membrane potential remained with a frequency similar to that at resting potential level. The electric VMH oscillation disappeared after application of either a gap junction blocker, carbenoxolone (100µM), or a persistent sodium channel blocker, riluzole (20µM). Membrane potentials and input resistances of rhythmic burst neurons in the VMH were not significantly changed during these manipulations. A calcium imaging study revealed that all VMH cells exhibiting synchronized rhythmic activity detected by intracellular calcium increases were silenced following the application of carbenoxolone. These results suggest that VMH oscillation arises from the activation of persistent sodium channels and coupling via gap junctions.