A review of cell-type specific circuit mechanisms underlying epilepsy

Epilepsy is a prevalent neurological disorder,yet its underlying mechanisms remain incompletely understood.Accu-mulated studies have indicated that epilepsy is characterized by abnormal neural circuits.Understanding the circuit mechanisms is crucial for comprehending the pathogenesis of epilepsy.With advances in tracing and modulating tools for neural circuits,some epileptic circuits have been uncovered.This comprehensive review focuses on the cir-cuit mechanisms underlying epilepsy in various neuronal subtypes,elucidating their distinct roles.Epileptic seizures are primarily characterized by the hyperactivity of glutamatergic neurons and inhibition of GABAergic neurons.How-ever,specific activated GABAergic neurons and suppressed glutamatergic neurons exacerbate epilepsy through pref-erentially regulating the activity of GABAergic neurons within epileptic circuits.Distinct subtypes of GABAergic neurons contribute differently to epileptic activities,potentially due to their diverse connection patterns.Moreover,identical GABAergic neurons may assume distinct roles in different stages of epilepsy.Both GABAergic neurons and glutamatergic neurons with long-range projecting fibers innervate multiple nuclei;nevertheless,not all of these circuits contribute to epileptic activities.Epileptic circuits originating from the same nuclei may display diverse con-tributions to epileptic activities,and certain glutamatergic circuits from the same nuclei may even exert opposing effects on epilepsy.Neuromodulatory neurons,including cholinergic,serotonergic,dopaminergic,and noradrenergic neurons,are also implicated in epilepsy,although the underlying circuit mechanisms remain poorly understood.These studies suggest that epileptic nuclei establish intricate connections through cell-type-specific circuits and play pivotal roles in epilepsy.However,there are still limitations in knowledge and methods,and further understanding of epileptic circuits is crucial,particularly in the context of refractory epilepsy.

Neural Circuit Mechanisms Involved in Animals’Detection of and Response to Visual Threat

Evading or escaping from predators is one of the most crucial issues for survival across the animal kingdom.The timely detection of predators and the initiation of appropriate fight-or-flight responses are innate capabilities of the nervous system.Here we review recent progress in our understanding of innate visually-triggered defensive behaviors and the underlying neural circuit mechanisms,and a comparison among vinegar flies,zebrafish,and mice is included.This overview covers the anatomical and functional aspects of the neural circuits involved in this process,including visual threat processing and identification,the selection of appropriate behavioral responses,and the initiation of these innate defensive behaviors.The emphasis of this review is on the early stages of this pathway,namely,threat identification from complex visual inputs and how behavioral choices are influenced by differences in visual threats.We also briefly cover how the innate defensive response is processed centrally.Based on these summaries,we discuss coding strategies for visual threats and propose a common prototypical pathway for rapid innate defensive responses.

Novel Fast Operating Moving Coil Actuator with Compensation Coil for HVDC Circuit Breakers

DC circuit breakers are major enabling components for multi-terminal HVDC systems.Their key design targets are operating speed and efficiency.This paper proposes a novel moving coil actuator using a compensation coil topology to operate mechanical circuit breakers.This topology aims to significantly improve the magnetic field saturation and reduce the system inductance,so that the operating speed is increased.Four possible connection methods for the compensation coils are proposed and analyzed using finite element modeling,ensuing simulation results are compared and discussed.The operating speed of the moving coil actuator with compensation coils is significantly improved compared with the original moving coil actuator.The moving coil actuator with compensation coils can open a distance of 5 mm within 2.8 ms and the peak efficiency is 47%.

Local neuronal circuits that may shape the discharge patterns of inferior collicular neurons

The discharge patterns of neurons in auditory centers encode information about sounds.However,few studies have focused on the synaptic mechanisms underlying the shaping of discharge patterns using intracellular recording techniques.Here,we investigated the discharge patterns of inferior collicular（IC）neurons using intracellular recordings to further elucidate the mechanisms underlying the shaping of discharge patterns.Under in vivo intracellular recording conditions,recordings were obtained from 66 IC neurons in 18 healthy adult mice（Mus musculus,Km）under free field-stimulation.Fiftyeight of these neurons fired bursts of action potentials（APs）to auditory stimuli and the remaining eight just generated local responses such as excitatory（n=4）or inhibitory（n=4）postsynaptic potentials.Based on the APs and subthreshold responses,the discharge patterns were classified into seven types：phasic（24/58,41.4%）,phasic burst（8/58,13.8%）,pauser（4/58,6.9%）,phasic-pauser（1/58,1.7%）,chopper（2/58,3.4%）,primary-like tonic（14/58,24.1%）and sound-induced inhibitory（5/58,8.6%）.We concluded that（1）IC neurons exhibit at least seven distinct discharge patterns;（2）inhibition participates in shaping the discharge pattern of most IC neurons and plays a role in sculpting the pattern,except for the primary-like tonic pattern which was not shapedby inhibition;and（3）local neural circuits are the likely structural basis that shapes the discharge patterns of IC neurons and can be formed either in the IC or in lower-level auditory structures.