Action potentials

Most neurons in the vertebrate nervous system communicate through action potentials that are typically considered all-or-none events, thus conveying information in a digital manner. However, recent work has suggested the possibility of non-stereotypical, hybrid analog-digital spikes (analog spikes for short) that modulate synaptic transmission, blurring the line between analog and digital signaling. In this study, we consider a model of a binomial synapse, where the probability of vesicle release is determined by a product of two factors: a binary indicator of presynaptic spiking, and a contin

…their output on the level of single action poten

…information in a digital manner via action potentials. Yet, a detailed understanding of the advantages of digital communication in the brain is still lacking. In our study, we investigate synaptic transmission in terms of an optimization problem, where the space of solutions comprises the digital and the analog regime. We analyze a binomial synapse model connecting two neurons, where the probability of transmitter release, modeled by a transfer function, depends on the axonal membrane potential. We optimize the transfer f

Precise timing of action potentials is crucial for processing sensory information. Axonal length and propagation speed largely determine the time necessary for action potentials to reach postsynaptic neurons. Within the retina, retinal ganglion cell (RGC) axons form the retinal nerve fiber layer (RNFL), a highly organized layer with species-specific axonal arrangements. The human RNFL is characterized by unmyelinated axons, resulting in slow signal transmission, and by the presence of the fovea, a specialized region enabling high-resolution vision located temporally to the optic nerve head (i.

Individual neurons’ action potentials (APs) have a dynamic waveform, the shape of which differs by neuron subtype and species. In analyses of single-unit data, however, this waveform is reduced to a binary “all-or-nothing” event, with systems and cognitive neuroscience focusing on the number and timing of spike events. This analytical convenience has, in turn, resulted in computational theories of neural coding that assume binarity.Despite this assumption, a considerable body of evidence shows that AP waveforms exhibit systematic, within-neuron variation that may contribute additional informat

Maternal depression presents risks to both fetal and child development. While treating maternal depression with antidepressants during pregnancy can alleviate the condition, it also has implications for the development of the offspring. Our study aims to explore the impact of maternal depression and/or prenatal antidepressant treatment on offspring neuronal excitability.We implemented an animal model of maternal depression through chronic and unpredictable stress exposure. Mirtazapine served as the chosen antidepressant. Four experimental groups were used: no stress with vehicle, stress with v

…as it applies to neurons and reporting action potentials. Genetically encoded calcium indicators are incredibly versatile and particularly useful for both in vivo and in vitro research. Depending on the application and use of indicators, the desired properties can drastically change from being very bright, to a very strong signal, to having fast dynamics, or any combination of the three. However, there are several disadvantages to using existing red shifted calcium indicators, those limitations being

How the brain processes information to learn and form memories is still a widely unanswered question. To gain insights, neurons are studied under great effort in vivo. However, the applied methods often only enable monitoring subsets of neurons embedded in a complex network or lack spatiotemporal resolution for analysis on a single-cell level. In bottom-up neuroscience, small neural networks of reduced complexity are engineered by seeding primary rat neurons or human induced pluripotent stem cell derived neurons into polydimethylsiloxane microstructures on top of microelectrode arrays (MEAs) t

…Precise interaction of single-neuron activity and brain oscillations presumably play a critical role in this process. Here, we used human single-neuron recordings from an object-location memory task with separate periods for encoding and retrieval to analyze the timing of single-neuron activity in the medial temporal lobe relative to the local theta rhythm. 18 epilepsy patients participated in the task and contributed to 27 experimental sessions. We extracted single-neuron action potentials fro

Capsaicin (CAP), has undergone extensive research in recent years due to its potential for pain relief, attributed to triggering the activation of TRPV1 receptors, known to be sensitized in painful conditions. This study aims to investigate CAP role in pain therapy within hTRPV1-expressing cell systems, namely ND7/23-hTRPV1 and CHO-hTRPV1. ND7/23 transfection with hTRPV1 was conducted to generate a neuronal model mirroring dorsal root ganglion neurons physiology, involved in pain transmission. To ascertain its specificity to CAP, calcium imaging (CI) was performed. Additionally, automated patc

…From these examples, it appears that action potentials mediate some form of coordinated action, a timed event. From this perspective, spikes should not be seen simply as noisy implementations of underlying continuous signals (a sort of analog-

…is spike sorting, the assignment of action potentials (or spikes) to individual neurons. Current spike sorting algorithms, however, can be inaccurate and do not properly model uncertainty of spike assignments, therefore discarding information that could potentially improve decoding performance. Recent advances in high-channel-count probes like Neuropixels (NP) and extracellular analysis pipelines allow for extracting a rich set of spike features to direc

When a neuron breaks silence, it can emit action potentials in a number of patterns. Some responses are so sudden and intense that electrophysiologists felt the need to single them out, labeling action potentials emitted at a particularly high frequency with a metonym – bursts. Is there more to bursts than a figure of speech? After all, sudden bouts of high-frequency firing are expected to occur whenever inputs surge. In this talk, I will discuss the implications of seeing the neural code as having three syllables: silences, spikes and bursts. In particular, I will describe recent theoretical

…and convert these signals to outgoing action potentials which regulate immune system functions. Thus, reflex neural circuits maintain parameters of immunological physiology within a narrow range optimal for health. Advances in neuroscience and immunology using optogenetics, pharm

There is little consensus on the level of spatial complexity at which dendrites operate. On the one hand, emergent evidence indicates that synapses cluster at micrometer spatial scales. On the other hand, most modelling and network studies ignore dendrites altogether. This dichotomy raises an urgent question: what is the smallest relevant spatial scale for understanding dendritic computation? We have developed a method to construct compartmental models at any level of spatial complexity. Through carefully chosen parameter fits, solvable in the least-squares sense, we obtain accurate reduced co

…capacitance has been observed in reaction to physiological changes like neural swelling, but also in ageing and Alzheimer's disease. Importantly, according to theory, even small changes of the capacitance can affect neuronal signal processing, e.g. increase network

…However, in the brain action potentials propagate along axons to induce postsynaptic currents with different delays at many sites simultaneously. This fundamental computational mechanism evolves spatially to engage the neuron populations involved in brain functions. To identify and understand the spatial processing in brains, this workshop will focus on the spatial principles of brain dynamics that determine how action potentials and membrane currents propagate in the networks of neurons that brains are made of. We

…However, in the brain action potentials propagate along axons to induce postsynaptic currents with different delays at many sites simultaneously. This fundamental computational mechanism evolves spatially to engage the neuron populations involved in brain functions. To identify and understand the spatial processing in brains, this workshop will focus on the spatial principles of brain dynamics that determine how action potentials and membrane currents propagate in the networks of neurons that brains are made of. We

…However, in the brain action potentials propagate along axons to induce postsynaptic currents with different delays at many sites simultaneously. This fundamental computational mechanism evolves spatially to engage the neuron populations involved in brain functions. To identify and understand the spatial processing in brains, this workshop will focus on the spatial principles of brain dynamics that determine how action potentials and membrane currents propagate in the networks of neurons that brains are made of. We