scholarly journals Counting on dis-inhibition: a circuit motif for interval counting and selectivity in the anuran auditory system

2015 ◽  
Vol 114 (5) ◽  
pp. 2804-2815 ◽  
Author(s):  
Richard Naud ◽  
Dave Houtman ◽  
Gary J. Rose ◽  
André Longtin
Keyword(s):  
Auditory System ◽  
Temporal Structure ◽  
Selective Inhibition ◽  
Inhibitory Neurons ◽  
Pulse Excitation ◽  
General Importance ◽  
Simple Connectivity ◽  
Parsimonious Model ◽  
Millisecond Range ◽  
Species Specific

Information can be encoded in the temporal patterning of spikes. How the brain reads these patterns is of general importance and represents one of the greatest challenges in neuroscience. We addressed this issue in relation to temporal pattern recognition in the anuran auditory system. Many species of anurans perform mating decisions based on the temporal structure of advertisement calls. One important temporal feature is the number of sound pulses that occur with a species-specific interpulse interval. Neurons representing this pulse count have been recorded in the anuran inferior colliculus, but the mechanisms underlying their temporal selectivity are incompletely understood. Here, we construct a parsimonious model that can explain the key dynamical features of these cells with biologically plausible elements. We demonstrate that interval counting arises naturally when combining interval-selective inhibition with pulse-per-pulse excitation having both fast- and slow-conductance synapses. Interval-dependent inhibition is modeled here by a simple architecture based on known physiology of afferent nuclei. Finally, we consider simple implementations of previously proposed mechanistic explanations for these counting neurons and show that they do not account for all experimental observations. Our results demonstrate that tens of millisecond-range temporal selectivities can arise from simple connectivity motifs of inhibitory neurons, without recourse to internal clocks, spike-frequency adaptation, or appreciable short-term plasticity.

scholarly journals Target Interneuron Preference in Thalamocortical Pathways Determines the Temporal Structure of Cortical Responses

2018 ◽  
Vol 29 (7) ◽  
pp. 2815-2831 ◽  
Author(s):  
Y Audrey Hay ◽  
Jérémie Naudé ◽  
Philippe Faure ◽  
Bertrand Lambolez
Keyword(s):  
Temporal Structure ◽  
Sensory Information ◽  
Response Duration ◽  
Cortical Response ◽  
Inhibitory Neurons ◽  
Thalamic Nuclei ◽  
Response Dynamics ◽  
Mean Field Model ◽  
Local Circuits ◽  
Feedforward Inhibition

Abstract Sensory processing relies on fast detection of changes in environment, as well as integration of contextual cues over time. The mechanisms by which local circuits of the cerebral cortex simultaneously perform these opposite processes remain obscure. Thalamic “specific” nuclei relay sensory information, whereas “nonspecific” nuclei convey information on the environmental and behavioral contexts. We expressed channelrhodopsin in the ventrobasal specific (sensory) or the rhomboid nonspecific (contextual) thalamic nuclei. By selectively activating each thalamic pathway, we found that nonspecific inputs powerfully activate adapting (slow-responding) interneurons but weakly connect fast-spiking interneurons, whereas specific inputs exhibit opposite interneuron preference. Specific inputs thereby induce rapid feedforward inhibition that limits response duration, whereas, in the same cortical area, nonspecific inputs elicit delayed feedforward inhibition that enables lasting recurrent excitation. Using a mean field model, we confirm that cortical response dynamics depends on the type of interneuron targeted by thalamocortical inputs and show that efficient recruitment of adapting interneurons prolongs the cortical response and allows the summation of sensory and contextual inputs. Hence, target choice between slow- and fast-responding inhibitory neurons endows cortical networks with a simple computational solution to perform both sensory detection and integration.

scholarly journals Broad frequency sensitivity and complex neural coding in the larval zebrafish auditory system

2020 ◽  
Author(s):  
Rebecca E. Poulsen ◽  
Leandro A. Sholz ◽  
Lena Constantin ◽  
Itia Favre-Bulle ◽  
Gilles C. Vanwalleghem ◽  
...  
Keyword(s):  
Auditory System ◽  
Neural Coding ◽  
Larval Fish ◽  
Temporal Structure ◽  
Frequency Discrimination ◽  
Single Frequency ◽  
Auditory Stimuli ◽  
Functional Clustering ◽  
Zebrafish Larvae ◽  
Auditory Systems

SUMMARYMost animals have complex auditory systems that identify salient features of the acoustic landscape to direct appropriate responses. In fish, these features include the volume, frequency, complexity, and temporal structure of auditory stimuli transmitted through water. Larval fish have simple brains compared to adults, but swim freely and depend on sophisticated sensory processing for survival. Zebrafish larvae, an important model for studying brain-wide neural networks, have thus far been found to possess a rudimentary auditory system, sensitive to a narrow range of frequencies and without evident sensitivity to auditory features that are salient and ethologically important to adult fish. Here, we have combined a novel method for delivering water-borne sounds, a diverse assembly of acoustic stimuli, and whole-brain calcium imaging to describe the responses of individual auditory neurons across the brains of zebrafish larvae. Our results reveal responses to frequencies ranging from 100Hz to 4kHz, with evidence of frequency discrimination from 100Hz to 2.5kHz. Frequency-selective neurons are located in numerous regions of the brain, and neurons responsive to the same frequency are spatially grouped in some regions. Using functional clustering, we identified categories of neurons that are selective for pure tones of a single frequency, white noise, the sharp onset of auditory stimuli, and stimuli involving a gradual crescendo. These results suggest a more nuanced auditory system than has previously been described in larval fish and provide insights into how a young animal’s auditory system can both function acutely and serve as the scaffold of a more complex adult system.

Astrocytic iNOS-Dependent Enhancement of Synaptic Release in Mouse Neocortex

2010 ◽  
Vol 103 (3) ◽  
pp. 1322-1328 ◽  
Author(s):  
Yossi Buskila ◽  
Yael Amitai
Keyword(s):  
Pyramidal Neurons ◽  
Brain Slices ◽  
Selective Inhibition ◽  
Inhibitory Neurons ◽  
Small Subset ◽  
Excitatory Synapses ◽  
Brain Areas ◽  
Synaptic Release ◽  
Cellular Source ◽  
Inos Inhibition

Nitric oxide (NO) has been recognized as an atypical neuronal messenger affecting synaptic transmission, but its cellular source has remained unresolved as the neuronal NO synthase isoform (nNOS) in brain areas such as the neocortex is expressed only by a small subset of inhibitory neurons. The involvement of the glial NOS isoform (iNOS) in modulating neuronal activity has been largely ignored because it has been accepted that this enzyme is regulated by gene induction following detrimental stimuli. Using acute brain slices from mouse neocortex and electrophysiology, we found that selective inhibition of iNOS reduced both spontaneous and evoked synaptic release. Moreover, iNOS inhibition partially prevented and reversed the potentiation of excitatory synapses in layer 2/3 pyramidal neurons. NOS enzymatic assay confirmed a small but reliable Ca2+-independent activity fraction, consistent with the existence of functioning iNOS in the tissue. Together these data point to astrocytes as a source for the nitrosative regulation of synaptic release in the neocortex.

Neurophysiologic Basis for Cochlear and Auditory Brainstem Implants

2001 ◽  
Vol 10 (2) ◽  
pp. 68-77 ◽  
Author(s):  
Aage R. Møller
Keyword(s):  
Cochlear Implants ◽  
Auditory System ◽  
Temporal Structure ◽  
Temporal Analysis ◽  
Auditory Brainstem ◽  
Speech Discrimination ◽  
Complex Sounds ◽  
Frequency Bands ◽  
Spectral Components ◽  
Auditory Brainstem Implants

The physiologic basis for cochlear and brainstem implants is discussed. It is concluded that the success of cochlear implants may be explained by assuming that the auditory system can adequately discriminate complex sounds, such as speech sounds, on the basis of their temporal structure when that is encoded in a few separate frequency bands to offer moderate separation of spectral components. The most important roles of the cochlea seems to be to prepare complex sounds for temporal analysis and to create separate channels through which information in different frequency bands is transmitted separately to higher nervous centers for decoding of temporal information. It is then pertinent to ask how many channels are needed. Because speech discrimination is very important, it is probably sufficient to use enough channels to separate formants from each other.

scholarly journals Attractor Decision Network with Selective Inhibition

2021 ◽  
Author(s):  
Pei-Hsien Liu ◽  
Chung-Chuan Lo ◽  
Kuo-An Wu
Keyword(s):  
Posterior Parietal Cortex ◽  
Energy Landscape ◽  
Theoretical Models ◽  
Selective Inhibition ◽  
Inhibitory Neurons ◽  
Trade Off ◽  
Recent Experimental Study ◽  
Attractor Model ◽  
Computational Ability ◽  
Speed Accuracy

The ability to decide swiftly and accurately in an urgent scenario is crucial for an organism's survival. The neural mechanisms underlying the perceptual decision and trade-off between speed and accuracy have been extensively studied in the past few decades. Among several theoretical models, the attractor neural network model has successfully captured both behavioral and neuronal data observed in many decision experiments. However, a recent experimental study revealed additional details that were not considered in the original attractor model. In particular, the study shows that the inhibitory neurons in the posterior parietal cortex of mice are as selective to decision making results as the excitatory neurons, whereas the original attractor model assumes the inhibitory neurons to be unselective. In this study, we investigate a more general attractor model with selective inhibition, and analyze in detail how the computational ability of the network changes with selectivity. We proposed a reduced model for the selective model, and showed that selectivity adds a time-varying component to the energy landscape. This time dependence of the energy landscape allows the selective model to integrate information carefully in initial stages, then quickly converge to an attractor once the choice is clear. This results in the selective model having a more efficient speed-accuracy trade-off that is unreachable by unselective models.

scholarly journals The ESKAPE mobilome contributes to the spread of antimicrobial resistance and CRISPR-mediated conflict between mobile genetic elements

2022 ◽  
Author(s):  
João Botelho ◽  
Adrian Cazares ◽  
Hinrich Schulenburg
Keyword(s):  
Antibiotic Resistance Genes ◽  
Distribution Patterns ◽  
Mobile Genetic Elements ◽  
Human Pathogens ◽  
Systematic Analysis ◽  
Genetic Elements ◽  
General Importance ◽  
Species Specific ◽  
Eskape Pathogens ◽  
Asymmetrically Distributed

Mobile genetic elements (MGEs) mediate the shuffling of genes among organisms. They contribute to the spread of virulence and antibiotic resistance genes in human pathogens, including the particularly problematic group of ESKAPE pathogens, such as Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter sp. Here, we performed the first systematic analysis of MGEs, including plasmids, prophages, and integrative and conjugative/mobilizable elements (ICEs/IMEs), in the ESKAPE pathogens. We characterized over 1700 complete ESKAPE genomes and found that different MGE types are asymmetrically distributed across these pathogens. While some MGEs are capable of exchanging DNA beyond the genus (and phylum) barrier, horizontal gene transfer (HGT) is mainly restricted by phylum or genus. We further observed that most genes on MGEs have unknown functions and show intricate distribution patterns. Moreover, AMR genes and anti-CRISPRs are overrepresented in the ESKAPE mobilome. Our results also underscored species-specific trends shaping the number of MGEs, AMR, and virulence genes across pairs of conspecific ESKAPE genomes with and without CRISPR-Cas systems. Finally, we found that CRISPR targets vary according to MGE type: while plasmid CRISPRs almost exclusively target other plasmids, ICEs/IME CRISPRs preferentially target ICEs/IMEs and prophages. Overall, our study highlights the general importance of the ESKAPE mobilome in contributing to the spread of AMR and mediating conflict among MGEs.

scholarly journals Coding of communication calls in the subcortical and cortical structures of the auditory system

2008 ◽  
pp. S149-S159
Author(s):  
D Šuta ◽  
J Popelář ◽  
J Syka
Keyword(s):  
Guinea Pig ◽  
Auditory System ◽  
Neural Coding ◽  
Neuronal Response ◽  
Broad Band ◽  
Response Patterns ◽  
Neuronal Responses ◽  
Communication Signals ◽  
Medial Geniculate ◽  
Species Specific

The processing of species-specific communication signals in the auditory system represents an important aspect of animal behavior and is crucial for its social interactions, reproduction, and survival. In this article the neuronal mechanisms underlying the processing of communication signals in the higher centers of the auditory system--inferior colliculus (IC), medial geniculate body (MGB) and auditory cortex (AC)--are reviewed, with particular attention to the guinea pig. The selectivity of neuronal responses for individual calls in these auditory centers in the guinea pig is usually low--most neurons respond to calls as well as to artificial sounds; the coding of complex sounds in the central auditory nuclei is apparently based on the representation of temporal and spectral features of acoustical stimuli in neural networks. Neuronal response patterns in the IC reliably match the sound envelope for calls characterized by one or more short impulses, but do not exactly fit the envelope for long calls. Also, the main spectral peaks are represented by neuronal firing rates in the IC. In comparison to the IC, response patterns in the MGB and AC demonstrate a less precise representation of the sound envelope, especially in the case of longer calls. The spectral representation is worse in the case of low-frequency calls, but not in the case of broad-band calls. The emotional content of the call may influence neuronal responses in the auditory pathway, which can be demonstrated by stimulation with time-reversed calls or by measurements performed under different levels of anesthesia. The investigation of the principles of the neural coding of species-specific vocalizations offers some keys for understanding the neural mechanisms underlying human speech perception.

scholarly journals Validation of Antibiotic Susceptibility Testing Guidelines in a Routine Clinical Microbiology Laboratory Exemplifies General Key Challenges in Setting Clinical Breakpoints

2014 ◽  
Vol 58 (7) ◽  
pp. 3921-3926 ◽  
Author(s):  
Michael Hombach ◽  
Patrice Courvalin ◽  
Erik C. Böttger
Keyword(s):  
Antibiotic Susceptibility ◽  
Susceptibility Testing ◽  
Clinical Microbiology Laboratory ◽  
Large Set ◽  
Antibiotic Susceptibility Testing ◽  
Wild Type ◽  
General Importance ◽  
Key Issues ◽  
Clinical Breakpoints ◽  
Species Specific

ABSTRACTThis study critically evaluated the new European Committee for Antimicrobial Susceptibility Testing (EUCAST) antibiotic susceptibility testing guidelines on the basis of a large set of disk diffusion diameters determined for clinical isolates. We report several paradigmatic problems that illustrate key issues in the selection of clinical susceptibility breakpoints, which are of general importance not only for EUCAST but for all guidelines systems, i.e., (i) the need for species-specific determinations of clinical breakpoints/epidemiological cutoffs (ECOFFs), (ii) problems arising from pooling data from various sources, and (iii) the importance of the antibiotic disk content for separating non-wild-type and wild-type populations.

scholarly journals Somatic HCN channels augment and speed up GABAergic basket cell input-output function in human neocortex

2021 ◽  
Author(s):  
Viktor Szegedi ◽  
Emoke Bakos ◽  
Szabina Furdan ◽  
Pal Barzo ◽  
Gabor Tamas ◽  
...  
Keyword(s):  
Human Brain ◽  
Signal Transmission ◽  
Inhibitory Neurons ◽  
Basket Cell ◽  
Mammalian Brain ◽  
Resting Membrane Potential ◽  
Hcn Channels ◽  
Cyclic Nucleotide Gated Channels ◽  
Speed Up ◽  
Species Specific

Neurons in the mammalian brain exhibit evolution-driven species-specific differences in their functional properties. Therefore, understanding the human brain requires unraveling the human neuron 'uniqueness' and how it contributes to the operation of specific neuronal circuits. We show here that a highly abundant type of inhibitory neurons in the neocortex, GABAergic parvalbumin-expressing basket cell (pv+BC), exhibits in the human brain a specific somatic leak current mechanism, which is absent in their rodent neuronal counterparts. Human pv+BC soma shows electric leak conductance mediated by hyperpolarization-activated cyclic nucleotide-gated channels. This leak conductance has depolarizing effects on the resting membrane potential and it accelerates the rise of synaptic potentials in the cell soma. The leak facilitates the human pv+BC input-to-output fidelity and shortens the action potential generation to excitatory inputs. This mechanism constitutes an adaptation that enhances signal transmission fidelity and speed in the common inhibitory circuit in the human but not in the rodent neocortex.

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