Slow Adaptation Research Articles

METER: A Dynamic Concept Adaptation Framework for Online Anomaly Detection

Real-time analytics and decision-making require online anomaly detection (OAD) to handle drifts in data streams efficiently and effectively. Unfortunately, existing approaches are often constrained by their limited detection capacity and slow adaptation to evolving data streams, inhibiting their efficacy and efficiency in handling concept drift , which is a major challenge in evolving data streams. In this paper, we introduce METER, a novel dynamic concept adaptation framework that introduces a new paradigm for OAD. METER addresses concept drift by first training a base detection model on historical data to capture recurring central concepts , and then learning to dynamically adapt to new concepts in data streams upon detecting concept drift. Particularly, METER employs a novel dynamic concept adaptation technique that leverages a hypernetwork to dynamically generate the parameter shift of the base detection model, providing a more effective and efficient solution than conventional retraining or fine-tuning approaches. Further, METER incorporates a lightweight drift detection controller, underpinned by evidential deep learning, to support robust and interpretable concept drift detection. We conduct an extensive experimental evaluation, and the results show that METER significantly outperforms existing OAD approaches in various application scenarios.

An integrate-and-fire approach to Ca2+ signaling. Part II: Cumulative refractoriness

Inositol 1,4,5-trisphosphate-induced Ca2+ signaling is a second messenger system used by almost all eukaryotic cells. The agonist concentration stimulating Ca2+ signals is encoded in the frequency of a Ca2+ concentration spike sequence. When a cell is stimulated, the interspike intervals (ISIs) often show a distinct transient during which they gradually increase, a system property we refer to as cumulative refractoriness. We extend a previously published stochastic model to include the Ca2+ concentration in the intracellular Ca2+ store as a slow adaptation variable. This model can reproduce both stationary and transient statistics of experimentally observed ISI sequences. We derive approximate expressions for the mean and coefficient of variation of the stationary ISIs. We also consider the response to the onset of a constant stimulus and estimate the length of the transient and the strength of the adaptation of the ISI. We show that the adaptation sets the coefficient of variation in agreement with current ideas derived from experiments. Moreover, we explain why, despite a pronounced transient behavior, ISI correlations can be weak, as often observed in experiments. Finally, we fit our model to reproduce the transient statistics of experimentally observed ISI sequences in stimulated HEK cells. The fitted model is able to qualitatively reproduce the relationship between the stationary interval correlations and the number of transient intervals, as well as the strength of the ISI adaptation. We also find positive correlations in the experimental sequence that cannot be explained by our model.

Convergence Properties of the (μ/μI, λ)-ES on the Rastrigin Function.

The highly multimodal Rastrigin test function is analyzed by deriving a new aggregated progress rate measure. It is derived as a function of the residual distance to the optimizer by assuming normally distributed positional coordinates around the global optimizer. This assumption is justified for successful ES-runs operating with sufficiently slow step-size adaptation. The measure enables the investigation of further convergence properties. For moderately large mutation strengths a characteristic distance-dependent Rastrigin noise floor is derived. For small mutation strengths local attraction is analyzed and an escape condition is established. Both mutation strength regimes combined pose a major challenge optimizing the Rastrigin function, which can be counteracted by increasing the population size. Hence, a population scaling relation to achieve high global convergence rates is derived which shows good agreement with experimental data.

(Invited) self-Powered Multifunctional Sensing and Control for Smart Wearables and Human-Machine Interfaces

Robust, high-performance tactile sensors are critical for developing soft intelligent robotics, human-machine interfaces (HMI), and wearable electronics. However, it is challenging to fabricate soft tactile sensors capable of multifunctional sensing under both fast and slow response conditions in a simple and low-cost manner. In this talk, I will present our recent efforts in developing novel self-powered sensors and HMIs for wearables and intelligent controls. I will first introduce a textile-based tactile sensor capable of multifunctional sensing (covering both dynamic and static measurements) for personalized healthcare monitoring and soft robotic control. Inspired by human skin, the tactile sensor consists of a triboelectric nanogenerator sensing layer to mimic the function of fast-adapting (FA) mechanoreceptors and a piezoresistive sensing layer to achieve the functionality of slow-adapting (SA) mechanoreceptors. Then, I will demonstrate a self-powered breath sensor to monitor the health conditions of patients and provide daily assistance for severely disabled people to control electrical household appliances and other smart systems. The new system provides the advantages of high sensitivity, good stability, low cost, and ease of use.

Intentionally Slow Concentric Velocity Resistance Exercise and Strength Adaptations: A Meta-Analysis.

Hermes, MJ and Fry, AC. Intentionally slow concentric velocity resistance exercise and strength adaptations: a meta-analysis. J Strength Cond Res 37(8): e470-e484, 2023-Intentionally slow-velocity resistance exercise (ISVRE) is suggested by some to be equally or more effective than fast or traditional velocities for increasing muscular strength. The purpose of this meta-analysis was to assess the effect ISVRE has on strength adaptations compared with faster or traditional velocities, with subgroup analyses exploring age, sex, and training status as confounding factors on the influence of velocity on strength adaptation. Eligible studies (n = 24) were required to be chronic (multiple weeks) randomized or nonrandomized comparative studies using dynamic constant external resistance for training and testing, and pre-post strength assessments. All studies examined healthy individuals (n = 625; fast or traditional n = 306, intentionally slow n = 319). A random-effects meta-analysis indicated a significant (p ≤ 0.05) effect in favor of fast training (effect size [ES] = 0.21, 95% confidence interval [CI] = 0.02-0.41, p = 0.03). Publication bias was noted through trim and fill analysis, with an adjusted effect size estimate of 0.32 (p < 0.001). Subgroup analyses indicated no difference between trained and untrained subjects (QM = 0.01, p = 0.93), and no difference between older and younger subgroups (QM = 0.09, p = 0.77), despite younger favoring faster (ES = 0.23, p = 0.049) and older not favoring either velocity (ES = 0.16, p = 0.46). Subgroup analysis also indicated women favored faster training (ES = 0.95, p < 0.001) in comparison to men (ES = 0.08, p = 0.58). Contrary to some previous reviews, these results indicate that chronic fast or traditional velocity resistance exercise increases muscular strength to a greater degree than ISVRE training. Resistance training velocity must be considered if strength is a desired outcome.

Conformable fractional-order derivative based adaptive FitzHugh-Nagumo neuron model

Abstract Various neuron models have been proposed and are extensively examined in the scientific literature. The FitzHugh-Nagumo neuron model is one of the most well-known and studied models. The FitzHugh-Nagumo model is not biologically consistent but operationally simple. A fractional-order derivative is described as a derivative with a non-integer order. Caputo, Grünwald-Letnikov, and Riemann-Liouville are some of the well-known fractional order derivatives. However, a simple fractional-order derivative called the conformable fractional-order derivative has been proposed in the literature and it is much simpler to use. In literature, there are already neuron models with fractional-order derivatives. In this study, a FitzHugh-Nagumo model circuit with a conformable fractional derivative capacitor and conformable fractional derivative inductor is proposed. The proposed circuit is modelled, and its simulation results are given. The simulation results reveal that the model circuit shows both slow and fast adaptation in firing frequency under sustained current stimulation.

Bio‐Inspired Artificial Fast‐Adaptive and Slow‐Adaptive Mechanoreceptors With Synapse‐Like Functions

AbstractDevelopment of artificial mechanoreceptors capable of sensing and pre‐processing external mechanical stimuli is a crucial step toward constructing neuromorphic perception systems that can learn and store information. Here, bio‐inspired artificial fast‐adaptive (FA) and slow‐adaptive (SA) mechanoreceptors with synapse‐like functions are demonstrated for tactile perception. These mechanoreceptors integrate self‐powered piezoelectric pressure sensors with synaptic electrolyte‐gated field‐effect transistors (EGFETs) featuring a reduced graphene oxide channel. The FA pressure sensor is based on a piezoelectric poly(vinylidene fluoride‐trifluoroethylene) (P(VDF‐TrFE)) thin film, while the SA pressure sensor is enabled by a piezoelectric ionogel with the piezoelectric‐ionic coupling effect based on P(VDF‐TrFE) and an ionic liquid. Changes in post‐synaptic current are achieved through the synaptic effect of the EGFET by regulating the amplitude, number, duration, and frequency of tactile stimuli (pre‐synaptic pulses). These devices have great potential to serve as artificial biological mechanoreceptors for future artificial neuromorphic perception systems.

The Continuing Influence of the COVID-19 Pandemic on Tertiary Education

We are pleased to publish the first regular issue (Volume 13, Issue 1) of &lt;em&gt;Higher Learning Research Communications (HLRC)&lt;/em&gt; for 2023. While the World Health Organization and the governments and health departments in most of the world have ended the COVID-19 emergency, the effects of the pandemic on operations in higher education will likely continue for some time. The United Nations Educational, Scientific and Cultural Organization (UNESCO) published a report (Abdrasheva, 2022) that globally examines the state of higher education two years after the pandemic began. The authors noted that in the area of teaching and learning, “slow adaptation to online tools, preparing class material, and engaging students to actively participate while being remote” (p. 6) resulted in uneven quality of instruction. They also note that in areas affected by the digital divide, these shortcomings were much more pronounced. In addition, internationalization was severely restricted, as students were prevented from crossing borders to study.

A self-powered hybridized sensor inspired by human skin for mimicking fast and slow adaptation

Four types of mechanoreceptors in human skin are capable of sensing different stimuli and transmitting fast adapting (FA) and slow adapting (SA) signals to the brain. To mimic these functions, novel devices have been developed by coupling multiple sensing principles. However, complicated fabrication, high minimum detection limit, and low sensitivity hinder their wide application. In this paper, we report a self-powered mechanical stimulus receptor based on a combination of an artificial ion channel system, a single-electrode triboelectric nanogenerator, and a parallel plate capacitor, which can mimic human skin to monitor both dynamic and static stimuli. The introduction of the capacitive sensing part of this sensor overcomes the problem of conventional potentiometric sensors that are unable to monitor static stimuli due to insufficient electrolyte deformation at low pressure. This device detects external mechanical stimuli with high sensitivity (2.75 kPa−1 under dynamics and 1.18 kPa−1 under statics) and low detection limits (19.5 Pa). For the feasibility study, the signal simulation of Morse code is successfully implemented. In addition, the sensor has been shown to be able to detect human joint activity. This new sensor provides more options for future wearable electronic devices and human–computer interfaces.

QT interval time lag in response to heart rate changes during stress test for Coronary Artery Disease diagnosis

Background: Slow adaptation of the QT interval to abrupt changes in heart rate (HR) can enhance ventricular heterogeneity and has been suggested as a marker of arrhythmic risk. Most investigations on QT rate adaptation lag have been performed in response to step-like HR changes. However, abrupt HR changes are difficult to induce or observe in ECG recordings under ambulatory conditions. Objective:We aim to evaluate the power of indices related to the QT lag in response to ramp-like HR changes in stress test to assess CAD risk. Methods:We quantified the lag between the actual QT series and the memoryless expected QT series, which was obtained by fitting a hyperbolic regression model to the instantaneous QT and HR measurements in stages where their behavior could be assumed stationary. The proposed methodology was applied to analyze ECG stress tests of a subset of 448 patients presenting different risk levels for Coronary Artery Disease (CAD). The QT lag was estimated separately in the exercise and recovery phases. Results:An increase in the estimated QT lag during exercise (from 25 to 36 s) and a decrease during recovery (from 57 to 39 s) were associated with higher CAD risk. The difference between these lags showed significant capacity for CAD risk stratification. Conclusion:The QT lag in response to HR changes can be quantified from a stress test. QT lag values in response to ramp-like HR changes are in ranges comparable to those quantified from abrupt HR changes and show clinical significance to stratify CAD risk.

Adaptive framing of sustainability in CEO letters

PurposeThis study provides insights into the external powers that can influence business leaders' communication on sustainability. It shows how the socio-political context manifested in national and transnational policies, regulations and other socio-political events can influence the CEO talk about sustainability.Design/methodology/approachThis study adopts an interpretative and qualitative method of analysis using the lenses of the theoretical concepts of framing and legitimacy, analysing CEOs’ letters from 10 multinational industrial companies based in Sweden, over the period of 2008–2019.FindingsThe results show that various discourses of sustainability, emerging from policies and regulatory initiatives, socio-political events and civil society activism, are reflected in the ways CEOs frame sustainability over time. This article reveals that CEOs not only lead the discourse of profitable sustainability, but they also slowly adapt their sustainability talk to other discourses led by the policymakers, regulators and civil society. This pattern of a slow adaptation is especially visible in a period characterised by increased discourses of climate urgency and regulations related to social and environmental sustainability.Research limitations/implicationsThe theoretical frame is built by integrating the concepts of legitimacy and framing. Appreciating dynamic notions of legitimacy and framing, the study suggests a novel view of reporting as a film series, presenting many frames of sustainability over time. It helps the study to conceptualise CEO framing of sustainability as adaptive framing. This study suggests using a dynamic notion of adaptive framing in future longitudinal studies of corporate- and accounting communication.Practical implicationsThe results show that policymakers, regulators and civil society, through their initiatives, influence the CEOs' framing of sustainability. It is thus important for regulators to substantiate sustainability-related discourses and develop conceptual tools and language of social and environmental sustainability that can lead CEO framing more effectively.Originality/valueThe study engages with Goffman's notion of dynamic framing. Dynamic framing suggests a novel view of reporting as a film series, presenting many frames of sustainability over time and conceptualises CEO framing of sustainability as adaptive framing.

Gods of Mount Tai: Familiarity and the Material Culture of North China, 1000–2000 by Susan Naquin (review)

Reviewed by: Gods of Mount Tai: Familiarity and the Material Culture of North China, 1000–2000 by Susan Naquin Vincent Goossaert Susan Naquin, Gods of Mount Tai: Familiarity and the Material Culture of North China, 1000–2000. Leiden: Brill, 2022. xv, 538 pp. US$305 (hb). 978-90-04-51641-0 Mount Tai 泰山 (Taishan) and its gods deserve a monumental study. Naquin's book, in the making for some fifteen years and long awaited by the scholarly community, is as towering, rock-solid, impressive, and memorable as its subject. At a length that most presses would not even want to hear about, printed in a large format with two columns per page, and luxuriously illustrated—138 images in-text, most of them in color, not to mention maps, graphs, and tables—this is nothing short of an amazing book. The writing is as beautiful as the visual object: Naquin's renowned prose—utterly devoid of jargon and fashionable terms, surgically precise, and ever critical of any assumption (whether in the sources, in her own writing, or in our reading)—is at the same time elegant and attempts to tell the story from the perspective of ordinary Chinese. For the book tells a story: that of the Jade Maiden (Yunü 玉女), a broken stone statue found atop Taishan (then barren and devoid of any built structure) during the preparations for the fengshan 封禪 sacrifices performed on the mountain by Song emperor Zhenzong 宋真宗 in 1008. The hazily-defined deity was modestly enshrined there and survived [End Page 162] for a few centuries, honored by occasional visitors. She was adopted by a combination of court members, Daoist clerics, and pilgrims, and started to gain a foothold at the foot of the mountain, and then in villages ever further away. The cult grew steadily from the fifteenth century onwards and soon her temples were found throughout the north China plain. She was then called by a variety of names and titles including Holy mother (Shengmu 聖母), Heavenly immortal (Tianxian 天仙), Master of the Azure Cloud (Bixia yuanjun 碧霞元君), and My Lady (niangniang 娘娘), assigned various stories—daughter of the Great Sovereign of the Eastern Peak 東嶽大帝, female alchemical virtuoso, flying bird-like fairy—and represented in forms varying from the alluring young woman, over stern matron and smiling granny, to an almost androgynous figure of authority. Naquin describes with unflinching attention to detail and context these variations in time, space, and medium. Then, by the mid-Qing, this phase of expansion gives way to consolidation; new temples and images keep appearing, but the goddess is now part of the landscape—both figuratively and literally speaking—and finds herself ever more conflated and even confused within a larger mass of female protective deities, found everywhere but with few individual traits. To tell this story of the slow emergence, spectacular success, and then routinization of the goddess both at her original home, Taishan, and in thousands of villages, neighborhoods, and hills, Naquin uses the framework of material culture and the concept of familiarity. This concept, which would deserve to be more fully developed and explored, is based on the idea that people could accept a new deity—the Taishan goddess—on the condition that she seemed familiar enough and was thus represented in media and in demeanors that made sense to them. From this perspective, religious change, such as the success story of a goddess, is not one of bold innovation but rather slow adaptation to the material conditions that prevail locally and remain very stable over the longue durée. For this reason an important part of the book is devoted to describing the physical architecture of her temples and the materials for her images: stone, wood, clay, bronze, and iron for her statues, and canvas and paper for painting and woodblock printing. For each of these materials, Naquin details with great care their sources and local availability, their cost, the presence of technical skills, and the market. In so doing, she offers a lesson in methodology, never taking anything for granted, and constantly asking fundamental questions—who? where? how much? Measuring surviving images of the goddess, for instance, allows her to argue that bronze was mostly used for small...

The time course of chromatic adaptation in human early visual cortex revealed by SSVEPs.

Previous studies have identified at least two components of chromatic adaptation: a rapid component with a time scale between tens of milliseconds to a few seconds, and a slow component with a half-life of about 10 to 30 seconds. The basis of the rapid adaptation probably lies in receptor adaptation at the retina. The neural substrate for the slow adaptation remains unclear, although previous psychophysical results hint at the early visual cortex. A promising approach to investigate adaptation effects in the visual cortex is to analyze steady-state visual evoked potentials (SSVEPs) elicited by chromatic stimuli, which typically use long durations of stimulation. Here, we re-analyzed the data from two previous pattern-reversal SSVEP studies. In these experiments (N = 49 observers in total), SSVEPs were elicited by counter-phase flickering color- or luminance-defined grating stimuli for 150 seconds in each trial. By analyzing SSVEPs with short time windows, we found that chromatic SSVEP responses decreased with increasing stimulation duration and reached a lower asymptote within a minute of stimulation. The luminance SSVEPs did not show any systematic adaptation. The time course of chromatic SSVEPs can be well described by an exponential decay function with a half-life of about 20 seconds, which is very close to previous psychophysical reports. Despite the difference in stimuli between the current and previous studies, the coherent time course may indicate a more general adaptation mechanism in the early visual cortex. In addition, the current result also provides a guide for future color SSVEP studies in terms of either avoiding or exploiting this adaptation effect.

Elucidation of Response and Electrochemical Mechanisms of Bio-Inspired Rubber Sensors with Supercapacitor Paradigm

The electrochemical paradigm of a supercapacitor (SC) is effective for investigating cutting-edge deformable and haptic materials made of magnetic compound fluid (MCF) rubber in order to advance the production of bio-inspired sensors as artificial haptic sensors mimicking human tissues. In the present study, we measure the cyclic voltammetry (CV) profiles and electric properties with electrochemical impedance spectroscopy (EIS) to morphologically evaluate the intrinsic structure of MCF rubber containing fillers and agents. In addition, the electrochemical mechanisms of molecule and particle behavior are theorized using the SC physical framework. The solid-doped fillers in the MCF rubber characterized the behavior of the electrical double-layer capacitor (EDLC). Meanwhile, the liquid agents showed the characteristics of a pseudocapacitor (PC) due to the redox response among the molecules and particles. The potential responses to extraneous stimuli relevant to the EIS properties, categorized as slow adaption (SA), fast adaption (FA), and other type (OT), were also analyzed in terms of the sensory response of the bio-inspired sensor. The categories were based on how the response was induced from the EIS properties. By controlling the EIS properties with different types of doping agents, sensors with various sensory responses become feasible.

Correlations among Firing Rates of Tactile, Thermal, Gustatory, Olfactory, and Auditory Sensations Mimicked by Artificial Hybrid Fluid (HF) Rubber Mechanoreceptors

In order to advance the development of sensors fabricated with monofunctional sensation systems capable of a versatile response to tactile, thermal, gustatory, olfactory, and auditory sensations, mechanoreceptors fabricated as a single platform with an electric circuit require investigation. In addition, it is essential to resolve the complicated structure of the sensor. In order to realize the single platform, our proposed hybrid fluid (HF) rubber mechanoreceptors of free nerve endings, Merkel cells, Krause end bulbs, Meissner corpuscles, Ruffini endings, and Pacinian corpuscles mimicking the bio-inspired five senses are useful enough to facilitate the fabrication process for the resolution of the complicated structure. This study used electrochemical impedance spectroscopy (EIS) to elucidate the intrinsic structure of the single platform and the physical mechanisms of the firing rate such as slow adaption (SA) and fast adaption (FA), which were induced from the structure and involved the capacitance, inductance, reactance, etc. of the HF rubber mechanoreceptors. In addition, the relations among the firing rates of the various sensations were clarified. The adaption of the firing rate in the thermal sensation is the opposite of that in the tactile sensation. The firing rates in the gustation, olfaction, and auditory sensations at frequencies of less than 1 kHz have the same adaption as in the tactile sensation. The present findings are useful not only in the field of neurophysiology, to research the biochemical reactions of neurons and brain perceptions of stimuli, but also in the field of sensors, to advance salient developments in sensors mimicking bio-inspired sensations.

A comparative analysis review of digital transformation stage in developing countries

Purpose: Digital Transformation (DX) is a phenomenon that must be addressed properly so that its benefits can be optimized. Slow adaptation to DT leads to the destruction of the industry and threatens its sustainability. This article reveals significant insights in describing the trend of DX stages, especially in developing countries.Design/methodology/approach: Based on a comparative analysis of research related to DX in developing countries in reputable journals, more than 900 articles that reviewed DX. By conducting a strict and thorough screening of DX stages in developing countries, especially on the topic of Information Systems, 60 relevant articles were obtained.Findings: DX barriers in phase 1 comprise the fact that access and infrastructure are starting to be bridged, but not completely. DX barriers in developed countries have shifted predominantly from stage 1 to stage 2. More than 80 of the revealed indicators contribute to the success of DX in developing countries. In addition, this article also discusses various future research opportunities and essential indicators that intersect in stages 1, 2, and 3.Originality/value: DX barriers in developed countries have shifted predominantly from stage 1 to stage 2. More than 80 of the revealed indicators contribute to the success of DX in developing countries.

Population spiking and bursting in next-generation neural masses with spike-frequency adaptation.

Spike-frequency adaptation (SFA) is a fundamental neuronal mechanism taking into account the fatigue due to spike emissions and the consequent reduction of the firing activity. We have studied the effect of this adaptation mechanism on the macroscopic dynamics of excitatory and inhibitory networks of quadratic integrate-and-fire (QIF) neurons coupled via exponentially decaying post-synaptic potentials. In particular, we have studied the population activities by employing an exact mean-field reduction, which gives rise to next-generation neural mass models. This low-dimensional reduction allows for the derivation of bifurcation diagrams and the identification of the possible macroscopic regimes emerging both in a single and in two identically coupled neural masses. In single populations SFA favors the emergence of population bursts in excitatory networks, while it hinders tonic population spiking for inhibitory ones. The symmetric coupling of two neural masses, in absence of adaptation, leads to the emergence of macroscopic solutions with broken symmetry, namely, chimera-like solutions in the inhibitory case and antiphase population spikes in the excitatory one. The addition of SFA leads to new collective dynamical regimes exhibiting cross-frequency coupling (CFC) among the fast synaptic timescale and the slow adaptation one, ranging from antiphase slow-fast nested oscillations to symmetric and asymmetric bursting phenomena. The analysis of these CFC rhythms in the θ-γ range has revealed that a reduction of SFA leads to an increase of the θ frequency joined to a decrease of the γ one. This is analogous to what has been reported experimentally for the hippocampus and the olfactory cortex of rodents under cholinergic modulation, which is known to reduce SFA.

Temporal profiles of neuronal responses to repeated tone stimuli in the mouse primary auditory cortex

How the auditory system processes temporal information of sound has been investigated extensively using repeated stimuli. Recent studies on how the response of neurons in the primary auditory cortex (A1) changes with the progression of stimulus repetition, have reported response temporal profiles of two categories: “adaptation”, i.e., gradual decrease, and “facilitation”, i.e., gradual increase. To explore the existence of profiles of other categories and to examine the tone-frequency-dependence of the profile category in single neurons, here we studied the response of mouse A1 neurons to four or five tone-trains; each train comprised 10 identical tone pips, with 0.5-s inter-tone-intervals, and the four or five trains differed only in tone frequency. The response to each tone in a train was evaluated using the peak of the ON response, and how the peak response changed with the tone number in the train, i.e., the response temporal profile, was examined. We confirmed the existence of profiles of both “adaptation” and “facilitation” categories; “adaptation” could be further subcategorized into “slow adaptation” and “fast adaptation” profiles, with the latter being encountered more frequently. Moreover, two new categories of non-monotonic profiles were identified: an “adaptation with recovery” profile and a “facilitation followed by adaptation” profile. Examination of single neurons with trains of different tone frequencies revealed that some A1 neurons exhibited profiles of the same category to tone trains of different tone frequencies, whereas others exhibited profiles of different categories, depending on the tone frequency. These results demonstrate the variety in the response temporal profiles of mouse A1 neurons, which may benefit the encoding of individual tones in a train.

Estimation of Fast and Slow Adaptions in the Tactile Sensation of Mechanoreceptors Mimicked by Hybrid Fluid (HF) Rubber with Equivalent Electric Circuits and Properties.

In order to advance engineering applications of robotics such as wearable health-monitoring devices, humanoid robots, etc., it is essential to investigate the tactile sensations of artificial haptic sensors mimicking bioinspired human cutaneous mechanoreceptors such as free nerve endings, Merkel's cells, Krause end bulbs, Meissner corpuscles, Ruffini endings, and Pacinian corpuscles. The generated receptor's potential response to extraneous stimuli, categorized as slow adaption (SA) or fast adaption (FA), is particularly significant as a typical property. The present study addressed the estimation of SA and FA by utilizing morphologically fabricated mechanoreceptors made of our proposed magnetically responsive intelligent fluid, hybrid fluid (HF), and by applying our proposed electrolytic polymerization. Electric circuit models of the mechanoreceptors were generated using experimental data on capacitance and inductance on the basis of the electric characteristics of impedance. The present results regarding equivalent firing rates based on FA and SA are consistent with the FA and SA findings of vital mechanoreceptors by biomedical analysis. The present investigative process is useful to clarify the time of response to a force on the fabricated artificial mechanoreceptor.

Spontaneous Activity of the Local GABAergic Synaptic Network Causes Irregular Neuronal Firing in the External Globus Pallidus.

Autonomously firing GABAergic neurons in the external globus pallidus (GPe) form a local synaptic network. In slices, most GPe neurons receive a continuous inhibitory synaptic barrage from 1 or 2 presynaptic GPe neurons. We measured the barrage's effect on the firing rate and regularity of GPe neurons in male and female mice using perforated patch recordings. Silencing the firing of parvalbumin-positive (PV+) GPe neurons by activating genetically expressed Archaerhodopsin current increased the firing rate and regularity of PV- neurons. In contrast, silencing Npas1+ GPe neurons with Archaerhodopsin had insignificant effects on Npas1- neuron firing. Blocking spontaneous GABAergic synaptic input with gabazine reproduced the effects of silencing PV+ neuron firing on the firing rate and regularity of Npas1+ neurons and had similar effects on PV+ neuron firing. To simulate the barrage, we constructed conductance waveforms for dynamic clamp based on experimentally measured inhibitory postsynaptic conductance trains from 1 or 2 unitary local connections. The resulting inhibition replicated the effect on firing seen in the intact active network in the slice. We then increased the number of unitary inputs to match estimates of local network connectivity in vivo As few as 5 unitary inputs produced large increases in firing irregularity. The firing rate was also reduced initially, but PV+ neurons exhibited a slow spike-frequency adaptation that partially restored the rate despite sustained inhibition. We conclude that the irregular firing pattern of GPe neurons in vivo is largely due to the ongoing local inhibitory synaptic barrage produced by the spontaneous firing of other GPe neurons.SIGNIFICANCE STATEMENT Functional roles of local axon collaterals in the external globus pallidus (GPe) have remained elusive because of difficulty in isolating local inhibition from other GABAergic inputs in vivo, and in preserving the autonomous firing of GPe neurons and detecting their spontaneous local inputs in slices. We used perforated patch recordings to detect spontaneous local inputs during rhythmic firing. We found that the autonomous firing of single presynaptic GPe neurons produces inhibitory synaptic barrages that significantly alter the firing regularity of other GPe neurons. Our findings suggest that, although GPe neurons receive input from only a few other GPe neurons, each local connection has a large impact on their firing.