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• We assessed posture-dependent changes in cortical motor maps in awake marmosets. • The results demonstrated rapid modulation in forelimb motor maps. • Hindlimb posture was particularly effective in inducing these modulations. • Posture is a crucial variable to be controlled in future studies of motor control. Recent neuroimaging and electrophysiological studies have suggested substantial short-term plasticity in the topographic maps of the primary motor cortex (M1). However, previous methods lack the temporal resolution to detect rapid modulation of these maps, particularly in naturalistic conditions. To address this limitation, we previously developed a rapid stimulation mapping procedure with implanted cortical surface electrodes. In this study, employing our previously established procedure, we examined rapid topographical changes in forelimb M1 motor maps in three awake male marmoset monkeys. The results revealed that although the hotspot (the location in M1 that elicited a forelimb muscle twitch with the lowest stimulus intensity) remained constant across postures, the stimulus intensity required to elicit the forelimb muscle twitch in the perihotspot region and the size of motor representations were posture-dependent. Hindlimb posture was particularly effective in inducing these modulations. The angle of the body axis relative to the gravitational vertical line did not alter the motor maps. These results provide a proof of concept that a rapid stimulation mapping system with chronically implanted cortical electrodes can capture the dynamic regulation of forelimb motor maps in natural conditions. Moreover, they suggest that posture is a crucial variable to be controlled in future studies of motor control and cortical plasticity. Further exploration is warranted into the neural mechanisms regulating forelimb muscle representations in M1 by the hindlimb sensorimotor state. [ABSTRACT FROM AUTHOR]

Activity and physical effort positively affect a person's psychophysical state and emotional experience. Interest in the phenomenon of flow, the state of perceived arousal, stems from its relationship to an individual's intrinsic motivation. Flow is an area of research in many fields, including sports. Nowadays, solutions are being sought to support the traditional assessment of cognitive and affective states using analysis of physiological signals. Therefore, the present study analysed and estimated the physiological responses that may occur during the induction of a flow state between exercises stimulated by additional metrorhythmic stimuli. Thirty-six healthy subjects participated in the study. The effects of various metrorhythmic stimuli on the body's physiological response during the subjects' free gait were examined. The physiological response and flow intensity were evaluated when the rate of individual stimuli was changed, and the rate was enforced. Several statistically significant variables and correlations were determined for physiological indicators depending on the stage of the study conducted and the level of flow experienced. A positive, statistically significant correlation of flow and HRV frequency variables was obtained. The results also confirm previous literature reports on the relationship between flow response and frequency heart rate variability during physical activity. [ABSTRACT FROM AUTHOR]

Pain perception is influenced not only by sensory input from afferent neurons but also by cognitive factors such as prior expectations. It has been suggested that overly precise priors may be a key contributing factor to chronic pain states such as neuropathic pain. However, it remains an open question how overly precise priors in favor of pain might arise. Here, we first verify that a Bayesian approach can describe how statistical integration of prior expectations and sensory input results in pain phenomena such as placebo hypoalgesia, nocebo hyperalgesia, chronic pain, and spontaneous neuropathic pain. Our results indicate that the value of the prior, which is determined by the internal model parameters, may be a key contributor to these phenomena. Next, we apply a hierarchical Bayesian approach to update the parameters of the internal model based on the difference between the predicted and the perceived pain, to reflect that people integrate prior experiences in their future expectations. In contrast with simpler approaches, this hierarchical model structure is able to show for placebo hypoalgesia and nocebo hyperalgesia how these phenomena can arise from prior experiences in the form of a classical conditioning procedure. We also demonstrate the phenomenon of offset analgesia, in which a disproportionally large pain decrease is obtained following a minor reduction in noxious stimulus intensity. Finally, we turn to simulations of neuropathic pain, where our hierarchical model corroborates that persistent non-neuropathic pain is a risk factor for developing neuropathic pain following denervation, and additionally offers an interesting prediction that complete absence of informative painful experiences could be a similar risk factor. Taken together, these results provide insight to how prior experiences may contribute to pain perception, in both experimental and neuropathic pain, which in turn might be informative for improving strategies of pain prevention and relief. Author summary: To efficiently navigate the world and avoid harmful situations, it is beneficial to learn from prior pain experiences. This learning process typically results in certain contexts being associated with an expected level of pain, which subsequently influences pain perception. While this process of pain anticipation has evolved as a mechanism for avoiding harm, recent research indicates overly precise expectations of pain may in fact contribute to certain chronic pain conditions, in which pain persists even after tissue damage has healed, or even arises without any initiating injury. However, it remains an open question how prior experiences contribute to such overly precise expectations of pain. Here, we mathematically model the pain-learning-process. Our model successfully describes several counterintuitive but well-documented pain phenomena. We also make predictions of how prior experiences may contribute the perception of pain and how the same learning process could be leveraged to improve strategies of pain prevention and relief. [ABSTRACT FROM AUTHOR]

The spatial organization of inositol 1,4,5-trisphosphate (IP 3)-evoked Ca2+ signals underlies their versatility. Low stimulus intensities evoke Ca2+ puffs, localized Ca2+ signals arising from a few IP 3 receptors (IP 3 Rs) within a cluster tethered beneath the plasma membrane. More intense stimulation evokes global Ca2+ signals. Ca2+ signals propagate regeneratively as the Ca2+ released stimulates more IP 3 Rs. How is this potentially explosive mechanism constrained to allow local Ca2+ signaling? We developed methods that allow IP 3 produced after G-protein coupled receptor (GPCR) activation to be intercepted and replaced by flash photolysis of a caged analog of IP 3. We find that phosphatidylinositol 4,5-bisphosphate (PIP 2) primes IP 3 Rs to respond by partially occupying their IP 3 -binding sites. As GPCRs stimulate IP 3 formation, they also deplete PIP 2 , relieving the priming stimulus. Loss of PIP 2 resets IP 3 R sensitivity and delays the transition from local to global Ca2+ signals. Dual regulation of IP 3 Rs by PIP 2 and IP 3 through GPCRs controls the transition from local to global Ca2+ signals. [Display omitted] • PIP 2 binding to the IP 3 -binding site of IP 3 receptors primes them to respond to IP 3 • Endogenous receptors reduce the sensitivity of IP 3 receptors by degrading PIP 2 • Receptor regulation of PIP 2 controls the switch from local to global Ca2+ signals Ivanova et al. show that binding of PIP 2 to IP 3 receptors primes them to respond to IP 3. PIP 2 depletion reduces the frequency of Ca2+ puffs and delays global Ca2+ signals. Dynamic regulation of PIP 2 levels by endogenous signaling pathways controls the transition from local to global Ca2+ signals. [ABSTRACT FROM AUTHOR]

Key points Transcutaneous electrical stimulation with repetitive bursts of a kilohertz carrier frequency is thought to be less painful than conventional pulsed currents by reducing the sensitivity of pain receptors. However, no purported benefit has been shown unequivocally. We compared the effects of carrier‐frequency stimulation and conventional stimulation on pain tolerance and the thresholds for sensory and motor axons in twelve participants. The ulnar nerve was stimulated transcutaneously with a conventional single pulse and 5 and 10 kHz carrier‐frequency waveforms that had 5 and 10 pulses, respectively, when delivered in bursts of ∼1 ms duration. Phase durations were adjusted across waveform types to match the total charge for a given current amplitude. Single bursts of stimulation were delivered from 1 mA up until no longer tolerable. This was repeated with repetitive bursts of stimulation at 20 Hz for 1 s. Participants tolerated higher current amplitudes with both carrier‐frequency waveforms than conventional stimulation, with repetitive bursts more painful than single bursts. However, compared to conventional stimulation, carrier‐frequency waveforms required more current to produce sensory and motor‐threshold responses and to obtain a maximal motor response (Mmax). When the current at pain tolerance was normalised to the current at Mmax, participants tolerated lower stimulus intensities with carrier‐frequency waveforms than conventional stimulation. These findings indicate that there is little to no benefit in using carrier‐frequency waveforms to minimise the discomfort from electrical stimulation as the increase in stimulus intensity at pain tolerance is more than offset by reduced effectiveness in the activation of sensory and motor axons. Transcutaneous electrical stimulation with repetitive bursts of a kilohertz carrier‐frequency waveform is thought to be less painful than conventional pulsed currents. For ulnar nerve stimulation, when stimulus waveforms were matched for total phase charge, participants tolerated higher current amplitudes with carrier‐frequency stimulation than conventional stimulation. However, compared to conventional stimulation, carrier‐frequency waveforms required more current to produce a threshold response in both sensory and motor axons and to produce a maximal motor response (Mmax). When current at pain tolerance was normalised to current at Mmax, participants tolerated lower stimulus intensities with carrier‐frequency waveforms than conventional stimulation. Carrier‐frequency waveforms provide little to no benefit in minimising the discomfort from transcutaneous electrical stimulation as the increase in stimulus intensity at pain tolerance is more than offset by reduced effectiveness in activating sensory and motor axons. [ABSTRACT FROM AUTHOR]

In this article, we proposed the use of optically pumped spin vertical-cavity surface-emitting laser (Spin-VCSEL) to create a photonic spiking neuron. We studied the dynamics of excitability and inhibitability under optical injection and analyzed the propagation characteristics of spiking information between unidirectionally-coupled Spin-VCSEL neurons. Our results demonstrated that by properly selecting parameters such as negative disturbance intensity from stimulus, pump ellipticity, and frequency detuning, Spin-VCSEL can achieve repeatable spiking output mode. Additionally, under certain conditions, it is possible to achieve inhibitory spiking output by selecting positive disturbance intensity from stimulus. By adjusting the duration and intensity of the disturbance, we can obtain controllable spiking responses for both excitable and inhibitory neurons. Furthermore, we found that under optimized injection strength, the spiking signal from the transmitter of Spin-VCSEL can be successfully propagated to the cascaded receiver with high quality. This work is meaningful because Spin-VCSEL offers new control dimensions such as pump ellipticity. Therefore, our study provides a valuable new choice for neuron construction of photonic spiking neural networks (PSNN). [ABSTRACT FROM AUTHOR]

Introduction: A full understanding of the integration of the mechanisms of vascular tone regulation requires an interrogation of the temporal behavior of arterioles across vasoactive challenges. Building on previous work, the purpose of the present study was to start to interrogate the temporal nature of arteriolar tone regulation with physiological stimuli. Methods: We determined the response rate of ex vivo proximal and in situ distal resistance arterioles when challenged by one-, two-, and three-parameter combinations of five major physiological stimuli (norepinephrine, intravascular pressure, oxygen, adenosine [metabolism], and intralumenal flow). Predictive machine learning models determined which factors were most influential in controlling the rate of arteriolar responses. Results: Results indicate that vascular response rate is dependent on the intensity of the stimulus used and can be severely hindered by altered environments, caused by application of secondary or tertiary stimuli. Advanced analytics suggest that adrenergic influences were dominant in predicting proximal arteriolar response rate compared to metabolic influences in distal arterioles. Conclusion: These data suggest that the vascular response rate to physiologic stimuli can be strongly influenced by the local environment. Translating how these effects impact vascular networks is imperative for understanding how the microcirculation appropriately perfuses tissue across conditions. [ABSTRACT FROM AUTHOR]

Motion vision is vital for a wide range of animal behaviors. Fiddler crabs, for example, rely heavily on motion to detect the movement of avian predators. They are known to detect first-order motion using both intensity (defined by spatiotemporal correlations in luminance) and polarization information (defined separately as spatiotemporal correlations in the degree and/or angle of polarization). However, little is known about their ability to detect second-order motion, another important form of motion information; defined separately by spatiotemporal correlations in higher-order image properties. In this work we used behavioral experiments to test how fiddler crabs (Afruca tangeri) responded to both second-order intensity and polarization stimuli. Fiddler crabs responded to a number of different intensity based second-order stimuli. Furthermore, the crabs also responded to second-order polarization stimuli, a behaviorally relevant stimulus applicable to an unpolarized flying bird when viewed against a polarized sky. The detection of second-order motion in polarization is, to the best of our knowledge, the first demonstration of this ability in any animal. This discovery therefore opens a new dimension in our understanding of how animals use polarization vision for target detection and the broader importance of second-order motion detection for animal behavior. Fiddler crabs detect second-order motion in both intensity and polarization, a finding that expands our understanding of motion vision in animals and its role in predator detection and behavior. [ABSTRACT FROM AUTHOR]

Multimodal integration is a core neural process with a keen relevance during ecological tasks requiring learning and memory, such as foraging. The benefits of learning multimodal signals imply solving whether the components come from a single event. This challenge presumably depends on the timing and intensity of the stimuli. Here, we used simultaneous and alternate presentations of olfactory and visual stimuli, at low and high intensities, to understand how temporal and intensity variations affect the learning of a bimodal stimulus and its components. We relied on the conditioning of the proboscis extension response (PER) to train honey bees to an appetitive learning task with bimodal stimuli precisely controlled. We trained bees to stimuli with different synchronicity and intensity levels. We found that synchronicity, order of presentation, and intensity significantly impacted the probability of exhibiting conditioned PER responses and the latency of the conditioned responses. At low intensities, synchronous bimodal inputs produced maximal multisensory enhancement, while asynchronous temporal orders led to lower performances. At high intensities, the relative advantage of the synchronous stimulation diminished, and asynchronous stimuli produced similar performances. Memory retention was higher for the olfactory component and bimodal stimuli compared to the visual component, irrespective of the training's temporal configuration. Bees retained the asynchronous bimodal configuration to a lesser extent than the synchronous one, depending on the stimulus intensity. We conclude that time (synchrony), order of presentation, and intensity have interdependent effects on bee learning and memory performance. This suggests caution when assessing the independent effects of each factor. [ABSTRACT FROM AUTHOR]

This study examined the relationship between the intensity of emotional expressions in facial stimuli and receivers' decoding accuracy for six basic emotions: anger, disgust, fear, happiness, sadness, and surprise. A laboratory experiment was conducted using the forced‐choice method, in which the intensity of each stimulus was manipulated at every 10% interval using the morphing technique. To explore whether a linear relationship would be observed when the intensity was finely manipulated at 10% intervals, a hierarchical multiple regression analysis was performed. The mean percentage of correct responses for each stimulus was the dependent variable, and the linear, quadratic, and cubic terms of the stimulus intensity were the independent variables. The results showed that the linear model was not adopted as the final model for all facial expressions; that is, the effect of the squared term of intensity was significant for anger, disgust, fear, and sadness, while the effect of the cubic term of intensity was significant for happiness and surprise. Our findings indicate that a higher intensity of emotional expression does not yield higher decoding accuracy. [ABSTRACT FROM AUTHOR]

Self‐classification technology has remarkable potential for autonomously discerning various stimuli without any circuit or software assistance, enabling it to realize electronic skin. In conventional self‐classification systems that rely on complex circuitry for operation, integrating the sensing and algorithm processing units inevitably leads to bulkiness in devices and bottlenecks in signal processing. In this study, the novel double‐sided structure inspired by the human nervous system is newly designed for a self‐classifying sensor (SCS) without the need for additional circuits. The sensor is layered with Ag nanocomposites that have been mechanically enhanced via interface engineering and surface treatment techniques. This structure enables the resistance‐capacitance hybrid operation, facilitating the detection and distinguishment of changes in strain, pressure, and temperature within a single device, which mimics the human sensing recognition process. Moreover, the intensity of the applied stimuli is determined by analyzing the detected signal, and precise localization of the stimuli is achieved by arraying the sensors. With its self‐classification capabilities, SCS opens promising avenues for applications in soft robotics and advanced multifunctional sensor platforms, providing a sensing system characterized by simplicity and efficiency. [ABSTRACT FROM AUTHOR]

• Methods for conducting pudendal SEPs vary, and most publications do not report enough detail to replicate their protocol. • Most pudendal SEP research has been conducted in males, highlighting the paucity of pelvic neurophysiology research in females. • There is a need to develop optimal sex- and patient-specific methods to investigate all branches of the pudendal nerve. The purpose of this systematic review was to characterize methodologies reported in the literature to elicit and record pudendal somatosensory evoked potentials (SEPs) in human adults. We conducted an electronic literature search in MEDLINE, Embase, CENTRAL, and CINAHL for studies that elicited pudendal SEPs via electrical stimulation and recorded responses though electroencephalography. From included studies, we extracted methodological details of how the SEPs were evoked and recorded. 132 studies were included in our review. The majority of participants were male (n = 6742/8526, 79%). Almost all studies stimulated the dorsal nerve of penis/clitoris. Stimulus parameters varied, with most standardizing stimulus intensity to 2-4x perceptual threshold, pulse duration to 0.1–0.2 ms, and frequency to 3 Hz. The number of stimuli recorded varied by clinical population. Our results demonstrate the inconsistencies of pudendal SEP methodology in the literature, with the majority (77%) of publications not reporting enough detail to reasonably replicate their protocol. Most research to date has been conducted in males, highlighting the paucity of female pelvic neurophysiology research. We propose a Pudendal SEP Reporting Checklist for adequate reporting of pudendal SEP protocols. Optimal sex- and patient-specific methodologies to investigate all branches of the pudendal nerve need to be established. [ABSTRACT FROM AUTHOR]

The sensory–neuromorphic interface is key to the application of neuromorphic electronics. Artificial spiking neurons and artificial sensory nerves have been created, and a few studies showed a complete neuromorphic system through cointegration with synaptic electronics. However, artificial synaptic devices and systems often do not work in real environments, which limits their ability to provide realistic neural simulations and interface with biological nerves. We report a sensory–neuromorphic interface that uses a fiber synapse to emulate a biological afferent nerve. For the first time, a sensing–neuromorphic interface is connected to a living organism for peripheral nerve stimulation, allowing the organism to establish a connection with its surrounding environment. The interface converts perceived environmental information into analog electrical signals and then into frequency‐dependent pulse signals, which simplify the information interface between the sensor and the pulse‐data processing center. The frequency of the interface shows a sublinear dependence on strain amplitude at different stimulus intensities, and can deliver increased frequency spikes at potentially damaging stimulus intensities, similar to the response of biological afferent nerves. To verify the application of this interface, a system that monitors strain and provides an overstrain alarm was constructed based on this afferent neural circuit. The system has a response time of <2 ms, which is compatible with the response time in biological systems. The interface can be potentially extended to process signals from almost any type of sensors for other afferent senses, and these results demonstrate the potential for neuromorphic interfaces to be applied to bionic sensory interfaces. [ABSTRACT FROM AUTHOR]

Purpose Methods Results Conclusion Level of Evidence The primary purpose of this randomized, cross‐sectional study was to determine whether operant conditioning of motor evoked torque (MEPTORQUE) in individuals with total knee arthroplasty (TKA) increases quadriceps MEPTORQUE responses within a single session and induces acute corticospinal adaptations by producing sustained increases in MEPTORQUE after training. A secondary purpose was to determine if these changes were affected by the stimulus intensity and number of training trials.Thirty participants were block‐randomized into one of three groups based on the participant's active motor threshold (100%, 120%, and 140%) to evaluate the effect of stimulus intensity. Participants received three blocks of conditioning trials (COND), where they trained to increase their MEPTORQUE. Control (CTRL) transcranial magnetic stimulation pulses were provided before and after each COND block to establish baseline corticospinal excitability and to evaluate the effect of the number of training trials. Two MEPTORQUE recruitment curves were collected to evaluate the effect of up‐conditioning on acute corticospinal adaptations.TKA participants were able to successfully increase their MEPTORQUE in a single session (F3,81 = 10.719, p < 0.001) and induce acute corticospinal adaptations (F1,27 = 20.029, p < 0.001), indicating sustained increases in quadriceps corticospinal excitability due to operant conditioning. While the stimulus intensity used during training did not affect the ability to increase MEPTORQUE (F2,26 = 0.021, n.s.) or its associated acute adaptations (F2,27 = 0.935, n.s.), the number of training trials significantly influenced these outcomes (F3,81 = 10.719, p < 0.001; F3,81 = 4.379, p = 0.007, respectively).Operant conditioning is a feasible approach for improving quadriceps corticospinal excitability following TKA. While any of the three stimulus intensities evaluated in this study may be used in future operant conditioning interventions, using a low or moderate stimulus intensity and 150 training trials are recommended to improve treatment efficiency and patient adherence.Level II. [ABSTRACT FROM AUTHOR]

Prepulse inhibition of perceived stimulus intensity (PPIPSI) is a phenomenon where a weak stimulus preceding a stronger one reduces the perceived intensity of the latter. Previous studies have shown that PPIPSI relies on attention and is sensitive to stimulus onset asynchrony (SOA). Longer SOAs may increase conscious awareness of the impact of gating mechanisms on perception by allowing more time for attention to be directed toward relevant processing channels. In other psychophysiological paradigms, temporal predictability improves attention to task relevant stimuli and processes. We hypothesized that temporal predictability may similarly facilitate attention being directed toward the pulse and its processing in PPIPSI. To examine this, we conducted a 2 (SOA: 90 ms, 150 ms) × 2 (predictability: low, high) experiment, where participants were tasked with comparing the perceived intensity of an acoustic pulse‐alone against one preceded by a prepulse. The relationship between PPIPSI and cortical PPI (N1‐P2 inhibition) was also investigated. Significant main effects of temporal predictability, SOA, and cortical PPI were revealed. Under high temporal predictability, both SOAs (90 and 150 ms) elicited greater PPIPSI. The findings indicate that temporal predictability enhances the timely allocation of finite attentional resources, increasing PPIPSI observations by facilitating perceptual access to the gated pulse signal. Moreover, the finding that reductions in N1‐P2 magnitude by a prepulse are associated with increased probability of the participants perceiving the pulse “with prepulse” as less intense, suggests that under various experimental conditions, the link between these cortical processes and perception is similarly engaged. [ABSTRACT FROM AUTHOR]

Understanding sensory processing relies on the establishment of a consistent relationship between the stimulus space, its neural representation, and perceptual quality. In olfaction, the difficulty in establishing these links lies partly in the complexity of the underlying odor input space and perceptual responses. Based on the recently proposed primacy model for concentration invariant odor identity representation and a few assumptions, we have developed a theoretical framework for mapping the odor input space to the response properties of olfactory receptors. We analyze a geometrical structure containing odor representations in a multidimensional space of receptor affinities and describe its low-dimensional implementation, the primacy hull. We propose the implications of the primacy hull for the structure of feedforward connectivity in early olfactory networks. We test the predictions of our theory by comparing the existing receptor-ligand affinity and connectivity data obtained in the fruit fly olfactory system. We find that the Kenyon cells of the insect mushroom body integrate inputs from the high-affinity (primacy) sets of olfactory receptors in agreement with the primacy theory. Author summary: Sensory systems face the problem of computing stimulus identity that is invariant with respect to multiple stimulus features. In the olfactory system, odorant percepts often retain their identity despite substantial variations in the odorant concentration. How can olfactory networks robustly represent odorant identity despite variable stimulus intensity? In the nose, odorants are sensed by the odorant receptors (ORs), the specialized proteins that can be activated by the odorant molecules. In this study, we develop a theory for encoding concentration-invariant odor objects. We propose that the identities of a small group of the most sensitive ORs represent odorant identity in a concentration-invariant manner. We argue that, although absolute values of olfactory receptor responses may depend on concentration, their ranking remains invariant, leading to invariance in the membership of the most sensitive (primary) group. We call this form of representation of concentration invariant odorant identity the primacy coding model. We investigate the mathematical principles underlying the primacy coding model and test its predictions using connectivity and neuronal activations data from the fruit fly olfactory system. We find that neurons in the fly olfactory system integrate inputs from the high-affinity (primacy) sets of ORs in agreement with the primacy theory. [ABSTRACT FROM AUTHOR]

Several gaps persist in haptic device development due to the multifaceted nature of the sense of touch. Existing gaps include challenges enhancing touch feedback fidelity, providing diverse haptic sensations, and ensuring wearability for delivering tactile stimuli to the fingertips. Here, we introduce the Bioinspired Adaptable Multiplanar Haptic system, offering mechanotactile/steady and vibrotactile pulse stimuli with adjustable intensity (up to 298.1 mN) and frequencies (up to 130 Hz). This system can deliver simultaneous stimuli across multiple fingertip areas. The paper includes a full characterisation of our system. As the device can play an important role in further understanding human touch, we performed human stimuli sensitivity and differentiation experiments to evaluate the capability of delivering mechano-vibrotactile, variable intensity, simultaneous, multiplanar and operator agnostic stimuli. Our system promises to accelerate the development of touch perception devices, providing painless, operator-independent data crucial for researching and diagnosing touch-related disorders. Challenges persist in haptic device development due to the complex nature of touch. The authors propose a Bioinspired Adaptable Multiplanar Haptic system providing multipoint and variable intensity pulse stimuli (0-130 Hz) across multiple fingertip areas, enabling deeper study of touch skin sensors. [ABSTRACT FROM AUTHOR]

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This paper presents an original method for noninvasive recording of electroretinogram from both compound eyes of insects. The method was found to be highly reliable and reproducible. The photovoltaic effect, which distorts response amplitude and shape, was eliminated by using a gold recording electrode. The data obtained using this method showed that the magnitudes of the responses of the eyes in pearl mutant cockroaches, which lack screening pigment, to light stimuli were approximately four times greater than those of wild-type insects. The time to peak response decreased with increases in stimulus light intensity for shortwave and long-wave stimuli. Pearl cockroaches reached maximum responses faster than wild-type cockroaches. Results of covariance analysis indicated that these differences could not be explained completely in terms of an increase in the number of photons reaching photoreceptor membranes. This suggests that there are additional differences in the physiology of the compound eye between mutant and wild-type individuals. The positive deflection of the potential after the end of light stimulation depended on light intensity and was a reflection of receptor cell hyperpolarization. [ABSTRACT FROM AUTHOR]

Pain is a complex emotional experience that still remains challenging to manage. Previous functional magnetic resonance imaging (fMRI) studies have associated pain with distributed patterns of brain activity (i.e. brain decoders), but it is still unclear whether these observations reflect causal mechanisms. To address this question, we devised a new neurofeedback approach using real-time decoding of fMRI data to test if modulating pain-related multivoxel fMRI patterns could lead to changes in subjective pain experience. We first showed that subjective pain ratings can indeed be accurately predicted using a real-time decoding approach based on the stimulus intensity independent pain signature (SIIPS) and the neurologic pain signature (NPS). Next, we trained participants (n = 16) in a double-blinded decoded fMRI neurofeedback experiment to up- or downregulate the SIIPS. Our results indicate that participants can learn to downregulate the expression of SIIPS independently from NPS expression. Importantly, the success of this neurofeedback training was associated with the perceived intensity of painful stimulation following the intervention. Taken together, these results indicate that closed-loop brain imaging can be efficiently conducted using a priori fMRI decoders of pain, potentially opening up a new range of applications for decoded neurofeedback, both for clinical and basic science purposes. This article is part of the theme issue 'Neurofeedback: new territories and neurocognitive mechanisms of endogenous neuromodulation'. [ABSTRACT FROM AUTHOR]

Background: Previous studies have found that inhibitory priming with continuous theta burst stimulation (cTBS) can enhance the effect of subsequent excitatory conditioning stimuli with intermittent theta burst stimulation (iTBS) in the upper limbs. However, whether this combined stimulation approach elicits a comparable compensatory response in the lower extremities remains unclear. This study aimed to investigate how cTBS preconditioning modulated the effect of iTBS on motor cortex excitability related to the lower limb in healthy individuals. Methods: Using a randomised cross-over design, a total of 25 healthy participants (19 females, mean age = 24.80 yr) were recruited to undergo three different TBS protocols (cTBS + iTBS, sham cTBS + iTBS, sham cTBS + sham iTBS) in a random order. Each TBS intervention was administered with one-week intervals. cTBS and iTBS were administered at an intensity of 80% active motor threshold (AMT) delivering a total of 600 pulses. Before intervention (T0), immediately following intervention (T1), and 20 min after intervention (T2), the corticomotor excitability was measured for the tibialis anterior muscle of participants' non-dominant leg using a Magneuro100 stimulator and matched double-cone coil. The average amplitude of the motor-evoked potential (MEP) induced by applying 20 consecutive monopulse stimuli at an intensity of 130% resting motor threshold (RMT) was collected and analysed. Results: Compare with T0 time, the MEP amplitude (raw and normalised) at T1 and T2 showed a statistically significant increase following the cTBS + iTBS protocol (p < 0.01), but no significant differences were observed in amplitude changes following other protocols (sham cTBS + iTBS and sham cTBS + sham iTBS) (p > 0.05). Furthermore, no statistically significant difference was found among the three protocols at any given time point (p > 0.05). Conclusions: Preconditioning the lower extremity motor cortex with cTBS prior to iTBS intervention can promptly enhance its excitability in healthy participants. This effect persists for a minimum duration of 20 min. [ABSTRACT FROM AUTHOR]

Ionomeric polymer‐metal composites (IPMC) are advanced materials designed to mimic biological systems. Their performance depends on various factors, including electrical stimulus intensity, membrane hydration, ionic migration, and Young's modulus. However, there is a lack of studies in the literature investigating how the water absorption capacity and elastic modulus change over time in IPMCs. Understanding the hydration level variation as a function of time is essential because as this parameter deviates, the ionic migration capacity and Young's modulus also change, altering the device's electromechanical efficiency over time. To address this research gap, Nafion/Pt‐based IPMC devices exchanged with four monovalent cations (H+, Li+, Na+, and K+) and one ionic liquid (1‐butyl‐3‐methylimidazolium—BMIM+) were prepared, and a comprehensive investigation on how the water absorption capacity and Young's modulus vary as a function of time, relative humidity (RH), and counterion size was performed. The results revealed that the water uptake capacity is significantly higher and occurs more rapidly at higher RH levels and when the counterion's ionic radius decreases. Consequently, the time required for the device to reach osmotic equilibrium can range from 40 to 270 min, depending on the RH and counterion used. Furthermore, it was observed that the first natural frequency and Young's modulus also exhibit time‐dependent behavior. Under constant RH conditions, the mechanical properties of the IPMC can vary by up to 50% in less than 60 min. Notably, the combined results from water uptake capacity, Young's modulus, electrochemical impedance spectroscopy, and electromechanical response analyses (including blocking force, displacement, displacement rate, current, coulombic efficiency, and voltage) suggest that a morphological transformation within the polymer is likely to occur once RH exceeds 60%. This finding strengthens the hypothesis that ion migration is mainly influenced by their movement through Nafion's ionomeric channels rather than the filling of ionic agglomerates. [ABSTRACT FROM AUTHOR]

Shape-programmable materials have garnered significant attention for their ability to morph into complex three-dimensional (3D) configurations under external stimuli, with critical applications in the fields of biomedical engineering, soft robotics, and sensing technologies. A current challenge lies in determining the geometric parameters of the initial two-dimensional (2D) structure and the intensity of the external stimulus required to achieve a target 3D shape. In this work, we introduce a novel inverse design strategy based on hole-pattern engineering. Utilizing a temperature-sensitive bilayer hydrogel with differing coefficients of thermal expansion in each layer, we achieve controlled bending deformations by varying the porosity distribution in one of the layers. Drawing on the Timoshenko theory on bimetallic beam, we establish a quantitative relationship between the relative density and curvature, allowing for the hole distribution of the initial structure to be tailored to the desired curvature. We demonstrate the efficacy of our inverse design approach with several prototypical 3D structures, including variable-curvature strip and ellipsoidal surface, validated through finite element simulations and experimental trials. This strategy paves the way for advanced fabrication techniques in developing smart materials and devices with programmable shapes. [ABSTRACT FROM AUTHOR]

The purpose of the present study was to examine whether spatial or temporal prediction of the tactile stimulus contributes to tactile sensitivity. To investigate the effect of spatial prediction on tactile sensitivity, electrical stimuli were provided for the digit nerve in one of five fingers, and advanced notice of the stimulating finger was provided before the stimulus in some trials but not in others. There was no significant effect of spatial prediction on the intensity at the perceptual threshold of the digit nerve stimulus. This indicates that spatial prediction of the tactile stimulus does not influence tactile sensitivity. To examine the effect of temporal prediction, an auditory warning cue was provided 0, 1, or 10 s before the electrical stimulus to the digit nerve. The stimulus intensity at the perceptual threshold in the trials with the 1 s warning cue was lower than those with the 0 s warning cue. This indicates that temporal prediction enhances tactile sensitivity. The stimulus intensity at the perceptual threshold in the trials with the 1 s warning cue was lower than those with the 10 s warning cue. This means that the contribution of temporal prediction to the tactile sensitivity is greater as the warning cue is closer to the time of the stimulus. This finding may be explained by a defense mechanism activated when humans predict that a tactile stimulus is coming soon. [ABSTRACT FROM AUTHOR]

In this manuscript we reported the results of our studies concerning the response of vibration bands in deoxyribonucleic acid region in neuronal-like cells under exposure to static and 50 Hz electromagnetic fields using Fourier Transform Infrared spectroscopy. This technique was chosen because it is able to detect alteration of vibration bands of chemical compounds even induced by small stress agents. The aim of this study was to investigate the response of chromatin and chromosome to low intensity electromagnetic fields at values similar to manmade electromagnetic fields. The phosphate bands of asymmetric and symmetric stretching mode (representative of deoxyribonucleic acid spectral region) were observed to decrease after 3 h exposure at 1 mT (both static and 50 Hz magnetic field). Prolonging time exposure or increasing the intensity of applied magnetic field induced a low increasing in intensity of these vibration bands. This finding can be explaining assuming that chromatin uncoiling occurred at low intensity of the field and that increasing time exposure or magnetic field intensity caused an increasing of the torque on chromosome inducing an alignment along the direction of the field. [ABSTRACT FROM AUTHOR]

This study investigated the neurologic symptoms and stimulus intensities in the stimulation of deep structures and subcortical fibers with the depth electrodes. Seventeen patients with drug-refractory epilepsy who underwent functional brain mapping with the depth electrodes were enrolled. The 50 Hz electrical stimulation was applied, and the diffusion tensor image was used to identify subcortical fibers. The responsible structures and stimulus intensities for the induced neurologic symptoms were evaluated. Neurologic symptoms were induced in 11 of 17 patients. The opercular stimulation elicited the neurologic symptoms in 6 patients at the median threshold of 4.0 mA (visceral/face/hand sensory, hand/throat motor, negative motor and auditory symptoms). The insular stimulation induced the neurologic symptoms in 4 patients at the median threshold of 4.0 mA (auditory, negative motor, and sensory symptoms). The stimulation of subcortical fibers was induced in 5 of 9 patients at the median threshold of 4.5 mA. The thresholds of depth electrodes were significantly lower than those of subdural electrodes in 8 patients who used both subdural and depth electrodes and induced symptoms with both electrodes. The stimulation of depth electrodes can identify the function of deep structures and subcortical fibers with lower intensities than subdural electrodes. [ABSTRACT FROM AUTHOR]

Despite being widely assumed, the worsening impact of unpredictability on pain perception remains unclear because of conflicting empirical evidence, and a lack of systematic integration of past research findings. To fill this gap, we conducted a systematic review and meta-analysis focusing on the effect of unpredictability on pain perception. We also conducted meta-regression analyses to examine the moderating effect of several moderators associated with pain and unpredictability: stimulus duration, calibrated stimulus pain intensity, pain intensity expectation, controllability, anticipation delay, state and trait negative affectivity, sex/gender and age of the participants, type of unpredictability (intensity, onset, duration, location), and method of pain induction (thermal, electrical, mechanical pressure, mechanical distention). We included 73 experimental studies with adult volunteers manipulating the (un)predictability of painful stimuli and measuring perceived pain intensity and pain unpleasantness in predictable and unpredictable contexts. Because there are insufficient studies with patients, we focused on healthy volunteers. Our results did not reveal any effect of unpredictability on pain perception. However, several significant moderators were found, ie, targeted stimulus pain intensity, expected pain intensity, and state negative affectivity. Trait negative affectivity and uncontrollability showed no significant effect, presumably because of the low number of included studies. Thus, further investigation is necessary to clearly determine their role in unpredictable pain perception. [ABSTRACT FROM AUTHOR]

Reversible axonal swelling and brainstem auditory evoked potential (BAEP) changes were observed in standard chronic (9‐month) toxicology studies in dogs treated with ritlecitinib, an oral Janus kinase 3/tyrosine kinase expressed in hepatocellular carcinoma family kinase inhibitor, at exposures higher than the approved 50‐mg human dose. To evaluate the clinical relevance of the dog toxicity finding, this phase 2a, double‐blind study assessed BAEP changes and intraepidermal nerve fiber (IENF) histology in adults with alopecia areata treated with ritlecitinib. Patients were randomized to receive oral ritlecitinib 50 mg once daily (QD) with a 4‐week loading dose of 200 mg QD or placebo for 9 months (placebo‐controlled phase); they then entered the active‐therapy extension and received ritlecitinib 50 mg QD (with a 4‐week loading dose of 200 mg in patients switching from placebo). Among the 71 patients, no notable mean differences in change from baseline (CFB) in Waves I–V interwave latency (primary outcome) or Wave V amplitude on BAEP at a stimulus intensity of 80 dB nHL were observed in the ritlecitinib or placebo group at Month 9, with no notable differences in interwave latency or Wave V amplitude between groups. The CFB in mean or median IENF density and in percentage of IENFs with axonal swellings was minimal and similar between groups at Month 9. Ritlecitinib treatment was also not associated with an imbalanced incidence of neurological and audiological adverse events. These results provide evidence that the BAEP and axonal swelling finding in dogs are not clinically relevant in humans. [ABSTRACT FROM AUTHOR]

How is new information organized in memory? According to latent state theories, this is determined by the level of surprise, or prediction error, generated by the new information: a small prediction error leads to the updating of existing memory, large prediction error leads to encoding of a new memory. We tested this idea using a protocol in which rats were first conditioned to fear a stimulus paired with shock. The stimulus was then gradually extinguished by progressively reducing the shock intensity until the stimulus was presented alone. Consistent with latent state theories, this gradual extinction protocol (small prediction errors) was better than standard extinction (large prediction errors) in producing long-term suppression of fear responses, and the benefit of gradual extinction was due to updating of the conditioning memory with information about extinction. Thus, prediction error determines how new information is organized in memory, and latent state theories adequately describe the ways in which this occurs. [ABSTRACT FROM AUTHOR]

Preclinical assessments of pain have often relied upon behavioral measurements and anesthetized neurophysiological recordings. Current technologies enabling large-scale neural recordings, however, have the potential to unveil quantifiable pain signals in conscious animals for preclinical studies. Although pain processing is distributed across many brain regions, the anterior cingulate cortex (ACC) is of particular interest in isolating these signals given its suggested role in the affective (“unpleasant”) component of pain. Here, we explored the utility of the ACC toward preclinical pain research using head-mounted miniaturized microscopes to record calcium transients in freely moving male mice expressing genetically encoded calcium indicator 6f (GCaMP6f) under the Thy1 promoter. We verified the expression of GCaMP6f in excitatory neurons and found no intrinsic behavioral differences in this model. Using a multimodal stimulation paradigm across naive, pain, and analgesic conditions, we found that while ACC population activity roughly scaled with stimulus intensity, single-cell representations were highly flexible. We found only low-magnitude increases in population activity after complete Freund’s adjuvant (CFA) and insufficient evidence for the existence of a robust nociceptive ensemble in the ACC. However, we found a temporal sharpening of response durations and generalized increases in pairwise neural correlations in the presence of the mechanistically distinct analgesics gabapentin or ibuprofen after (but not before) CFA-induced inflammatory pain. This increase was not explainable by changes in locomotion alone. Taken together, these results highlight challenges in isolating distinct pain signals among flexible representations in the ACC but suggest a neurophysiological hallmark of analgesia after pain that generalizes to at least two analgesics. [ABSTRACT FROM AUTHOR]

Drug treatments for pain often do not outperform placebo, and a better understanding of placebo mechanisms is needed to improve treatment development and clinical practice. In a large-scale fMRI study (N = 392) with pre-registered analyses, we tested whether placebo analgesic treatment modulates nociceptive processes, and whether its effects generalize from conditioned to unconditioned pain modalities. Placebo treatment caused robust analgesia in conditioned thermal pain that generalized to unconditioned mechanical pain. However, placebo did not decrease pain-related fMRI activity in brain measures linked to nociceptive pain, including the Neurologic Pain Signature (NPS) and spinothalamic pathway regions, with strong support for null effects in Bayes Factor analyses. In addition, surprisingly, placebo increased activity in some spinothalamic regions for unconditioned mechanical pain. In contrast, placebo reduced activity in a neuromarker associated with higher-level contributions to pain, the Stimulus Intensity Independent Pain Signature (SIIPS), and affected activity in brain regions related to motivation and value, in both pain modalities. Individual differences in behavioral analgesia were correlated with neural changes in both modalities. Our results indicate that cognitive and affective processes primarily drive placebo analgesia, and show the potential of neuromarkers for separating treatment influences on nociception from influences on evaluative processes. The mechanisms underlying placebo analgesia are not fully understood. Here the authors show that a placebo treatment inducing analgesia in healthy participants reduced fMRI activity in systems related to evaluative and affective processes, but not systems related to nociceptive pain processing. [ABSTRACT FROM AUTHOR]

The object of the study is multidimensional objects. The problem solved in the study is to increase the efficiency of assessing the state of multidimensional objects, regardless of the number of dimensions of object state assessment. The subject of the study is the process of assessing the state of multidimensional objects using an advanced butterfly optimization algorithm (BOA), an advanced genetic algorithm and evolving artificial neural networks. The originality of the study is as follows: – the initial setting of butterfly agents (BA) on the plane of multidimensional objects is carried out taking into account the type of uncertainty using appropriate correction factors for the degree of awareness of nectar source locations (in our case, priority search directions); – adjusting the initial BA velocity allows determining search priority; – the fitness of BA nectar collection sites is determined, which reduces the time for assessing the state of multidimensional objects; – the possibility of global restart of the algorithm, which allows the algorithm to go beyond the current optimum and improve the exploration ability, which reduces the time for assessing the state of multidimensional objects; – the possibility of clarification at the stage of collecting nectar clusters due to ranking nectar sources by the level of stimulus intensity; – improved ability to select the best BA in comparison with traditional selection using an advanced genetic algorithm. The proposed method should be used to solve the problems of assessing the state of multidimensional objects under uncertainty and risks characterized by a high degree of complexity. The method showed a 14–16 % increase in the efficiency of assessing the state of multidimensional objects. [ABSTRACT FROM AUTHOR]

The primary goal of this study was to develop a parametric model that relates variation in stimulation of the trigeminal nerve to properties of the blink response. We measured blink responses in 17 healthy, adult participants to air puffs directed at the lateral canthus of the eye at five different, log‐spaced intensities (3.5–60 PSI). Lid position over time was decomposed into amplitude and velocity components. We found that blink amplitude was systematically related to log stimulus intensity, with the relationship well described by a sigmoidal function. The parameters of the model fit correspond to the slope of the function and the stimulus intensity required to produce half of a maximal blink response (the half‐response threshold). There was a reliable increase in the half‐response threshold for the contralateral as compared to the ipsilateral blink response. This increase was consistent across participants despite substantial individual differences in the half‐response threshold and slope parameters of the overall sensitivity function, suggesting that the laterality effect arises in the neural circuit subsequent to individual differences in sensitivity. Overall, we find that graded mechanical stimulation of the somatosensory trigeminal afferents elicits a graded response that is well described by a simple parametric model. We discuss the application of parametric measurements of the blink response to the detection of group differences in trigeminal sensitivity. There has been limited study of how variation in stimulus intensity influences the cutaneous blink response. We describe how variation in the intensity of an air puff stimulus relates to the amplitude of the blink response using a two‐parameter model. The parameters of the model capture individual differences in response, which may be used in future studies to identify population differences in trigeminal sensitivity. [ABSTRACT FROM AUTHOR]

The perception of sensory attributes is often quantified through measurements of sensitivity (the ability to detect small stimulus changes), as well as through direct judgments of appearance or intensity. Despite their ubiquity, the relationship between these two measurements remains controversial and unresolved. Here, we propose a framework in which they arise from different aspects of a common representation. Specifically, we assume that judgments of stimulus intensity (e.g., as measured through rating scales) reflect the mean value of an internal representation, and sensitivity reflects a combination of mean value and noise properties, as quantified by the statistical measure of Fisher information. Unique identification of these internal representation properties can be achieved by combining measurements of sensitivity and judgments of intensity. As a central example, we show that Weber's law of perceptual sensitivity can coexist with Stevens' power-law scaling of intensity ratings (for all exponents), when the noise amplitude increases in proportion to the representational mean. We then extend this result beyond the Weber's law range by incorporating a more general and physiology-inspired form of noise and show that the combination of noise properties and sensitivity measurements accurately predicts intensity ratings across a variety of sensory modalities and attributes. Our framework unifies two primary perceptual measurements--thresholds for sensitivity and rating scales for intensity--and provides a neural interpretation for the underlying representation. [ABSTRACT FROM AUTHOR]

In visual perception and information processing, a cascade of associations is hypothesized to flow from the structure of the visual stimulus to neural activity along the retinogeniculostriate visual system to behavior and action. Do visual perception and information processing adhere to this cascade near the beginning of life? To date, this three-stage hypothetical cascade has not been comprehensively tested in infants. In two related experiments, we attempted to expose this cascade in 6-month-old infants. Specifically, we presented infants with two levels of visual stimulus intensity, we measured electrical activity at the infant cortex, and we assessed infants' preferential looking behavior. Chromatic saturation provided a convenient stimulus dimension to test the cascade because greater saturation is known to excite increased activity in the primate visual system and is generally hypothesized to stimulate visual preference. Experiment 1 revealed that infants prefer (look longer) at the more saturated of two colors otherwise matched in hue and brightness. Experiment 2 showed increased aggregate neural cortical excitation in infants (and adults) to the more saturated of the same pair of colors. Thus, experiments 1 and 2 taken together confirm a cascade: Visual stimulation of relatively greater intensity evokes relatively greater levels of bioelectrical cortical activity which in turn is associated with relatively greater visual attention. As this cascade obtains near the beginning of life, it helps to account for early visual preferences and visual information processing. [ABSTRACT FROM AUTHOR]

Digital technologies, such as virtual or augmented reality, can potentially support neurocognitive functions of the aging populations worldwide and complement existing intervention methods. However, aging-related declines in the frontal-parietal network and dopaminergic modulation which progress gradually across the later periods of the adult lifespan may affect the processing of multisensory congruence and expectancy based contextual plausibility. We assessed hemodynamic brain responses while middle-aged and old adults experienced car-riding virtual-reality scenarios where the plausibility of vibrotactile stimulations was manipulated by delivering stimulus intensities that were either congruent or incongruent with the digitalized audio-visual contexts of the respective scenarios. Relative to previous findings observed in young adults, although highly plausible vibrotactile stimulations confirming with contextual expectations also elicited higher brain hemodynamic responses in middle-aged and old adults, this effect was limited to virtual scenarios with extreme expectancy violations. Moreover, individual differences in plausibility-related frontal activity did not correlate with plausibility violation costs in the sensorimotor cortex, indicating less systematic frontal context-based sensory filtering in older ages. These findings have practical implications for advancing digital technologies to support aging societies. [ABSTRACT FROM AUTHOR]

Anomaly detection, a data intensive task, is very important in wide application scenarios. Memristor has shown excellent performance in data intensive tasks. However, memristor used for anomaly detection has rarely been reported. In this Letter, a tantalum oxide (TaOx) memristive neuron device has been developed for anomaly detection application. TaOx, a CMOS compatible material, based memristor shows reliable threshold switching characteristics, which is suitable for constructing memristive neuron. Furthermore, the output frequency of the memristive neuron is found to be proportionate to the applied stimulus intensity and at an inflection point starts to decrease, namely, thresholding effect. Based on the thresholding effect of the neuron output, the application of the memristive neuron for anomaly detection has been simulated. The results indicate that the TaOx memristive neuron with thresholding effect shows better performance (98.78%) than the neuron without threshoding effect (90.89%) for anomaly detection task. This work provided an effective idea for developing memristive anomaly detection system. [ABSTRACT FROM AUTHOR]

Introduction/purpose: Recently, the use of transcutaneous spinal cord stimulation (TSCS) has been proposed as a viable alternative to the H-reflex. The aim of the current study was to investigate to what extent the two modes of spinal cord excitability investigation would be similarly sensitive to the well-known vibration-induced depression. Methods: Fourteen healthy participants (8 men and 6 women; age: 26.7 ± 4.8 years) were engaged in the study. The right soleus H-reflex and TSCS responses were recorded at baseline (PRE), during right Achilles tendon vibration (VIB) and following 20 min of vibration exposure (POST-VIB). Care was taken to match H-reflex and TSCS responses amplitude at PRE and to maintain effective stimulus intensities constant throughout time points. Results: The statistical analysis showed a significant effect of time for the H-reflex, with VIB (13 ± 5% of maximal M-wave (Mmax) and POST-VIB (36 ± 4% of Mmax) values being lower than PRE-values (48 ± 6% of Mmax). Similarly, TSCS responses changed over time, VIB (9 ± 5% of Mmax) and POST-VIB (27 ± 5% of Mmax) values being lower than PRE-values (46 ± 6% of Mmax). Pearson correlation analyses revealed positive correlation between H-reflex and TSCS responses PRE-to-VIB changes, but not for PRE- to POST-VIB changes. Conclusion: While the sensitivity of TSCS seems to be similar to the gold standard H-reflex to highlight the vibratory paradox, both responses showed different sensitivity to the effects of prolonged vibration, suggesting slightly different pathways may actually contribute to evoked responses of both stimulation modalities. [ABSTRACT FROM AUTHOR]

fMRI studies show activation of cerebellum during transcutaneous auricular vagal nerve stimulation (taVNS); however, there is no evidence whether taVNS induced activation of the cerebellum translates to the cerebellar closed loops involved in motor functions. We assessed the propensity of taVNS at 25 Hz (taVNS25) and 100 Hz (taVNS100) to modulate cerebello-thalamo-cortical pathways using transcranial magnetic stimulation. In our double blind within-subjects study thirty-two participants completed one visit during which cerebellar brain inhibition (CBI) was assessed at baseline (no stimulation) and in a randomized order during taVNS100, taVNS25, and sham taVNS (xVNS). Generalized linear mixed models with gamma distribution were built to assess the effect of taVNS on CBI. The estimated marginal means of linear trends during each taVNS condition were computed and compared in a pairwise fashion with Benjamini-Hochberg correction for multiple comparisons. CBI significantly increased during taVNS100 compared to taVNS25 and xVNS (p = 0.0003 and p = 0.0465, respectively). The taVNS current intensity and CBI conditioning stimulus intensity had no significant effect on CBI. taVNS has a frequency dependent propensity to modulate the cerebello-thalamo-cortical pathway. The cerebellum participates in closed-loop circuits involved in motor, cognitive, and affective operations and may serve as an entry for modulating effects of taVNS. [ABSTRACT FROM AUTHOR]

Crossmodal correspondences refer to systematic associations between stimulus attributes encountered in different sensory modalities. These correspondences can be probed in the speeded classification task where they tend to produce congruency effects. This study aimed to replicate and extend previous work conducted by Marks (1987, Experiment 3, Journal of Experimental Psychology: Human Perception and Performance, Vol. 13, No. 3, 384–394) which demonstrated a crossmodal correspondence between auditory and visual intensity attributes. Experiment 1 successfully replicates Marks' original finding that performance in a brightness classification task is affected by whether the loudness of a concurrently presented auditory distractor matches the brightness of the visual target. Furthermore, in line with the original study, we found that this effect was absent in a lightness classification task. In Experiment 2, we demonstrate that loudness–brightness correspondence is robust even when the exact stimulus input changes. This finding suggests that there is a context-dependent mapping between loudness and brightness levels, rather than an absolute mapping between any particular intensity levels. Finally, exploratory analysis using the diffusion model for conflict tasks indicated that evidence from the task-irrelevant modality generates a burst of weak, short-lived automatic activation that can bias decision-making in difficult tasks, but not in easy tasks. Our results provide further evidence for the existence of a flexible crossmodal correspondence between brightness and loudness, which might be helpful in determining one's distance to a stimulus source during the early stages of multisensory integration. Public Significance Statement: Cognitive psychology has uncovered fascinating connections between our senses, suggesting they can work together in surprising ways. We present data which confirm and extend an earlier finding that the loudness of sounds and the brightness of lights are linked in our minds. This link might improve our ability to accurately judge how far away something is. [ABSTRACT FROM AUTHOR]

The European corn borer, Ostrinia nubilalis (Hubner), relies on multimodal sensory information to find food, mates, mating and ovipositional grounds. Successful phytosanitary monitoring demands for the bait for the field traps to obtain the most reliable representation of pest abundance. Attraction to light and blend of key components of host plant odor, was tested both in the laboratory and field conditions. Ultraviolet light, which was the most effective in the wind tunnel experiments, was further tested in the field alone and in combination with bisexual lure. Bisexual lure, being attractive in the lab, as well as in the field, did not improve responses to ultraviolet in both experimental designs. All three baits attracted significantly more females than males in the field. Wind tunnel experiments revealed that ultraviolet elicited the shortest response latencies either alone or paired with the odor bait. The lack of synergistic effect between attractive light and odor stimuli is an important issue for pest monitoring. The possible reasons for the observed lack of synergy are the hierarchy of behavioral responses to different stimuli or the intensities of both stimuli are critically important for attractivity of combined stimulus and differ from separately presented ones. [ABSTRACT FROM AUTHOR]

Gamma-band activity has been the focus of considerable research in schizophrenia. Discrepancies exist regarding the integrity of the early auditory gamma-band response (EAGBR), a stimulus-evoked oscillation, and its relationship to symptoms in early disease. Variability in task design may play a role. This study examined sensitivity of the EAGBR to stimulus intensity and its relation to symptoms and functional impairments in the first-episode schizophrenia spectrum (FESz). Magnetoencephalography was recorded from 35 FESz and 40 matched healthy controls (HC) during presentation of 3 tone intensities (75 dB, 80 dB, 85 dB). MRIs were collected to localize auditory cortex activity. Wavelet-transformed single trial epochs and trial averages were used to assess EAGBR intertrial phase coherence (ITPC) and evoked power, respectively. Symptoms were assessed using the Positive and Negative Syndrome Scale. Groups did not differ in overall EAGBR power or ITPC. While HC exhibited EAGBR enhancement to increasing intensity, FESz exhibited reduced power to the 80 dB tone and, relative to HC, increased power to the 75 dB tone. Larger power and ITPC were correlated with more severe negative, thought disorganization, and resistance symptoms. Stronger ITPC was associated with impaired social functioning. EAGBR showed no overall deficit at disease onset. Rather, FESz exhibited a differential response across tone intensity relative to HC, emphasizing the importance of stimulus characteristics in EAGBR studies. Associations between larger EAGBR and more severe symptoms suggest aberrant synchronization driving overinclusive perceptual binding that may relate to deficits in executive inhibition of initial sensory activity. [ABSTRACT FROM AUTHOR]

The perceived intensity of an intense stimulus as well as the startle reflex it elicits can both be reduced when preceded by a weak stimulus (prepulse). Both phenomena are used to characterise the processes of sensory gating in clinical and non-clinical populations. The latter phenomenon, startle prepulse inhibition (PPI), is conceptualised as a measure of pre-attentive sensorimotor gating due to its observation at short latencies. In contrast, the former, prepulse inhibition of perceived stimulus intensity (PPIPSI), is believed to involve higher-order cognitive processes (e.g., attention), which require longer latencies. Although conceptually distinct, PPIPSI is often studied using parameters that elicit maximal PPI, likely limiting what we can learn about sensory gating's influence on conscious perception. Here, we tested an array of stimulus onset asynchronies (SOAs; 0–602 ms) and prepulse intensities (0–3× perceptual threshold) to determine the time course and sensitivity to the intensity of electrotactile PPIPSI. Participants were required to compare an 'unpleasant but not painful' electric pulse to their left wrist that was presented alone with the same stimulus preceded by an electric prepulse, and report which pulse stimulus felt more intense. Using a 2× perceptual threshold prepulse, PPIPSI emerged as significant at SOAs from 162 to 602 ms. We conclude that evidence of electrotactile PPIPSI at SOAs of 162 ms or longer is consistent with gating of perception requiring higher-level processes, not measured by startle PPI. The possible role of attentional processes, stimuli intensity, modality-specific differences, and methods of investigating PPIPSI further are discussed. [ABSTRACT FROM AUTHOR]

Behavioral thresholds define the lowest stimulus intensities sufficient to elicit a behavioral response. Establishment of baseline behavioral thresholds during development is critical for proper responses throughout the animal's life. Despite the relevance of such innate thresholds, the molecular mechanisms critical to establishing behavioral thresholds during development are not well understood. The acoustic startle response is a conserved behavior whose threshold is established during development yet is subsequently acutely regulated. We have previously identified a zebrafish mutant line (escapist) that displays a decreased baseline or innate acoustic startle threshold. Here, we identify a single base pair substitution on Chromosome 25 located within the coding sequence of the synaptotagmin 7a (syt7a) gene that is tightly linked to the escapist acoustic hypersensitivity phenotype. By generating animals in which we deleted the syt7a open reading frame, and subsequent complementation testing with the escapist line, we demonstrate that loss of syt7a function is not the cause of the escapist behavioral phenotype. Nonetheless, escapist mutants provide a powerful tool to decipher the overlap between acute and developmental regulation of behavioral thresholds. Extensive behavioral analyses reveal that in escapist mutants the establishment of the innate acoustic startle threshold is impaired, while regulation of its acute threshold remains intact. Moreover, our behavioral analyses reveal a deficit in baseline responses to visual stimuli, but not in the acute regulation of responses to visual stimuli. Together, this work eliminates loss of syt7a as causative for the escapist phenotype and suggests that mechanisms that regulate the establishment of behavioral thresholds in escapist larvae can operate independently from those regulating acute threshold regulation. [ABSTRACT FROM AUTHOR]

Sensory processing in the auditory brainstem can be studied with auditory brainstem responses (ABRs) across species. There is, however, a limited understanding of ABRs as tools to assess the effect of pharmacological interventions. Therefore, we set out to understand how pharmacological agents that target key transmitter systems of the auditory brainstem circuitry affect ABRs in rats. Given previous studies, demonstrating that Nrxn1α KO Sprague Dawley rats show substantial auditory processing deficits and altered sensitivity to GABAergic modulators, we used both Nrxn1α KO and wild-type littermates in our study. First, we probed how different commonly used anesthetics (isoflurane, ketamine/xylazine, medetomidine) affect ABRs. In the next step, we assessed the effects of different pharmacological compounds (diazepam, gaboxadol, retigabine, nicotine, baclofen, and bitopertin) either under isoflurane or medetomidine anesthesia. We found that under our experimental conditions, ABRs are largely unaffected by diverse pharmacological modulation. Significant modulation was observed with (i) nicotine, affecting the late ABRs components at 90 dB stimulus intensity under isoflurane anesthesia in both genotypes and (ii) retigabine, showing a slight decrease in late ABRs deflections at 80 dB stimulus intensity, mainly in isoflurane anesthetized Nrxn1α KO rats. Our study suggests that ABRs in anesthetized rats are resistant to a wide range of pharmacological modulators, which has important implications for the applicability of ABRs to study auditory brainstem physiology. [ABSTRACT FROM AUTHOR]

There are many different kinds of 'phantom' percepts but it is unknown whether they are united by common mechanisms. For example, synaesthesia (e.g., numbers evoking colour) and hallucinations appear conceptually and phenomenologically similar: both result in a percept that does not have an environmental correlate. Here, people with synaesthesia (n = 66) performed a conditioned hallucinations paradigm known to be sensitive to hallucination susceptibility, and we asked whether synaesthetes would show the same behavioural profile as hallucinators in this task. Repeated pairing of checkerboards with tones, and gratings with colours encourages the participant to draw on prior knowledge when asked to report on the presence of the difficult-to-detect target stimulus. Synaesthetes show increased modelled expectancies for the stimulus association across the board, resulting in a higher number of detections at all stimulus intensities. This is in contrast to the pattern observed in hallucinators, who weigh their prior beliefs more strongly than controls, giving rise to more conditioned hallucinations. Results indicate that fundamentally different perceptual processes may be at the core of these seemingly similar experiences. [ABSTRACT FROM AUTHOR]

Hypertension is a frequent condition in untrained middle-aged to older adults, who form the core group of whole-body electromyostimulation (WB-EMS) applicants. So far, the acute effects of varying impulse intensities on blood pressure responses have not been evaluated in normo- and hypertensive people. Thirteen hypertensive and twelve normotensive overweight WB-EMS novices, 40-70 years old, conducted the same WB-EMS protocol (20 min, bipolar, 85 Hz, 350 µs, 4 s impulse-4 s rest; combined with easy movements) with increasing impulse intensity (low, moderate, advanced) per session. Mean arterial blood pressure (MAP) as determined by automatic sphygmomanometry rose significantly (p < .001) from rest, 5 min pre-WB-EMS to immediately pre-WBEMS assessment. Of importance, a 20-min WB-EMS application does not increase MAP further. In detail, maximum individual MAP does not exceed 128 mmHg (177 mmHg systolic or 110 mmHg diastolic) in any case. Two-min post-WB-EMS, MAP was significantly lower (p = .016) compared to immediately pre-WB-EMS. In contrast, heart rate increased significantly from immediately pre to immediately post-exercise (p < .001), though individual peak values did not exceed 140 beats/min-1 and heart rate decreased rapidly (p < .001) post-exercise. No significant differences in MAP and HR kinetics were observed for impulse intensity categories or hypertensive status. In summary, largely independently of impulse intensity and status, the acute effect of WB-EMS on MAP in novice applicants seem to be largely negligible. Although definite evidence might not have been provided by the present study, we conclude that hypertension, at least under treatment, should not be considered as a barrier for WB-EMS application in moderately old or older cohorts. [ABSTRACT FROM AUTHOR]

Previous studies on the potential effects of unpredictability on pain perception and its neural correlates yielded divergent results. This study examined whether this may be explained by differences in acquired expectations. We presented 41 healthy volunteers with laser heat stimuli of different intensities. The stimuli were preceded either by predictable low, medium, or high cues or by unpredictable low–medium, medium–high, or low–high cues. We recorded self-reports of pain intensity and unpleasantness and laser-evoked potentials (LEPs). Furthermore, we investigated whether dynamic expectations that evolved throughout the experiment based on past trials were better predictors of pain ratings than fixed (nonevolving) expectations. Our results replicate previous findings that unpredictable pain is higher than predictable pain for low-intensity stimuli but lower for high-intensity stimuli. Moreover, we observed higher ratings for the medium–high unpredictable condition than the medium–low unpredictable condition, in line with an effect of expectation. We found significant interactions (N1, N2) for the LEP components between intensity and unpredictability. However, the few significant differences in LEP peak amplitudes between cue conditions did not survive correction for multiple testing. In line with predictive coding perspectives, pain ratings were best predicted by dynamic expectations. Surprisingly, expectations of reduced precision (increased variance) were associated with lower pain ratings. Our findings provide strong evidence that (dynamic) expectations contribute to the opposing effects of unpredictability on pain perception; therefore, we highlight the importance of controlling for them in pain unpredictability manipulations. We also suggest to conceptualize pain expectations more often as dynamic constructs incorporating previous experiences. [ABSTRACT FROM AUTHOR]

Introspection is a fundamental part of our mental lives. Nevertheless, its reliability and its underlying cognitive architecture have been widely disputed. Here, I propose a principled way to model introspection. By using time-tested principles from signal detection theory (SDT) and extrapolating them from perception to introspection, I offer a new framework for an introspective signal detection theory (iSDT). In SDT, the reliability of perceptual judgements is a function of the strength of an internal perceptual response (signal-to-noise ratio), which is, to a large extent, driven by the intensity of the stimulus. In parallel to perception, iSDT models the reliability of introspective judgements as a function of the strength of an internal introspective response (signal-to-noise ratio), which is, to a large extent, driven by the intensity of conscious experiences. Thus, by modelling introspection after perception, iSDT can calibrate introspection's reliability across a whole range of contexts. iSDT offers a novel, illuminating way of thinking about introspection and the cognitive processes that support it. [ABSTRACT FROM AUTHOR]

A vital heuristic used when making judgements on whether audio-visual signals arise from the same event, is the temporal coincidence of the respective signals. Previous research has highlighted a process, whereby the perception of simultaneity rapidly recalibrates to account for differences in the physical temporal offsets of stimuli. The current paper investigated whether rapid recalibration also occurs in response to differences in central arrival latencies, driven by visual-intensity-dependent processing times. In a behavioural experiment, observers completed a temporal-order judgement (TOJ), simultaneity judgement (SJ) and simple reaction-time (RT) task and responded to audio-visual trials that were preceded by other audio-visual trials with either a bright or dim visual stimulus. It was found that the point of subjective simultaneity shifted, due to the visual intensity of the preceding stimulus, in the TOJ, but not SJ task, while the RT data revealed no effect of preceding intensity. Our data therefore provide some evidence that the perception of simultaneity rapidly recalibrates based on stimulus intensity. [ABSTRACT FROM AUTHOR]