Stimulus Parameters Research Articles

Averaging method for the existence of singular canards in a two-cell inhibitory neural network

Abstract Studies of firing rate neuronal competition models, as observed in binocular rivalry, showed that the variation of the stimulus parameters can lead to rich and interesting dynamics. We use the two-cell inhibitory neural network model to address the canards accompanied by the L^s-typed mixed-mode oscillations (MMOs). Specifically, we prove the existence and asymptotic expression of canards for this two-cell model by the average method. Meanwhile, our simulation indicates that the results are in accordance with the theory. Our solution can provide ideas for determining and selecting weights in model fusion of machine learning.

Visual short-term memory for crossed and uncrossed binocular disparities.

Previous work on visual short-term memory (VSTM) has encompassed various stimulus attributes including spatial frequency, color, and contrast, revealing specific time courses and a dependence on stimulus parameters. This study investigates visual short-term memory for binocular depth, using dynamic random dot stereograms (DRDS) featuring disparity planes in front of or behind the plane of fixation. In a delayed match-to-sample paradigm, we employed four distinct reference disparities (17.5', 28.8' either crossed or uncrossed) at two contrast levels (20%, 80%), spanning interstimulus intervals (ISI) of up to 4 s. Test stimuli represented a range of equally spaced values centered around the reference disparity of the ongoing trial. In addition, the impact of a memory masking stimulus was also tested in a separate experiment. Accuracy and point of subjective equality (PSE) served as performance markers. The performance, indicated by the accuracy of responses, was better for smaller reference disparities (±17.5') compared to larger ones (±28'), but both deteriorated as a function of ISI. The PSE demonstrated a consistent shift with increasing ISIs, irrespective of the magnitude of the initial disparity, converging gradually toward the range of 20-22' and deviating from the reference disparity. Notably, the influence of masking stimuli on the PSE was more marked when the mask disparity diverged from the reference value. The findings from our study indicate that the retention of absolute disparity in memory is imprecise, it deteriorates with retention time or due to perturbation by dissimilar masking stimuli. As a result, the memory trace is gradually replaced by a default depth value. This value could potentially signify an optimal point within low-level perceptual memory, however, our results are better explained by perceptual averaging whereby the visual system computationally derives a statistical summary of the presented disparities over time. The latter mechanism would aid in the computation of relative disparity in a dynamically changing environment.

A Variable-Stimulus Distortion Product Otoacoustic Emission Screening Method to Match Cochlear Place-Specific Properties.

Distortion product otoacoustic emissions (DPOAEs) are a popular screening tool for hearing loss in specific populations (e.g., newborns). Current screening protocols use stimulus conditions that are agnostic to local mechanical properties of the cochlea and are also limited to a narrow frequency range. We have recently reported locally optimized stimulus frequency ratio and level combinations for recording DPOAEs up to stimulus frequencies of 19 kHz. In normally functioning cochlea, optimized stimuli improved the signal to noise ratios and allowed the registration of higher DPOAE levels, especially at higher frequencies. The purpose of this study was to evaluate the clinical performance of these physiologically motivated, locally appropriate, stimulus parameters for a screening application to identify the presence of hearing loss. Subjects were 24 adults with sensorineural hearing loss and 31 adults with normal hearing. The cubic DPOAE was measured and analyzed up to frequencies of 16 kHz using a range of stimulus conditions. Receiver operating characteristic curves were used to identify stimulus combinations most sensitive to screening for hearing loss. Receiver operating characteristic curves demonstrated improved test efficacy for hearing loss detection when using stimulus frequency ratios and levels that are frequency-dependent and consistent with known mechanical properties of the cochlea. We propose a new DPOAE recording paradigm (variable-stimuli DP) using stimuli aligned to local cochlear properties which may improve early and accurate detection of decline in cochlear function.

Frequency-of-seeing curves (psychometric functions) for perimetric stimuli in age-related macular degeneration.

Frequency-of-seeing (FoS) curves (psychometric functions) for perimetric stimuli have been widely used in computer simulations of new visual field test procedures. FoS curves for age-related macular degeneration (AMD) are not available in the literature and are needed for the development of improved microperimetry test procedures, which are of particular interest for use as clinical trial endpoints. Data were refitted from a previous study to generate FoS curves for 20 participants with AMD, each tested at nine locations within the central 10°. Stimulus parameters, background luminance and dB scale were matched to the MAIA-2 microperimeter, and stimuli were presented in a method of constant stimuli to build up FoS curves over multiple runs. FoS curves were fitted with a modified cumulative Gaussian function. The relationship between sensitivity and slope of fitted FoS curves was modelled by robust linear regression, producing models both with and without an eccentricity parameter. FoS curves were satisfactorily fitted to data from 174 visual field locations in 20 participants (age 65-83 years, 11 female). Each curve was made up of a median of 243 (range 177-297) stimulus presentations over a median of 12 (range 9-32) levels. Median sensitivity was 25.5 dB (range 3.8-31.4 dB). The median slope (SD of fitted function) was 1.6 dB (range 0.5-8.5 dB). As in previous studies of other conditions, the slope of fitted FoS curves increased as sensitivity decreased (p < 0.001). FoS are provided for participants with AMD, as well as models of the relationship between sensitivity and slope. These fitted models and data may be useful for computer simulation studies of microperimetry procedures. Full details of the fitted curves are provided as supporting information.

A meta-analysis of the effects of transcranial direct current stimulation combined with cognitive training on working memory in healthy older adults.

Working memory (WM) loss, which can lead to a loss of independence, and declines in the quality of life of older adults, is becoming an increasingly prominent issue affecting the ageing population. Transcranial direct current stimulation (tDCS), a non-invasive brain stimulation technique, is emerging as a potential alternative to pharmacological treatments that shows promise for enhancing WM capacity and May enhance the effects of cognitive training (CT) interventions. The purpose of this meta-analysis was to explore how different tDCS protocols in combination with CT enhanced WM in healthy older adults. Randomized controlled trials (RCTs) exploring the effects of tDCS combined with CT on WM in healthy older adults were retrieved from the Web of Science, PubMed, Embase, Scopus and the Cochrane Library databases. The search time period ranged from database inception to January 15, 2024. Methodological quality of the trials was assessed using the risk-of-bias criteria for RCTs from the Cochrane Collaboration Network, and RevMan 5.3 (Cochrane, London, United Kingdom) was used for the meta-analysis of the final literature outcomes. Six RCTs with a total of 323 participants were ultimately included. The results of the meta-analysis show that tDCS combined with CT statistically significantly improves WM performance compared to the control sham stimulation group in healthy older adults [standard mean difference (SMD) = 0.35, 95% CI: 0.11-0.59, I 2 = 0%, Z = 2.86, p = 0.004]. The first subgroup analysis indicated that, when the stimulus intensity was 2 mA, a statistically significant improvement in WM performance in healthy older adults was achieved (SMD = 0.39, 95% CI: 0.08-0.70, I 2 = 6%, Z = 2.46, p = 0.01). The second subgroup analysis showed that long-term intervention (≥ 10 sessions) with tDCS combined with CT statistically significantly improved WM compared to the control group in healthy older adults (SMD = 0.72, 95% CI: 0.22-1.21, I 2 = 0%, Z = 2.85, p = 0.004). tDCS combined with CT statistically significantly improves WM in healthy older adults. For the stimulus parameters, long-term interventions (≥ 10 sessions) with a stimulation intensity of 2 mA are the most effective.

Temperature modulates the tuning properties of small target motion detector neurons in the dragonfly visual system

Dragonflies are poikilothermic animals with limited thermoregulation; therefore, their entire bodies, including the brain, experience a range of temperatures during their daily activities.1,2 These flying insects exhibit hunting prowess, pursuing prey or conspecifics whether in direct sunlight or under the cover of cloud.3,4 Likely to underlie these aerobatic feats are the small target motion detector (STMD) neurons.5 These visual neurons are sensitive to target contrast and tuned to the target's size and velocity, with some neurons exhibiting complex predictive and selective properties, well suited for prey interception and feeding amid swarms.3,4,6,7,8,9 Increased temperature can modulate the biochemical processes underlying neuronal processing, increasing sensitivity and quickening the responsiveness of insect photoreceptors and downstream optic flow neurons,10,11,12 while in other neuronal pathways, compensatory processes have been shown to account for temperature changes.13,14 We determined the ethological range of temperatures experienced by the dragonfly, Hemicordulia tau, in its natural environment. Across this behaviorally relevant range, we showed increased temperatures having a large 8.7-fold increase in the contrast sensitivity of STMD neurons. However, suppression of responses to larger targets was unaltered. STMD tuning for target velocities was changed remarkably, not only increasing the optimum but extending the fastest velocities encoded by an order of magnitude. These results caution against interpreting functionality underlying spike rates at constrained, experimental temperatures. Moreover, they raise intriguing new questions about how information is represented within the brain of these flying insects, given the relationship between visual stimulus parameters and neuronal activity varies so dramatically depending on current environmental conditions.

Individual peak alpha frequency correlates with visual temporal resolution, but only under specific task conditions.

The study of alpha band oscillations in the brain is a popular topic in cognitive neuroscience. A fair amount of research in recent years has focused on the potential role these oscillations may play in the discrete sampling of continuous sensory information. In particular, the question of whether or not peak frequency in the alpha band is linked with the temporal resolution of visual perception is a topic of ongoing debate. Some studies have reported a correlation between the two, whereas others were unable to observe a link. It is unclear whether these conflicting findings are due to differing methodologies and/or low statistical power, or due to the absence of a true relationship. Replication studies are needed to gain better insight into this matter. In the current study, we replicated an experiment published in a 2015 paper by Samaha and Postle. Additionally, we expanded on this study by adding an extra behavioural task, the critical flicker fusion task, to investigate if any links with peak alpha frequency are generalizable across multiple measures for visual temporal resolution. We succeeded in replicating some, but not all of Samaha and Postle's findings. Our partial replication suggests that there may be a link between visual temporal resolution and peak alpha frequency. However, this relationship may be very small and only apparent for specific stimulus parameters. The correlations found in our study did not generalize to other behavioural measures for visual temporal resolution.

Electrical-Light Coordinately Modulated Synaptic Memristor Based on Ti3C2 MXene for Near-Infrared Artificial Vision Applications.

Emerging optoelectronic memristive devices with high parallelism and low-power consumption have made neuromorphic computing hardware a tangible reality. The coordination of conductivity regulation through both electrical and light signals is pivotal for advancing the development of synaptic memristors with brainlike functionalities. Here, an artificial visual synapse is presented with the Ti3C2 MXene memristor which demonstrates not only the nonvolatile memory effect (Set/Reset: 0.58/-0.55 V; Retention: >103 s) and sustained multistage conductivity, but also facile modulation of both electrical- and light-stimulated synaptic behaviors. By adjusting the stimulus parameters, the Ti3C2 MXene enables the realization of biosynaptic excitatory postsynaptic current, sustained conductivity, stable long-term facilitation/depression, paired pulse facilitation, spiking-timing-dependent plasticity, and experiential learning. Particularly, benefiting from the distinguishable photoconductive and memory effects of multiple near-infrared intensities (7-13 mW/cm2), potential applications in visual nociceptive perception ("threshold", "noadaption", "relaxation") and imaging (e.g., "Superman" cartoon character) in infrared environments are well achieved in such Ti3C2 MXene memristors. These results hold significant implications for the future advancement of integrated optoelectronic sensing, memory, nociception, and imaging systems.

Methodologies to elicit and record pudendal somatosensory evoked potentials in adult humans: A systematic review

ObjectiveThe 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. MethodsWe 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. Results132 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. ConclusionsOur 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. SignificanceWe 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.

Infant Cervical Vestibular Evoked Myogenic Potentials: A Scoping Review.

Children diagnosed with hearing loss typically demonstrate increased rates of vestibular loss as compared with their peers, with hearing within normal limits. Decreased vestibular function is linked with delays in gross motor development, acquisition of gross motor skills, and academic challenges. Timely development of sitting and walking gross motor skills aids in the progress of environmental exploratory activities, which have been tied to cognitive, language, and vocabulary development. Considering the time-sensitive development of gross motor skills and cognitive, language, and vocabulary development, identifying vestibular loss in infancy can support early intervention. This scoping review analyzes stimulus, recording, and participant factors relevant to assessing cervical vestibular evoked myogenic potentials (cVEMPs) in the infant population. The scoping literature review was conducted on literature published between 2000 and 2023, focusing on articles assessing cVEMPs in infants. Two authors independently followed Preferred Reporting Items for Systematic and Meta-Analysis guidelines for title and abstract screening, full-text review, data extraction, and quality assessments. Sixteen articles meeting the inclusion criteria were included in the analysis. The existing literature lacks consensus regarding stimulus and recording parameters for measuring infant cVEMPs. In addition, the review reveals a decrease in cVEMP response occurrence rates with the severity of hearing loss, especially in cases of severe to profound hearing loss, compared with mild to moderate sensorineural hearing loss in infants. This scoping review demonstrates the increasing use of cVEMP as a reliable tool for objectively assessing infant vestibular function. The lack of consensus in stimulus and recording parameters emphasizes the need for systematic research to establish an evidence-based protocol for cVEMP measurements in infants. Such a protocol will ensure the reliable measurement of cVEMPs in infants and enhance the effectiveness of cVEMP as part of the infant vestibular test battery. In addition, there is a necessity for a comprehensive large-scale study to evaluate the practicality and feasibility of implementing vestibular screening protocols for infants diagnosed with sensorineural hearing loss in the United States.

The application value of H-reflex induced by electrical stimulation of the sacral nerve at the S3 foramen in stimulus parameter programming

The application value of H-reflex induced by electrical stimulation of the sacral nerve at the S3 foramen in stimulus parameter programming

The impact of mechanical stress on anatomy, morphology, and gene expression in Urtica dioica L.

Main conclusionMechanical stress induces distinct anatomical, molecular, and morphological changes in Urtica dioica, affecting trichome development, gene expression, and leaf morphology under controlled conditionsThe experiments were performed on common nettle, a widely known plant characterized by high variability of leaf morphology and responsiveness to mechanical touch. A specially constructed experimental device was used to study the impact of mechanical stress on Urtica dioica plants under strictly controlled parameters of the mechanical stimulus (touching) and environment in the growth chamber. The general anatomical structure of the plants that were touched was similar to that of control plants, but the shape of the internodes' cross section was different. Stress-treated plants showed a distinct four-ribbed structure. However, as the internodes progressed, the shape gradually approached a rectangular form. The epidermis of control plants included stinging, glandular and simple setulose trichomes, but plants that were touched had no stinging trichomes, and setulose trichomes accumulated more callose. Cell wall lignification occurred in the older internodes of the control plants compared to stress-treated ones. Gene analysis revealed upregulation of the expression of the UdTCH1 gene in touched plants compared to control plants. Conversely, the expression of UdERF4 and UdTCH4 was downregulated in stressed plants. These data indicate that the nettle's response to mechanical stress reaches the level of regulatory networks of gene expression. Image analysis revealed reduced leaf area, increased asymmetry and altered contours in touched leaves, especially in advanced growth stages, compared to control plants. Our results indicate that mechanical stress triggers various anatomical, molecular, and morphological changes in nettle; however, further interdisciplinary research is needed to better understand the underlying physiological mechanisms.

Reliable Long-Term Serial Evaluation of Cochlear Function Using Pulsed Distortion-Product Otoacoustic Emissions: Analyzing Levels and Pressure Time Courses.

To date, there is no international standard on how to use distortion-product otoacoustic emissions (DPOAEs) in serial measurements to accurately detect changes in the function of the cochlear amplifier due, for example, to ototoxic therapies, occupational noise, or the development of regenerative therapies. The use of clinically established standard DPOAE protocols for serial monitoring programs appears to be hampered by multiple factors, including probe placement and calibration effects, signal-processing complexities associated with multiple sites of emission generation as well as suboptimal selection of stimulus parameters. Pulsed DPOAEs were measured seven times within 3 months for f2 = 1 to 14 kHz and L2 = 25 to 80 dB SPL in 20 ears of 10 healthy participants with normal hearing (mean age = 32.1 ± 9.7 years). L1 values were computed from individual optimal-path parameters derived from the corresponding individual DPOAE level map in the first test session. Three different DPOAE metrics for evaluating the functional state of the cochlear amplifier were investigated with respect to their test-retest reliability: (1) the interference-free, nonlinear-distortion component level (LOD), (2) the time course of the DPOAE-envelope levels, LDP(t), and (3) the squared, zero-lag correlation coefficient () between the time courses of the DPOAE-envelope pressures, pDP(t), measured in two sessions. The latter two metrics include the two main DPOAE components and their state of interference. Collated over all sessions and frequencies, the median absolute difference for LOD was 1.93 dB and for LDP(t) was 2.52 dB; the median of was 0.988. For the low (f2 = 1 to 3 kHz), mid (f2 = 4 to 9 kHz), and high (f2 = 10 to 14 kHz) frequency ranges, the test-retest reliability of LOD increased with increasing signal to noise ratio (SNR). On the basis of the knowledge gained from this study on the test-retest reliability of pulsed DPOAE signals and the current literature, we propose a DPOAE protocol for future serial monitoring applications that takes into account the following factors: (1) separation of DPOAE components, (2) use of individually optimal stimulus parameters, (3) SNR of at least 15 dB, (4) accurate pressure calibration, (5) consideration of frequency- and level-dependent test-retest reliabilities and corresponding reference ranges, and (6) stimulus levels L2 that are as low as possible with sufficient SNR to capture the nonlinear functional state of the cochlear amplifier operating at its highest gain.

Strength Simulator Codes for Different Age Groups Considering Physiological Processes of Adaptation in Conditions of Strength Fitness

Topicality. Determination of optimal load parameters in fitness, based on age-related physiological features and adaptive changes of the neuromuscular system, is one of the most debated issues among leading scientists in this field. The research purpose was to develop models of code combinations for strength training of different age groups, considering physiological processes of human body adaptation to a stressful physical stimulus in the conditions of strength fitness. Methods. A comparative analysis of the research results on the effectiveness of using the optimal combination between the parameters of an external physical stimulus and the physiological features of the human body adaptive reactions has been used over the research. The results. It was established that in the process of developing code combinations for different age groups` strength training, the nature of the physiological reactions of their neuromuscular system to a stressful stimulus depend on the features of the load regime and the structure of the exercise program. For adolescence, considering the peculiarities of the physiological process of adaptation, it is used of moderate-intensity activity in combination with a complex of isolation exercises that promotes the processes of intra-muscular and inter-muscular coordination. For youth, in the process of developing code combinations aimed at the development of the main types of strength, the entire range of load modes is actively used. Particular attention is paid to stimuli that contribute to increasing the number of active (FF) motor units. In adulthood, especially in the second period, the content of code combinations to increase strength capabilities changes significantly. In the vast majority, this applies to the parameters of the intensity of load modes, the use of which will selectively affect the hypertrophy of a certain type of muscle fibers within intermuscular coordination. For the elderly, in the process of developing code combinations for strength training, priority is given to the selective activity of agonists during moderate-intensity isolated exercises. Findings. Strength Simulator codes considering physiological processes of the neuromuscular system adaptation to a stressful physical stimulus, is one of the innovative mechanisms for improving the training program of different age groups in the conditions of strength fitness.

Revolutionizing motor dysfunction treatment: A novel closed-loop electrical stimulator guided by multiple motor tasks with predictive control

Functional electrical stimulation (FES) has been demonstrated as a viable method for addressing motor dysfunction in individuals affected by stroke, spinal cord injury, and other etiologies. By eliciting muscle contractions to facilitate joint movements, FES plays a crucial role in fostering the restoration of motor function compromised nervous system. In response to the challenge of muscle fatigue associated with conventional FES protocols, a novel biofeedback electrical stimulator incorporating multi-motor tasks and predictive control algorithms has been developed to enable adaptive modulation of stimulation parameters. The study initially establishes a Hammerstein model for the stimulated muscle group, representing a time-varying relationship between the stimulation pulse width and the root mean square (RMS) of the surface electromyography (sEMG). An online parameter identification algorithm utilizing recursive least squares is employed to estimate the time-varying parameters of the Hammerstein model. Predictive control is then implemented through feedback corrections based on the comparison between predicted and actual outputs, guided by an optimization objective function. The integration of predictive control and roll optimization enables closed-loop control of muscle stimulation. The motor training tasks of elbow flexion and extension, wrist flexion and extension, and five-finger grasping were selected for experimental validation. The results indicate that the model parameters were accurately identified, with a RMS error of 3.83 % between actual and predicted values. Furthermore, the predictive control algorithm, based on the motor tasks, effectively adjusted the stimulus parameters to ensure that the stimulated muscle groups can achieve the desired sEMG characteristic trajectory. The biofeedback electrical stimulator that was developed has the potential to assist patients experiencing motor dysfunction in achieving the appropriate joint movements. This research provides a foundation for a novel intelligent electrical stimulation model.

Development of Biomarkers Potentially Sensitive to Early Psychosis Using Mismatch Negativity (MMN) to Complex Pattern Deviations.

Infrequent stimulus deviations from repetitive sequences elicit mismatch negativity (MMN) even passively, making MMN practical for clinical applications. Auditory MMN is typically elicited by a change in one (or more) physical stimulus parameters (eg, pitch, duration). This lower-order simple MMN (sMMN) is impaired in long-term schizophrenia. However, sMMN contains activity from release from stimulus adaptation, clouding its face validity as purely deviance-related. More importantly, it is unreliably reduced in samples of first-episode psychosis, limiting its utility as a biomarker. Complex pattern-deviant MMN (cMMN) tasks, which elicit early and late responses, are based on higher-order abstractions and better isolate deviance detection. Their abstract nature may increase the sensitivity to processing deficits in early psychosis. However, both the early and late cMMNs are small, limiting separation between healthy and psychotic samples. In 29 healthy individuals, we tested a new dual-rule cMMN paradigm to assess additivity of deviance. Sounds alternated lateralization between left and right, and low and high pitches, creating a left-low, right-high alternating pattern. Deviants were a repeated left-low, violating lateralization and pitch patterns. Early and late cMMNs on the dual-rule task were significantly larger than those on the one-rule extra tone cMMN task (P < .05). Further, the dual-rule early cMMN was not significantly smaller than pitch or duration sMMNs (P > .48, .28, respectively). These results demonstrate additivity for cMMN pattern-violating rules. This increase in cMMN amplitude should increase group difference effect size, making it a prime candidate for a biomarker of disease presence at first psychotic episode, and perhaps even prior to the emergence of psychosis.

Bimodal moment-by-moment coupling in perceptual multistability.

Multistable perception occurs in all sensory modalities, and there is ongoing theoretical debate about whether there are overarching mechanisms driving multistability across modalities. Here we study whether multistable percepts are coupled across vision and audition on a moment-by-moment basis. To assess perception simultaneously for both modalities without provoking a dual-task situation, we query auditory perception by direct report, while measuring visual perception indirectly via eye movements. A support-vector-machine (SVM)-based classifier allows us to decode visual perception from the eye-tracking data on a moment-by-moment basis. For each timepoint, we compare visual percept (SVM output) and auditory percept (report) and quantify the co-occurrence of integrated (one-object) or segregated (two-objects) interpretations in the two modalities. Our results show an above-chance coupling of auditory and visual perceptual interpretations. By titrating stimulus parameters toward an approximately symmetric distribution of integrated and segregated percepts for each modality and individual, we minimize the amount of coupling expected by chance. Because of the nature of our task, we can rule out that the coupling stems from postperceptual levels (i.e., decision or response interference). Our results thus indicate moment-by-moment perceptual coupling in the resolution of visual and auditory multistability, lending support to theories that postulate joint mechanisms for multistable perception across the senses.

Efficacy of Altered Frequency Dynamics of Ocular-Vestibular Evoked Myogenic Potentials in Type 2 Diabetes Mellitus

Purpose: The study aims to address the gap in understanding the relationship between type 2 diabetes mellitus (T2DM) and vestibular dysfunction, particularly focusing on how T2DM may affect the tuning of the vestibular system. Specifically, the investigation aims to explore the impact of stimulus parameters, particularly stimulus frequency, on ocular vestibular evoked myogenic potentials (oVEMP) in individuals with T2DM.Methods: A case-control study design was used, utilizing non-probability sampling. All participants underwent routine audiological and vestibular evaluations before inclusion in the study. oVEMP’s were compared across 40 healthy individuals (group A) and 40 individuals with T2DM (group B) at 500 Hz, 1 KHz, and 2 KHz.Results: In group A, all 80 participants exhibited oVEMP responses across all frequencies in both ears, while in group B, consisting of individuals with T2DM, response rates were slightly lower, ranging from 70% to 77.5% across frequencies. Statistical analysis revealed significant amplitude differences at all frequencies tested in type 2 diabetic ears compared to healthy ears, although amplitude remained consistent within type 2 diabetic ears. Latencies (first negative [N1] and first positive [P1]) were consistent across groups, with delays observed in P1 latency, particularly noticeable at higher frequencies, both in healthy and type 2 diabetic ears. Gender didn't affect oVEMP frequency dynamics in any of the groups.Conclusion: Diabetes may create an impact in the functioning of otolith organs, the vestibular branch of eighth cranial nerve, and their innervations. VEMP evaluates both the sacculo-collic and utriculo-ocular pathways to detect changes in the functions of vestibular organs. Therefore, it's crucial to consider diabetes when conducting vestibular diagnosis or treatment.

Modulatory Effects on Laminar Neural Activity Induced by Near-Infrared Light Stimulation with a Continuous Waveform to the Mouse Inferior Colliculus In Vivo.

Infrared neural stimulation (INS) is a promising area of interest for the clinical application of a neuromodulation method. This is in part because of its low invasiveness, whereby INS modulates the activity of the neural tissue mainly through temperature changes. Additionally, INS may provide localized brain stimulation with less tissue damage. The inferior colliculus (IC) is a crucial auditory relay nucleus and a potential target for clinical application of INS to treat auditory diseases and develop artificial hearing devices. Here, using continuous INS with low to high-power density, we demonstrate the laminar modulation of neural activity in the mouse IC in the presence and absence of sound. We investigated stimulation parameters of INS to effectively modulate the neural activity in a facilitatory or inhibitory manner. A mathematical model of INS-driven brain tissue was first simulated, temperature distributions were numerically estimated, and stimulus parameters were selected from the simulation results. Subsequently, INS was administered to the IC of anesthetized mice, and the modulation effect on the neural activity was measured using an electrophysiological approach. We found that the modulatory effect of INS on the spontaneous neural activity was bidirectional between facilitatory and inhibitory effects. The modulatory effect on sound-evoked responses produced only an inhibitory effect to all examined stimulus intensities. Thus, this study provides important physiological evidence on the response properties of IC neurons to INS. Overall, INS can be used for the development of new therapies for neurological disorders and functional support devices for auditory central processing.

Comprehensive software suite for functional analysis and synaptic input mapping of dendritic spines imaged in vivo.

Advances in genetically encoded sensors and two-photon imaging have unlocked functional imaging at the level of single dendritic spines. Synaptic activity can be measured in real time in awake animals. However, tools are needed to facilitate the analysis of the large datasets acquired by the approach. Commonly available software suites for imaging calcium transients in cell bodies are ill-suited for spine imaging as dendritic spines have structural characteristics distinct from those of the cell bodies. We present an automated tuning analysis tool (AUTOTUNE), which provides analysis routines specifically developed for the extraction and analysis of signals from subcellular compartments, including dendritic subregions and spines. Although the acquisition of in vivo functional synaptic imaging data is increasingly accessible, a hurdle remains in the computation-heavy analyses of the acquired data. The aim of this study is to overcome this barrier by offering a comprehensive software suite with a user-friendly interface for easy access to nonprogrammers. We demonstrate the utility and effectiveness of our software with demo analyses of dendritic imaging data acquired from layer 2/3 pyramidal neurons in mouse V1 in vivo. A user manual and demo datasets are also provided. AUTOTUNE provides a robust workflow for analyzing functional imaging data from neuronal dendrites. Features include source image registration, segmentation of regions-of-interest and detection of structural turnover, fluorescence transient extraction and smoothing, subtraction of signals from putative backpropagating action potentials, and stimulus and behavioral parameter response tuning analyses. AUTOTUNE is open-source and extendable for diverse functional synaptic imaging experiments. The ease of functional characterization of dendritic spine activity provided by our software can accelerate new functional studies that complement decades of morphological studies of dendrites, and further expand our understanding of neural circuits in health and in disease.