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• Intensity-dependence of auditory-evoked potentials present early surrogate marker for post-stroke depression • Early intensity-dependence of auditory-evoked potentials increased in later depressed stroke patients • Early intensity-dependence of auditory-evoked potentials correlates with depressive symptoms of all stroke patients Post-stroke depression (PSD) is a common stroke complication, associated with severe physical and cognitive impairment. Low central serotonergic tone, associated with depression, inversely correlates with the intensity-dependence of auditory-evoked potentials (IDAP). Aim of this study was to investigate IDAP's usability as early surrogate marker for PSD development by assessing the correlation between IDAP early after stroke and the occurrence of PSD from 4 weeks after stroke. We assessed auditory-evoked potentials (AEP) and depressive symptoms using the Montgomery-Åsberg Depression Rating Scale (MADRS) at day 1 – 3 and > 30 after stroke onset. IDAP was calculated as the linear slope of the N1-P2 amplitude/stimulus intensity function (ASF). 37 patients completed the study. We diagnosed 7 patients with PSD, defined as MADRS-score ≥ 7 at follow-up. The PSD group showed significantly steeper ASF slopes at admission compared with the non-depressed group (p = 0.007). We also found a positive correlation between ASF slopes on first and MADRS-scores on last measurement point for all stroke patients as a group (p = 0.007). The study findings support the hypothesis that IDAP can predict the development of depressive symptoms following stroke and may therefore serve as an early surrogate marker for PSD. This is the first longitudinal study to assess the relationship between IDAP and PSD. [ABSTRACT FROM AUTHOR]

Aim: Diabetic polyneuropathy is the most described complication in patients with diabetes mellitus. A significant percentage of these patients experience disabling neuropathic pain (painful diabetic polyneuropathy). Small nerve fibers are primarily responsible for peripheral nociception, but objectively assessing its function is challenging. The primary objective of this study was to explore the task execution and outcomes of intra-epidermal electrical stimulation technique that combines nociceptive detection thresholds (NDT) and evoked potentials (EPs) in patients with diabetes. We compared the results of diabetic patients, both with and without painful diabetic polyneuropathy, with those of healthy controls to explore potential clinically relevant information. Methods: The NDT-EP method was applied to 38 patients with diabetes (18 with and 20 without chronic painful neuropathy) and 38 age- and sex-matched healthy controls. Individual mean NDTs, psychometric slopes, EP amplitudes, and the effect of the stimuli on EP amplitudes were analyzed and compared between groups using linear regression. Results: The findings revealed significantly lower detection rates, higher NDTs, and lower psychometric slopes in patients with painful diabetic polyneuropathy than in healthy controls. Both patient groups significantly exhibited lower mean EP amplitudes than healthy controls, which were not linked to pulse amplitudes but influenced by stimulus detection. Conclusions: This study showed altered NDT-EP outcomes in patients with painful diabetic polyneuropathy. Whereas the task execution, NDTs, and psychometric slopes may provide valuable insights into small fiber dysfunction, pulse amplitudes seemed not differently encoded in neurophysiological responses to intra-epidermal electrical stimulation near the detection threshold compared to controls. Future studies should investigate whether the altered NDT-EP outcomes could quantify small fiber dysfunction in patients with diabetes mellitus. We recommend further exploration of NDT-EP measures in other patient groups with nociceptive dysfunction.

Objectives: Vestibular migraine is a neurological disorder characterized by the association of vertigo and headache, affecting up to 1% of the population. Among its differential diagnoses is endolymphatic hydrops. The aim of this study was to investigate the role of cervical vestibular-evoked myogenic potential and electrocochleography in the diagnosis of vestibular migraine. Method: Thirteen women with clinical diagnosis of vestibular migraine (mean age 44 years) and 13 healthy volunteers without auditory and/or vestibular complaints matched for sex and age were evaluated by performing hydrops examinations of cervical vestibular-evoked myogenic potential and electrocochleography. Results: The presence of vertigo and headache was reported by all members of the group with vestibular migraine, associated with symptoms such as nausea, photophobia, and phonophobia. Tinnitus was the most frequent auditory complaint. A significant increase in P1 and N1 latencies was observed in the test group. There was no significant difference in the occurrence of asymmetry and decreased amplitude of the cervical vestibular-evoked myogenic potential. Electrocochleography showed an increase in amplitude of the summation potential. The altered SP/AP ratio was double in the group with vestibular migration, without statistical significance. Conclusions: Changes in latency increase of cervical vestibular-evoked myogenic potential suggests a central lesion. Patients with vestibular migraine may present electrocochleography compatible with endolymphatic hydrops. Level of evidence: Level 4.

Abstract Experiments measuring evoked potentials require flexible and rapid adjustment of stimulation and recording parameters. In this study, we have developed a recording system and an associated Android application that allow making such adjustments wirelessly. The system consists of 3 units: for stimulation, recording and control. Most of the modules in this system are custom made, although the stimulator and tablet are off-the-shelf products. When installed on the tablet, our Android application allows wireless communication with the control unit from a distance of 5 m. In testing, the recording unit had low internal noise and displayed signals faithfully. Upon receiving commands from the control unit, the stimulation unit produced precisely timed pulse outputs. Using this system, we were able to record evoked field potentials in the dentate gyrus of a rat; responses increased as expected with increasing stimulation pulse amplitude and duration.

Experiments measuring evoked potentials require flexible and rapid adjustment of stimulation and recording parameters. In this study, we have developed a recording system and an associated Android application that allow making such adjustments wirelessly. The system consists of 3 units: for stimulation, recording and control. Most of the modules in this system are custom made, although the stimulator and tablet are off-the-shelf products. When installed on the tablet, our Android application allows wireless communication with the control unit from a distance of 5 m. In testing, the recording unit had low internal noise and displayed signals faithfully. Upon receiving commands from the control unit, the stimulation unit produced precisely timed pulse outputs. Using this system, we were able to record evoked field potentials in the dentate gyrus of a rat; responses increased as expected with increasing stimulation pulse amplitude and duration. [ABSTRACT FROM AUTHOR]

INTRODUCTION: Benzodiazepines (BDZs) are commonly used to treat the symptoms of movement disorders; however, deep brain stimulation (DBS) has become a popular treatment for these disorders. Previous studies have investigated the effects of BDZ on cortical activity, no data are currently available on their effects on deep brain regions, nor on these regions responses to DBS. How the BDZ affects the thalamus and basal ganglia in dystonia patients remains unknown. METHODS: DBS recordings were performed in ventral oralis anterior/posterior (VoaVop), ventral intermediate (VIM) and ventral anterior (VA) thalamic subnuclei, as well as globus pallidus interna (GPi) and subthalamic nucleus (STN). Evoked potentials (EP) and frequency domain analysis were performed to determine the BDZ effect on neural activities compared to the control condition (off-BDZ). Three male pediatric patients with dystonia treated with BDZ and undergoing depth electrode evaluation for clinical targeting were recruited for the study. Stimulation was administered at 25 and 55 Hz frequencies and recordings were simultaneously gathered through pairs of externalized stereoelectroencephalography (sEEG) electrodes. EP amplitude and the effect of stimulation on the frequency spectrum of activity were compared at baseline and following clinical administration of BDZ. RESULTS: Frequency analysis showed consistent reductions in activity during BDZ treatment in all studied brain regions for all patients. Evoked potential (EP) analysis showed increased subthalamic nucleus (STN) EP amplitude and decreased ventral intermediate (VIM) and STN EP amplitude during BDZ treatment. INTERPRETATION: BDZs reduce thalamic and basal ganglia activity in multiple regions and alter the efficacy of transmission between these regions. While the mechanism is unknown our results confirm the known widespread effects of this class of medications and identify specific areas within the motor system that are directly affected.

Background: Auditory brainstem response (ABR) to the level-specific (LS) CE-Chirp has been reported to provide optimum neural synchrony along cochlear partitions, theoretically improving ABR waveform resolution. Despite this promising finding, limited studies have been conducted to contrast the results between LS CE-Chirp and Click stimuli. The current study aimed to compare the results of ABR between the two stimuli (Click and LS CE-Chirp). Method: Sixty-seven normal-hearing infants, both with and without risk factors, aged less than 7 months old, participated in this study. The ABR test was conducted at 70 dBnHL using 33.3 stimulus repetition rates with both Click and LS CE-Chirp stimuli. The signal averaging was stopped at a maximum fixed signal average of 2,500 sweeps. Data were statistically compared between the two stimuli using the Wilcoxon signed-rank test. Results: The waves I and V ABRs elicited by LS CE-Chirp exhibited significantly larger amplitudes than the Click stimulus. However, the amplitude of wave III and absolute latencies were similar in both stimuli at a supra-threshold level. Conclusion: LS CE-Chirp has the advantage of larger amplitudes than the ABR from Click at the supra-threshold level (70 dBnHL) in normal-hearing infants. [ABSTRACT FROM AUTHOR]

Background and Objective The precise pathophysiology of cognitive impedance and mental illness in obstructive sleep apnea (OSA) patients remains elusive. Therefore, there is a need for studies on novel diagnoses and therapeutic strategies for cognitive impairment in OSA patients. This work aimed to evaluate cerebral hypoxemia, its consequences on brain metabolism, and local and systemic inflammation, and their subsequent impact on cognitive and psychological functioning. Methods This cross-sectional case-control study was conducted on 30 eligible OSA patients and 20 age/sex-matched healthy controls. All the participants underwent one-night polysomnography, and cognitive evaluation was done using the Mini-Mental State Examination, Montreal Cognitive Assessment, Brief Kingston Standardized Cognitive Assessment, D2 Test of Consideration (to evaluate attention problems), and Wisconsin card sorting test. The psychiatric assessment included the Arabic form of the Hamilton Depression Rating Scale and Beck Depression Inventory-II. A radiology assessment was done using proton magnetic resonance spectroscopy. Neurophysiological assessment was done using the potential cortical (N20) latency and amplitude of somatosensory evoked potential. Laboratory examinations included serum levels of NF-κB, HMGB1, and HIF-1α. Results Polysomnography demonstrated noteworthy increase in the apnea-hypopnea index, respiratory disturbance index, arousal index, snoring index, and wake after sleep onset. It also showed diminished sleep efficiency, total sleep time, and SaO2 nadir in the OSA group. Neuropsychological scales demonstrated poor performance in global cognitive tests, particular cognitive domains impedance, and depression in the OSA group, with noteworthy differences within the group. Magnetic resonance spectroscopy highlighted that OSA patients had a noteworthy bilateral decrement in N-acetylaspartate (NAA) peak, creatine peak, and NAA/choline proportion and an increment in choline peak, lipid peak, lactate peak, choline/creatine proportion, and NAA/creatine proportion in the frontal white matter, hippocampus, and parieto-occipital cortex. Moreover. OSA patients had either missing or decreased amplitude and delayed latency of N20. There was a noteworthy rise of serum inflammatory marker NF-κB, HMGB1, and oxidative stress marker HIF-1α in OSA patients. Conclusions Chronic intermittent hypoxia with resulting amplified inflammatory and oxidative stress in OSA patients may affect brain metabolism; consequently, leading to cognitive and psychological dysfunctions.

Abstract Background Major depressive disorder (MDD) is a prevalent mental health condition affecting millions worldwide, leading to disability and reduced quality of life. MDD poses a global health priority due to its early onset and association with other disabling conditions. Available treatments for MDD exhibit varying effectiveness, and a substantial portion of individuals remain resistant to treatment. Repetitive transcranial magnetic stimulation (rTMS), applied to the left and/or right dorsolateral prefrontal cortex (DLPFC), is an alternative treatment strategy for those experiencing treatment-resistant MDD. The objective of this study is to investigate whether this newer form of rTMS, namely theta burst stimulation (TBS), when performed unilaterally or bilaterally, is efficacious in treatment-resistant MDD. Methods In this naturalistic, randomized double-blinded non-inferiority trial, participants with a major depressive episode will be randomized to receive either unilateral (i.e., continuous TBS [cTBS] to the right and sham TBS to the left DLPFC) or bilateral sequential TBS (i.e., cTBS to the right and intermittent TBS [iTBS] to the left DLPFC) delivered 5 days a week for 4–6 weeks. Responders will move onto a 6-month flexible maintenance phase where TBS treatment will be delivered at a decreasing frequency depending on degree of symptom mitigation. Several clinical assessments and neuroimaging and neurophysiological biomarkers will be collected to investigate treatment response and potential associated biomarkers. A non-inferiority analysis will investigate whether bilateral sequential TBS is non-inferior to unilateral TBS and regression analyses will investigate biomarkers of treatment response. We expect to recruit a maximal of 256 participants. This trial is approved by the Research Ethics Board of The Royal's Institute of Mental Health Research (REB# 2,019,071) and will follow the Declaration of Helsinki. Findings will be published in peer-reviewed journals. Discussion Comprehensive assessment of symptoms and neurophysiological biomarkers will contribute to understanding the differential efficacy of the tested treatment protocols, identifying biomarkers for treatment response, and shedding light into underlying mechanisms of TBS. Our findings will inform future clinical trials and aid in personalizing treatment selection and scheduling for individuals with MDD. Trial registration The trial is registered on https://clinicaltrials.gov/ct2/home (#NCT04142996).

A significant portion of hearing-impaired children have additional disabilities, but data about the maturation of their auditory cortex are scarce. In these children, behavioral tests are often unreliable, and objective tests are needed for diagnostics and follow-up. This study aimed to explore auditory cortical maturation and language development, and the usability of an objective electroencephalogram-based biomarker in children with multiple disabilities. In 65 hearing aid and cochlear implant users (36 females; 36 with multiple disabilities; 44.3 ± 18.5 months of age, mean ± SD), auditory processing was examined using the P1 cortical auditory evoked response biomarker, and language development with the Preschool Language Scales 5th edition (PLS-5). During the study, all of the children received intensive extra language therapy for six months. No significant differences were found between the groups in P1 latency development, the proportion of abnormal P1 latencies, or the number of children whose P1 latencies changed from abnormal to normal during the study. The PLS-5 total language scores, auditory comprehension scores, or expressive communication scores did not differ between groups either. The P1 latencies showed meaningful negative correlations with the language scores. The results suggest that auditory cortex development is similar in hearing-impaired children with/without additional disabilities, and the P1 biomarker is a feasible tool to evaluate central auditory maturation in children with multiple disabilities. [ABSTRACT FROM AUTHOR]

Background: Major depressive disorder (MDD) is a prevalent mental health condition affecting millions worldwide, leading to disability and reduced quality of life. MDD poses a global health priority due to its early onset and association with other disabling conditions. Available treatments for MDD exhibit varying effectiveness, and a substantial portion of individuals remain resistant to treatment. Repetitive transcranial magnetic stimulation (rTMS), applied to the left and/or right dorsolateral prefrontal cortex (DLPFC), is an alternative treatment strategy for those experiencing treatment-resistant MDD. The objective of this study is to investigate whether this newer form of rTMS, namely theta burst stimulation (TBS), when performed unilaterally or bilaterally, is efficacious in treatment-resistant MDD. Methods: In this naturalistic, randomized double-blinded non-inferiority trial, participants with a major depressive episode will be randomized to receive either unilateral (i.e., continuous TBS [cTBS] to the right and sham TBS to the left DLPFC) or bilateral sequential TBS (i.e., cTBS to the right and intermittent TBS [iTBS] to the left DLPFC) delivered 5 days a week for 4–6 weeks. Responders will move onto a 6-month flexible maintenance phase where TBS treatment will be delivered at a decreasing frequency depending on degree of symptom mitigation. Several clinical assessments and neuroimaging and neurophysiological biomarkers will be collected to investigate treatment response and potential associated biomarkers. A non-inferiority analysis will investigate whether bilateral sequential TBS is non-inferior to unilateral TBS and regression analyses will investigate biomarkers of treatment response. We expect to recruit a maximal of 256 participants. This trial is approved by the Research Ethics Board of The Royal's Institute of Mental Health Research (REB# 2,019,071) and will follow the Declaration of Helsinki. Findings will be published in peer-reviewed journals. Discussion: Comprehensive assessment of symptoms and neurophysiological biomarkers will contribute to understanding the differential efficacy of the tested treatment protocols, identifying biomarkers for treatment response, and shedding light into underlying mechanisms of TBS. Our findings will inform future clinical trials and aid in personalizing treatment selection and scheduling for individuals with MDD. Trial registration: The trial is registered on https://clinicaltrials.gov/ct2/home (#NCT04142996). [ABSTRACT FROM AUTHOR]

[Display omitted] • Behavioural audiovisual improvements are reflected by enhanced activation in temporal and occipital regions at P2 latency. • Background noise delays responses within the auditory cortex (N1) and reduces superior frontal cortex activity (P2). • Noise reduction via ForwardFocus improves audiovisual speech performance by allowing the reallocation of attentional resources. Hearing with a cochlear implant (CI) is difficult in noisy environments, but the use of noise reduction algorithms, specifically ForwardFocus, can improve speech intelligibility. The current event-related potentials (ERP) study examined the electrophysiological correlates of this perceptual improvement. Ten bimodal CI users performed a syllable-identification task in auditory and audiovisual conditions, with syllables presented from the front and stationary noise presented from the sides. Brainstorm was used for spatio-temporal evaluation of ERPs. CI users revealed an audiovisual benefit as reflected by shorter response times and greater activation in temporal and occipital regions at P2 latency. However, in auditory and audiovisual conditions, background noise hampered speech processing, leading to longer response times and delayed auditory-cortex-activation at N1 latency. Nevertheless, activating ForwardFocus resulted in shorter response times, reduced listening effort and enhanced superior-frontal-cortex-activation at P2 latency, particularly in audiovisual conditions. ForwardFocus enhances speech intelligibility in audiovisual speech conditions by potentially allowing the reallocation of attentional resources to relevant auditory speech cues. This study shows for CI users that background noise and ForwardFocus differentially affect spatio-temporal cortical response patterns, both in auditory and audiovisual speech conditions. [ABSTRACT FROM AUTHOR]

Animal research has extensively shown that inflammation plays a pivotal role in the development of the nociceptive system. The recent article by Cobo et al. [10] constitutes a first look into the acute effects of a neonatal inflammation episode on pain sensitivity in human neonates. In response to a noxious and tactile stimulus, neonates with early-onset infection had greater spinal cord excitability and cortical brain activity than those in the control group, hinting at an altered nociceptive sensitivity. These results shed light on the implications of neonatal infection episodes, antibiotic treatments, inflammatory factors, and microbiome-host interactions in the development of the nociceptive system. They also uncover methodological shortcomings in our evaluation and understanding of pain in neonates. [ABSTRACT FROM AUTHOR]

Transcranial magnetic stimulation (TMS) with electroencephalography (EEG), that is TMS‐EEG, may assist in managing epilepsy. We systematically reviewed the quality of reporting and findings in TMS‐EEG studies on people with epilepsy and healthy controls, and on healthy individuals taking anti‐seizure medication. We searched the Cochrane Library, Embase, PubMed and Web of Science databases for original TMS‐EEG studies comparing people with epilepsy and healthy controls, and healthy subjects before and after taking anti‐seizure medication. Studies should involve quantitative analyses of TMS‐evoked EEG responses. We evaluated the reporting of study population characteristics and TMS‐EEG protocols (TMS sessions and equipment, TMS trials and EEG protocol), assessed the variation between protocols, and recorded the main TMS‐EEG findings. We identified 20 articles reporting 14 unique study populations and TMS methodologies. The median reporting rate for the group of people with epilepsy parameters was 3.5/7 studies and for the TMS parameters was 13/14 studies. TMS protocols varied between studies. Fifteen out of 28 anti‐seizure medication trials in total were evaluated with time‐domain analyses of single‐pulse TMS‐EEG data. Anti‐seizure medication significantly increased N45, and decreased N100 and P180 component amplitudes but in marginal numbers (N45: 8/15, N100: 7/15, P180: 6/15). Eight articles compared people with epilepsy and controls using different analyses, thus limiting comparability. The reporting quality and methodological uniformity between studies evaluating TMS‐EEG as an epilepsy biomarker is poor. The inconsistent findings question the validity of TMS‐EEG as an epilepsy biomarker. To demonstrate TMS‐EEG clinical applicability, methodology and reporting standards are required. [ABSTRACT FROM AUTHOR]

The scientific advances of recent years have made available to anyone affordable hardware devices capable of doing something unthinkable until a few years ago, the reading of brain waves. It means that through small wearable devices it is possible to perform an electroencephalography (EEG), albeit with less potential than those offered by high-cost professional devices. Such devices make it possible for researchers a huge number of experiments that were once impossible in many areas due to the high costs of the necessary hardware. Many studies in the literature explore the use of EEG data as a biometric approach for people identification, but, unfortunately, it presents problems mainly related to the difficulty of extracting unique and stable patterns from users, despite the adoption of sophisticated techniques. An approach to face this problem is based on the evoked potentials (EPs), external stimuli applied during the EEG reading, a noninvasive technique used for many years in clinical routine, in combination with other diagnostic tests, to evaluate the electrical activity related to some areas of the brain and spinal cord to diagnose neurological disorders. In consideration of the growing number of works in the literature that combine the EEG and EP approaches for biometric purposes, this work aims to evaluate the practical feasibility of such approaches as reliable biometric instruments for user identification by surveying the state of the art of the last 6 years, also providing an overview of the elements and concepts related to this research area. [ABSTRACT FROM AUTHOR]

Decerebrated animals are often used in experimental neurophysiology to study multilevel physiological processes. The model of a decerebrated cat is traditionally used to study locomotion in acute experiments. We wondered if it would be possible to replace it with electrical epidural stimulation of the spinal cord with a decerebrated rat model. On an acute preparation of 16 Wistar rats decerebrated at the precollicular level, the tonic muscles activity, muscles evoked potentials and the possibility of inducing locomotion during electrical epidural stimulation of the spinal cord, were studied. Histological control of the level of decerebration was performed in 10 rats. Quadrupedal walking was induced in five animals, bipedal hindlimb walking—in one animal; the parameters of the evoked locomotion do not depend on the substantia nigra degree of damage. The tonic activity and the amplitude of the sensory component of the evoked potential of the hindlimb muscles (mm. tibialis anterior and gastrocnemius medialis) depend on the rostrocaudal level of decerebration—they are higher when the substantia nigra is damaged. Thus, the model under consideration makes it possible to successfully study muscle tonic activity and evoked muscle potentials; however, the use of this model in the study of controlled locomotion requires additional research. [ABSTRACT FROM AUTHOR]

The phenomenon of plasticity in the striatum, and its relation with the striatum-nigra neuronal circuit has clinical and neurophysiological relevance to Parkinson and epilepsy. High frequency stimulation (HFS) can induce neural plasticity. Furthermore, it is possible to induce plasticity in the dorsal striatum and this can be modulated by substantia nigra activity. But it has not been shown yet what would be the effects in the striatum-nigra circuit after plasticity induction in striatum with HSF. Literature also misses a detailed description of the way back loop of the circuit: the striatal firing rate after substantia nigrás inhibition. We here conducted: First Experiment, application of HFS in dorsomedial striatum and measure of spontaneous and longlasting behavior expression in the open field three days later; Second, application of single pulses on dorsomedial striatum and measure of the evoked potentials in substantia nigra before and after HFS; Third Experiment: inhibition of substantia nigra and recording of the firing rate of dorsomedial striatum. HFS in dorsomedial striatum caused increased locomotion behaviors, but not classical stereotypy. However, rats had either an increase or decrease in substantia nigrás evoked potentials. Also, substantia nigrás inhibition caused an increase in dorsomedial striatum firing rate. Present data are suggestive of a potential application of HFS in striatum, as an attempt to modulate behavior rigidity and hypokinesia of diseases involving the basal ganglia, especially Parkinson´s Disease. [ABSTRACT FROM AUTHOR]

IntroductionBenzodiazepines (BDZs) are commonly used to treat the symptoms of movement disorders; however, deep brain stimulation (DBS) has become a popular treatment for these disorders. Previous studies have investigated the effects of BDZ on cortical activity, no data are currently available on their effects on deep brain regions, nor on these regions’ responses to DBS. How the BDZ affects the thalamus and basal ganglia in dystonia patients remains unknown.MethodsDBS recordings were performed in ventral oralis anterior/posterior (VoaVop), ventral intermediate (VIM) and ventral anterior (VA) thalamic subnuclei, as well as globus pallidus interna (GPi) and subthalamic nucleus (STN). Evoked potentials (EP) and frequency domain analysis were performed to determine the BDZ effect on neural activities compared to the control condition (off-BDZ). Three male pediatric patients with dystonia treated with BDZ and undergoing depth electrode evaluation for clinical targeting were recruited for the study. Stimulation was administered at 25 and 55 Hz frequencies and recordings were simultaneously gathered through pairs of externalized stereoelectroencephalography (sEEG) electrodes. EP amplitude and the effect of stimulation on the frequency spectrum of activity were compared at baseline and following clinical administration of BDZ.ResultsFrequency analysis showed consistent reductions in activity during BDZ treatment in all studied brain regions for all patients. Evoked potential (EP) analysis showed increased subthalamic nucleus (STN) EP amplitude and decreased ventral intermediate (VIM) and STN EP amplitude during BDZ treatment.InterpretationBDZs reduce thalamic and basal ganglia activity in multiple regions and alter the efficacy of transmission between these regions. While the mechanism is unknown our results confirm the known widespread effects of this class of medications and identify specific areas within the motor system that are directly affected.

Quickly and efficiently extracting evoked potential information from noise is critical to the clinical practice of intraoperative neurophysiologic monitoring (IONM). Currently this is primarily done using trained professionals to interpret averaged waveforms. The purpose of this paper is to evaluate and compare multiple means of electronically extracting simple to understand evoked potential characteristics with minimum averaging. A number of evoked potential models are studied and their performance evaluated as a function of the signal to noise level in simulations. Methods: which extract the least number of parameters from the data are least sensitive to the effects of noise and are easiest to interpret. The simplest model uses the baseline evoked potential and the correlation receiver to provide an amplitude measure. Amplitude measures extracted using the correlation receiver show superior performance to those based on peak to peak amplitude measures. In addition, measures of change in latency or shape of the evoked potential can be extracted using the derivative of the baseline evoked response or other methods. This methodology allows real-time access to amplitude measures that can be understood by the entire OR staff as they are small, dimensionless numbers of order unity which are simple to interpret. The IONM team can then adjust averaging and other parameters to allow for visual interpretation of waveforms as appropriate.

Clinical neurophysiology constructs a wealth of dynamic information pertaining to the integrity and function of both central and peripheral nervous systems. As with many technological fields, there has been an explosion of data in neurophysiology over recent years, and this requires considerable analysis by experts. Computational algorithms and especially advances in machine learning (ML) have the ability to assist with this task and potentially reveal hidden insights. In this update article, we will provide a brief overview where such technology is being applied in clinical neurophysiology and possible future directions. [ABSTRACT FROM AUTHOR]

Objectives: Vestibular migraine is a neurological disorder characterized by the association of vertigo and headache, affecting up to 1% of the population. Among its differential diagnoses is endolymphatic hydrops. The aim of this study was to investigate the role of cervical vestibular-evoked myogenic potential and electrocochleography in the diagnosis of vestibular migraine., Method: Thirteen women with clinical diagnosis of vestibular migraine (mean age 44 years) and 13 healthy volunteers without auditory and/or vestibular complaints matched for sex and age were evaluated by performing hydrops examinations of cervical vestibular-evoked myogenic potential and electrocochleography., Results: The presence of vertigo and headache was reported by all members of the group with vestibular migraine, associated with symptoms such as nausea, photophobia, and phonophobia. Tinnitus was the most frequent auditory complaint. A significant increase in P1 and N1 latencies was observed in the test group. There was no significant difference in the occurrence of asymmetry and decreased amplitude of the cervical vestibular-evoked myogenic potential. Electrocochleography showed an increase in amplitude of the summation potential. The altered SP/AP ratio was double in the group with vestibular migration, without statistical significance., Conclusions: Changes in latency increase of cervical vestibular-evoked myogenic potential suggests a central lesion. Patients with vestibular migraine may present electrocochleography compatible with endolymphatic hydrops., Level of Evidence: Level 4., (Copyright © 2024 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier España S.L.U. All rights reserved.)

Noninvasive electroencephalogram (EEG) in unanesthetized nonhuman primates is useful for basic science and biomedical applications but presents several technical challenges. In particular, multiple EEG electrode application to the scalp of small-sized monkeys, such as common marmosets, has been difficult, if not impossible. Here, we describe a novel approach, using the “dip-in electrode” method, which enables multichannel noninvasive EEG recording in a marmoset through short and small silicone tubes, with an internal diameter of 4 mm. First, the cut face of the tube was glued to the shaved scalp. Then, the tube was filled with the electrode gel, and a small electrode (4 mm in diameter) was dipped into the gel to contact the skin electrically while being electrically isolated from the neighboring channels. The minimum inter-electrode distance was 6 mm, which was limited by the outer diameter of the tubes. A proof of concept was provided through successful 32-channel recording of scalp EEG and topographic mapping of the cortical auditory evoked potentials in an unanesthetized marmoset. This had not been possible with the existing methods using gauze or tape for electrode fixation. Our method provides a feasible means for noninvasive scalp recording of EEG and evoked potentials in marmoset monkeys and possibly other nonhuman primates and non-primate mammals.

Cortico-cortical evoked potentials (CCEPs) are a common tool for probing effective connectivity in intracranial human electrophysiology. As with all human electrophysiology data, CCEP data are highly susceptible to noise. To address noise, filters and re-referencing are often applied to CCEP data, but different processing strategies are used from study to study. We systematically compare how common average re-referencing and filtering CCEP data impacts quantification. We show that common average re-referencing and filters, particularly filters that cut out more frequencies, can significantly impact the quantification of CCEP magnitude and morphology. We identify that high cutoff high pass filters (> 0.5 Hz), low cutoff low pass filters (< 200 Hz), and common average re-referencing impact quantification across subjects. However, we also demonstrate that the presence of noise may impact CCEP quantification, and preprocessing is necessary to mitigate this. We show that filtering is more effective than re-referencing or averaging across trials for reducing most common types of noise. These results suggest that existing CCEP processing methods must be applied with care to maximize noise reduction and minimize changes to the data. We do not test every available processing strategy; rather we demonstrate that processing can influence the results of CCEP studies. We emphasize the importance of reporting all processing methods, particularly re-referencing methods. We propose a general framework for choosing an appropriate processing pipeline for CCEP data, taking into consideration the noise levels of a specific dataset. We suggest that minimal gentle filtering is preferable. • CCEP processing strategies vary widely across the literature. • Processing can significantly impact the results of CCEP quantification. • The amount of noise in data should be considered when choosing processing methods. • It is critical that studies reporting CCEP results document signal processing steps. [ABSTRACT FROM AUTHOR]

Introduction. Aerobic exercise interventions may affect different cognitive domains such as attention, working memory, inhibition, etc. However, the neural mechanisms underlying this relationship, remains uncertain. Objective. To perform a systematic review on exercise intervention studies that use event-related potentials (ERPs) as outcome for cognitive performance. Methods. We identified studies through searches in four databases reporting the effects of either an acute bout or chronic exercise on any ERP associated with cognitive performance. Study population included participants >17 years of age with or without a diagnosis. Results. A total of 5,797 records were initially identified through database searching of which 52 were eligible for inclusion. Most studies were of acute aerobic exercise with moderate intensity. Results were heterogenious across studies, but there was a trend that ERP amplitude increased and (to a lesser extent) latencies decreased postexercise. The P3 ERP was the most often reported ERP. Conclusion. Heterogeneity across studies regarding methodology limited the possibility to draw definitive conclusions but the most consistent findings were that acute aerobic exercise was associated with higher amplitudes, and to a lesser extent shorter latencies, of ERPs. [ABSTRACT FROM AUTHOR]

• Evoked magnetic fields of the ulnar nerve at the elbow were recorded by magnetoneurography. • The neural activity of the ulnar nerve was visualized as reconstructed currents. • Magnetoneurography is a novel functional imaging technique for the ulnar nerve. To visualize the neural activity of the ulnar nerve at the elbow using magnetoneurography (MNG). Subjects were asymptomatic volunteers (eight men and one woman; age, 26–53 years) and a male patient with cubital tunnel syndrome (age, 54 years). The ulnar nerve was electrically stimulated at the left wrist and evoked magnetic fields were recorded by a 132-channel biomagnetometer system with a superconducting quantum interference device at the elbow. Evoked potentials were also recorded and their correspondence to the evoked magnetic fields was evaluated in healthy participants. Evoked magnetic fields were successfully recorded by MNG, and computationally reconstructed currents were able to visualize the neural activity of the ulnar nerve at the elbow. In the affected arm of the patient, reconstructed intra-axonal and inflow currents attenuated and decelerated around the elbow. Latencies of reconstructed currents and evoked potentials were correspondent within an error of 0.4 ms in asymptomatic participants. Neural activity in the ulnar nerve can be visualized by MNG, which may be a novel functional imaging technique for ulnar neuropathy at the elbow, including cubital tunnel syndrome. MNG permits visualization of evoked currents in the ulnar nerve at the cubital tunnel. [ABSTRACT FROM AUTHOR]

Introduction: Entrapment of the lateral femoral cutaneous nerve (LFCN) of thigh results in meralgia paresthetica (MP). Standard electrophysiological tests for MP are technically demanding and unreliable. We aimed to study the role of pain-related evoked potentials (PREP) in the diagnosis of MP. Methods: Patients with MP and normal volunteers were included. PREP was recorded by stimulating the skin over the lateral thigh 20 cm below the anterior-superior iliac spine and recording from the cortex at Cz. Results: A total of 28 subjects and 56 LFCNs were studied. 36 nerves had MP and 20 were normal. The mean PREP latency was 118 (8) ms among normal controls and 164 (10.8) ms in MP. The optimal cut-off point for the diagnosis of MP was 134 ms. Area under receiver operator characteristic curve was 0.97; sensitivity was 91.7% and specificity was 100%. Conclusion: PREP is reliable and easy to use electrophysiological test in establishing the diagnosis of MP.

Objective: Hemifacial atrophy (HFA) is a rare disorder characterized by progressive unilateral wasting facial soft tissue, muscle, and/or bone. Trigeminal nerve abnormalities may contribute to or result from disease pathophysiology. We aimed to gain further insights into the role of trigeminal pathophysiology along the HFA severity spectrum. Methods: A systematic literature review was performed according to PRISMA standards. Retrospective cases of HFA from the literature and Mayo Clinic EMG database were pooled for descriptive and semi-quantitative analysis. Results: Overall, 13 total HFA patients were identified through literature and database reviews. Trigeminal nerve testing was abnormal in 9/13 (69%), exclusively in moderate-severe cases. Abnormalities suggested a peripheral (7/9, 78%) or mixed central/peripheral (2/9, 22%) localization. Trigeminal nerve abnormalities were not identified in any of the 4 cases with mild disease severity. Conclusion: Moderate to severe cases of HFA were associated with electrophysiological trigeminal abnormalities. No abnormalities were seen in mild cases of HFA. Significance: Trigeminal nerve electrophysiology may serve as a biomarker of moderate-severe disease progression, likely reflecting the consequences of progressive soft tissue atrophy.

Background: Coma after acute brain structural injury (ABI) are associated with high mortality and disability. Somatosensory evoked potentials (SSEP) N20 and N70 are used to predict prognosis. Purpose: We assessed the utility of SSEP (N20-N70) as an early indicator of long-term functional prognosis in these patients. Methods: We conducted a retrospective cohort study of patients admitted to the intensive care unit (ICU) with a diagnosis of coma after ABI (n=60). An SSEP study including N20 and N70 was performed 24–72 hours after coma onset. Functional recovery was evaluated 6 to 12 months later using the Modified Glasgow Scale (mGS). The study was approved by our local research ethics committee. Results: The absence of N20 (41% specificity=100%) or N70 (78%) was a strong indicator of a poor outcome. In contrast, the presence of N70 was an indicator of a good outcome (specificity=64.2% sensitivity=91.3%). Conclusion: SSEP N20 and N70 are useful early prognostic markers with high specificity (N20) and sensitivity (N70). N70 has potential additional value for improving the prediction of good functional outcomes in the long term. [ABSTRACT FROM AUTHOR]

Sleep deprivation has been shown to increase pain intensity and decrease pain thresholds in healthy subjects. In chronic pain patients, sleep impairment often worsens the perceived pain intensity. This increased pain perception is the result of altered nociceptive processing. We recently developed a method to quantify and monitor altered nociceptive processing by simultaneous tracking of psychophysical detection thresholds and recording of evoked cortical potentials during intra-epidermal electric stimulation. In this study, we assessed the sensitivity of nociceptive detection thresholds and evoked potentials to altered nociceptive processing after sleep deprivation in an exploratory study with 24 healthy male and 24 healthy female subjects. In each subject, we tracked nociceptive detection thresholds and recorded central evoked potentials in response to 180 single- and 180 double-pulse intra-epidermal electric stimuli. Results showed that the detection thresholds for single- and double-pulse stimuli and the average central evoked potential for single-pulse stimuli were significantly decreased after sleep deprivation. When analyzed separated by sex, these effects were only significant in the male population. Multivariate analysis showed that the decrease of central evoked potential was associated with a decrease of task-related evoked activity. Measurement repetition led to a decrease of the detection threshold to double-pulse stimuli in the mixed and the female population, but did not significantly affect any other outcome measures. These results suggest that simultaneous tracking of psychophysical detection thresholds and evoked potentials is a useful method to observe altered nociceptive processing after sleep deprivation, but is also sensitive to sex differences and measurement repetition. [ABSTRACT FROM AUTHOR]

Beta-thalassemia is a genetico-haematological disorder that affects the integrity, structure, and survival of red blood cells due to deleterious mutation in the β-globulin chain of hemoglobin. Other than blood disorder, this condition gives rise to numerous neurological and haematophysiological conditions which have not been fully discussed yet. These conditions include extramedullary hematopoiesis, evoked potential (Sensory, Auditory and Visual), neuropathy and myopathy and predisposition to the hypercoagulable state leading to stroke. Moreover, most opted therapy to alleviate this condition intrigue neurotoxicity that requires clinician's round the clock attention. Beta thalassemia remains an incurable disease, and various therapies have been introduced to fulfill the body's blood requirement. But this condition implicitly gives rise to a damaging range of symptoms that cannot be overlooked. Therefore, our review encompasses all those anomalies associated with beta-thalassemia and its probable curative therapy. Keywords: Beta thalassemia, Neurological deficits, Cognitive impairment, Extramedullary hematopoiesis, Evoked potential, Neuropathy.

In humans, age-related declines in vision, hearing, and touch coincide with changes in amplitude and latency of sensory-evoked potentials. These age-related differences in neural activity may be related to a common deterioration of supra-modal brain areas (e.g., PFC) that mediate activity in sensory cortices or reflect specific sensorineural impairments that may differ between sensory modalities. To distinguish between these two possibilities, we measured neuroelectric brain activity while 37 young adults (18-30 years, 18 males) and 35 older adults (60-88 years, 20 males) were presented with a rapid randomized sequence of lateralized auditory, visual, and somatosensory stimuli. Within each sensory domain, we compared amplitudes and latencies of sensory-evoked responses, source activity, and functional connectivity (via phase-locking value) between groups. We found that older adults' early sensory-evoked responses were greater in amplitude than those of young adults in all three modalities, which coincided with enhanced source activity in auditory, visual, and somatosensory cortices. Older adults also showed stronger neural synchrony than young adults between superior prefrontal and sensory cortices; and in older adults, the degree of phase synchrony was positively correlated with the magnitude of source activity in sensory areas. Critically, older adults who showed enhanced neural activity in one sensory domain also showed enhanced activity in other modalities. Together, these findings support the common cause hypothesis of aging and highlight the role of prefrontal regions in exerting top-down control over sensory cortices. [ABSTRACT FROM AUTHOR]

• This review is the second in the series of articles on the use of clinical neurophysiology for the study of movement disorders. • It focuses on the most useful non-invasive methods and techniques that can probe the neurophysiology of the central nervous system in humans. • Tools include reflex studies, transcranial brain stimulation, electroencephalography and reaction times. This is the second chapter of the series on the use of clinical neurophysiology for the study of movement disorders. It focusses on methods that can be used to probe neural circuits in brain and spinal cord. These include use of spinal and supraspinal reflexes to probe the integrity of transmission in specific pathways; transcranial methods of brain stimulation such as transcranial magnetic stimulation and transcranial direct current stimulation, which activate or modulate (respectively) the activity of populations of central neurones; EEG methods, both in conjunction with brain stimulation or with behavioural measures that record the activity of populations of central neurones; and pure behavioural measures that allow us to build conceptual models of motor control. The methods are discussed mainly in relation to work on healthy individuals. Later chapters will focus specifically on changes caused by pathology. [ABSTRACT FROM AUTHOR]

Introduction: Insect cyborg is a kind of novel robot based on insect–machine interface and principles of neurobiology. The key idea is to stimulate live insects by specific stimuli; thus, the flight trajectory of insects could be controlled as anticipated. However, the neuroregulatory mechanism of insect flight has not been elucidated completely at present. Methods: To explore the neuro‐mechanism of insect flight behaviors, a series of electrical stimulation was applied on the optic lobes of semi‐constrained honeybees. Times of flight initiation, flapping frequency, and duration were recorded by a high‐speed camera. In addition, flapping and steering initiation experiments of the cyborg honeybee were verified. Moreover, series of local field potential signals of optic lobes during flapping were collected, pre‐processed to remove baseline wander and DC components, then analyzed by power spectrum estimation. Results: A quantitative optimization method and optimal stimulation parameters of flight initiation were presented. Stimulation results showed that the flapping duration differed greatly while the flapping frequency varied with little difference among different individuals. Moreover, there was always a fluctuation peak around 20–30 Hz in power spectral density (PSD) curves during flapping, distinguishing from calm state, which indicated some brain activity changes during flapping. Conclusions: Our study presented a range of relatively optimal electrical parameters to initiate honeybee flight behavior. Meanwhile, the regularity of flapping duration and flapping frequency under electrical stimulations with different parameters were given. The feasibility of controlling a honeybee's flight behavior by brain electrical stimulation was verified through the flapping and steering initiation experiment of honeybees under semi‐constrained state. PSD fluctuations reflected changes in brain activity during flapping and that those fluctuation characteristics at the specific frequency band could be sensitive determinants to distinguish whether the honeybee was flying or not, which benefits our understanding of honeybee's flapping behavior and furthers the study of honeybee cyborgs. [ABSTRACT FROM AUTHOR]

Background: Electrical auricular vagus nerve stimulation (taVNS) is an emerging therapy. Stimuli are transported to brainstem nuclei, whereby its multiple projections reach to many subcortical and cortical areas, thus allowing the neuromodulation of several systemic physiological processes. We aim to define the best auricular target for taVNS through vagus somatosensory evoked potential (VSEP) elicited stimulating different auricular areas with different electrode sizes. Methods: Twenty‐six subjects were enrolled. Three stimulation areas were studied: simultaneous cymba and cavum (CC), cymba (C) and earlobe (L); and two electrode sizes: extra‐large (X) and small (S). We studied the effect of five combinations (CCX, CCS, CS, LX and LS) on VSEP´s latency and amplitude, and sensory and pain threshold (Pt) using a lineal mixed model regression analysis. We used CS combination, used in a commercial device, as reference model. Results: Valid VSEP were obtained for CCX, CCS and CS but not in LX and LS. Both CCS and CCX tests showed significant amplitude increases. The same effect was observed in CCX using CCS as reference. Significant increases in Pt were found for CCX and LX. The same effect was observed in CCX using LX as reference. Conclusion: The results suggest that CC and C areas are active targets for taVNS but not for earlobe, as anatomical data support. Considering that amplitude reflects the synchronized electrical activity generated, we conclude the most effective topography is the simultaneous stimulation of cymba and concha. The use of X‐sized electrodes increases the amplitudes and makes the stimulation more comfortable. [ABSTRACT FROM AUTHOR]

Abstract Introduction Insect cyborg is a kind of novel robot based on insect–machine interface and principles of neurobiology. The key idea is to stimulate live insects by specific stimuli; thus, the flight trajectory of insects could be controlled as anticipated. However, the neuroregulatory mechanism of insect flight has not been elucidated completely at present. Methods To explore the neuro‐mechanism of insect flight behaviors, a series of electrical stimulation was applied on the optic lobes of semi‐constrained honeybees. Times of flight initiation, flapping frequency, and duration were recorded by a high‐speed camera. In addition, flapping and steering initiation experiments of the cyborg honeybee were verified. Moreover, series of local field potential signals of optic lobes during flapping were collected, pre‐processed to remove baseline wander and DC components, then analyzed by power spectrum estimation. Results A quantitative optimization method and optimal stimulation parameters of flight initiation were presented. Stimulation results showed that the flapping duration differed greatly while the flapping frequency varied with little difference among different individuals. Moreover, there was always a fluctuation peak around 20–30 Hz in power spectral density (PSD) curves during flapping, distinguishing from calm state, which indicated some brain activity changes during flapping. Conclusions Our study presented a range of relatively optimal electrical parameters to initiate honeybee flight behavior. Meanwhile, the regularity of flapping duration and flapping frequency under electrical stimulations with different parameters were given. The feasibility of controlling a honeybee's flight behavior by brain electrical stimulation was verified through the flapping and steering initiation experiment of honeybees under semi‐constrained state. PSD fluctuations reflected changes in brain activity during flapping and that those fluctuation characteristics at the specific frequency band could be sensitive determinants to distinguish whether the honeybee was flying or not, which benefits our understanding of honeybee's flapping behavior and furthers the study of honeybee cyborgs.

Synchronization of neuronal responses over large distances is hypothesized to be important for many cortical functions. However, no straightforward methods exist to estimate synchrony non-invasively in the living human brain. MEG and EEG measure the whole brain, but the sensors pool over large, overlapping cortical regions, obscuring the underlying neural synchrony. Here, we developed a model from stimulus to cortex to MEG sensors to disentangle neural synchrony from spatial pooling of the instrument. We find that synchrony across cortex has a surprisingly large and systematic effect on predicted MEG spatial topography. We then conducted visual MEG experiments and separated responses into stimulus-locked and broadband components. The stimulus-locked topography was similar to model predictions assuming synchronous neural sources, whereas the broadband topography was similar to model predictions assuming asynchronous sources. We infer that visual stimulation elicits two distinct types of neural responses, one highly synchronous and one largely asynchronous across cortex.

Abstract Background Electrical auricular vagus nerve stimulation (taVNS) is an emerging therapy. Stimuli are transported to brainstem nuclei, whereby its multiple projections reach to many subcortical and cortical areas, thus allowing the neuromodulation of several systemic physiological processes. We aim to define the best auricular target for taVNS through vagus somatosensory evoked potential (VSEP) elicited stimulating different auricular areas with different electrode sizes. Methods Twenty‐six subjects were enrolled. Three stimulation areas were studied: simultaneous cymba and cavum (CC), cymba (C) and earlobe (L); and two electrode sizes: extra‐large (X) and small (S). We studied the effect of five combinations (CCX, CCS, CS, LX and LS) on VSEP´s latency and amplitude, and sensory and pain threshold (Pt) using a lineal mixed model regression analysis. We used CS combination, used in a commercial device, as reference model. Results Valid VSEP were obtained for CCX, CCS and CS but not in LX and LS. Both CCS and CCX tests showed significant amplitude increases. The same effect was observed in CCX using CCS as reference. Significant increases in Pt were found for CCX and LX. The same effect was observed in CCX using LX as reference. Conclusion The results suggest that CC and C areas are active targets for taVNS but not for earlobe, as anatomical data support. Considering that amplitude reflects the synchronized electrical activity generated, we conclude the most effective topography is the simultaneous stimulation of cymba and concha. The use of X‐sized electrodes increases the amplitudes and makes the stimulation more comfortable.

Human spatial memory research has significantly progressed since the development of computerized tasks, with many studies examining sex-related performances. However, few studies explore the underlying electrophysiological correlates according to sex. In this study event-related potentials were compared between male and female participants during the performance of an allocentric spatial recognition task. Twenty-nine university students took part in the research. Results showed that while general performance was similar in both sexes, the brain of males and females displayed a differential activation. Males showed increased N200 modulation than females in the three phases of memory process (encoding, maintenance, and retrieval). Meanwhile females showed increased activation of P300 in the three phases of memory process compared to males. In addition, females exhibited more negative slow wave (NSW) activity during the encoding phase. These differences are discussed in terms of attentional control and the allocation of attentional resources during spatial processing. Our findings demonstrate that sex modulates the resources recruited to performed this spatial task.