Peak Latency Research Articles

Assessing mismatch negativity (MMN) and P3b within-individual sensitivity - A comparison between the local-global paradigm and two specialized oddball sequences.

Mismatch negativity (MMN) and P3b are well known for their clinical utility. There exists no gold standard, however, for acquiring them as EEG markers of consciousness in clinical settings. This may explain why the within-individual sensitivity of MMN/P3b paradigms is often quite poor and why seemingly identical EEG markers can behave differently across Disorders of consciousness (DoC) studies. Here, we compare two traditional paradigms for MMN or P3b assessment with the recently more popular local-global paradigm that promises to assess MMN and P3b orthogonally within one oddball sequence. All three paradigms were administered to healthy participants (N = 15) with concurrent EEG. A clear MMN and local effect were found for 15/15 participants. The P3b and global effect were found for 14/15 and 13/15 participants, respectively. There were no systematic differences between the global effect and P3b. Indeed, P3b amplitude was highly correlated across paradigms. The local effect differed clearly from the MMN, however. It occurred earlier than MMN and was followed by a much more prominent P3a. The peak latencies and amplitudes were also not correlated across paradigms. Caution should therefore be exercised when comparing the local effect and MMN across studies. We conclude that the within-individual MMN sensitivity is adequate for both the local-global and a dedicated MMN paradigm. The within-individual sensitivity of P3b was lower than expected for both the local-global and a dedicated P3b paradigm, which may explain the often-low sensitivity of P3b paradigms in patients with DoC.

A Time-Saving Alternative to "Peak-Picking" Algorithms: A Gaussian Mixture Model Feature Extraction Technique for the Neurodiagnostic Auditory Brainstem Response.

The accurate and efficient analysis of neurodiagnostic auditory brainstem responses (ABR) plays a critical role in assessing auditory pathway function in human and animal research and in clinical diagnosis. Traditional analysis of the neurodiagnostic ABR analysis involves visual inspection of the waveform and manually marking peaks and troughs. Visual inspection is a tedious and time-consuming task, especially in research where there may be hundreds or thousands of waveforms to analyze. "Peak-picking" algorithms have made this task faster; however, they are prone to the same errors as visual inspection. A Gaussian mixture model-based feature extraction technique (GMM-FET) is a descriptive model of ABR morphology and an alternative to peak-picking algorithms. The GMM-FET is capable of modeling multiple waves and accounting for wave interactions, compared with other template-matching approaches that fit single waves. The present study is a secondary analysis applying the GMM-FET to 321 ABRs from adult humans from 2 datasets using different stimuli and recording parameters. Goodness-of-fit of the GMM-FET to waves I and V and surrounding waves, that is, the summating potential and waves IV and VI, was assessed, and latency and amplitude estimations by the GMM-FET were compared with estimations from visual inspection. The GMM-FET had a similar success rate to visual inspection in extracting peak latency and amplitude, and there was low RMS error and high intraclass correlation between the model and response waveform. Mean peak latency differences between the GMM-FET and visual inspection were small, suggesting the two methods chose the same peak in the majority of waveforms. The GMM-FET estimated wave I amplitudes within 0.12 µV of visual inspection, but estimated larger wave V amplitudes than visual inspection. The results suggest the GMM-FET is an appropriate method for extracting peak latencies and amplitudes for neurodiagnostic analysis of ABR waves I and V.

Delays in latencies of median-nerve evoked magnetic fields in patients with succinic semialdehyde dehydrogenase deficiency

ObjectiveSuccinic semialdehyde dehydrogenase deficiency (SSADHD) is a genetic disorder resulting in abnormal regulation of γ-aminobutyric acid, lipid metabolism, and myelin biogenesis, leading to ataxia, seizures, and cognitive impairment. Since the myelin sheath is thinner in a murine model of SSADHD compared to a wild type, we hypothesized that this also holds for human brain. We tested whether the conduction velocity in the somatosensory pathway is accordingly delayed. MethodsSomatosensory evoked magnetic fields (SEF) produced by transcutaneous electrical stimulation of the median nerve were measured in 13 SSADHD patients, 11 healthy and 14 disease controls with focal epilepsy. The peak latencies of the initial four components (M1, M2, M3 and M4) were measured. ResultsThe SEF waveforms and scalp topographies were comparable across the groups. The latencies were statistically significantly longer in the SSADHD group compared to the two controls. We found these latencies for the SSADHD, healthy and disease controls respectively to be: M1: (21.9 ± 0.8 ms [mean ± standard error of the mean], 20.4 ± 0.6 ms, and 21.0 ± 0.4 ms) (p < 0.05); M2: (36.1 ± 1.0 ms, 33.1 ± 0.6 ms, and 32.1 ± 1.1 ms) (p < 0.005); M3: (62.5 ± 2.4 ms, 54.7 ± 2.0 ms, and 49.9 ± 1.8 ms) (p < 0.005); M4: (86.2 ± 2.3 ms, 78.8 ± 2.8 ms, and 73.5 ± 2.9 ms) (p < 0.005). ConclusionsThe SEF latencies are delayed in patients with SSADHD compared with healthy controls and disease controls. SignificanceThis is the first study that compares conduction velocities in the somatosensory pathway in SSADHD, an inherited disorder of GABA metabolism. The longer peak latency implying slower conduction velocity supports the hypothesis that myelin sheath thickness is decreased in SSADHD.

Spectral separation of evoked and spontaneous cortical activity, Part 1: Delta to high gamma band

Spectral analysis of repeatedly evoked potentials (EPs) is challenging since recordings contain a superposition of evoked signals and spontaneous activity. We developed a novel approach, N-interval Fourier Transform Analysis (N-FTA), which allows for reliable separation and simultaneous assessment of triggered and background spectral components. Median nerve stimulation data from a total of eleven volunteers recorded in two labs with different experimental settings were investigated. Consistently, short latency spectral components were mainly contained in the gamma and high gamma bands. In contrast, spontaneous activity displayed a 1/f spectral profile with distinct alpha and beta peaks. Spontaneous power spectral densities (PSDs) obtained for real and sham stimulation were highly comparable. The low frequency background PSD was more than two orders of magnitude above the spectral short latency peaks. Within the 30Hz to 90Hz band, the evoked peaks were -17dB to -4dB below the background suggesting that target band filtered short latency deflection might be extracted using less than 100 trials.SEPs following tibial nerve stimulation (3 subjects) displayed a narrower spectral band at about half the bandwidth as compared to median nerve stimulation. Evoked peaks were between 30Hz and 37Hz at PSD levels being -10dB to -4dB below the background activity. These spectral peaks were related to the short latency response of typical W-morphology.Cortical short latency responses are contained in distinct spectral target bands which are much narrower than the standard bandwidth recommendations for routine recordings. In particular, the high pass corner frequency may be selected about one order of magnitude above the current standard. This might render SEP recordings more robust since it eases the suppression of spontaneous activity and movement artifacts such as eye-blinks. Real-time zero-phase filters are required for translating these findings into improved recording systems.

Changes in Listening Effort Through Pupil Response After Atresioplasty in Children With Congenital Aural Atresia.

This study aimed to determine whether the improvement of hearing by surgical treatment alleviates cognitive demands through pupil response in patients with unilateral congenital aural atresia (CAA). A prospective study was performed on patients with unilateral CAA who were scheduled to undergo primary atresioplasty between November 2017 and May 2020. Pure-tone audiometry, auditory digit span test, Korean Speech Perception in Noise test, pupil measurement during speech tests, and questionnaires (Sound-Spatial-Qualities of Hearing Scale; subjective listening effort rating) were performed before and 6 months after surgery. Of 30 consecutive patients who initially enrolled, only 18 patients (12 males and 6 females) were included in the analysis. When the improvement of the air-bone gap and interaural difference of air conduction within 30 dB was defined as a successful hearing outcome, successful hearing improvement was achieved in 50% of the 18 patients. In pupil measurement, the success group had a significantly smaller mean pupil dilation response than the nonsuccess group at 0 and -3 dB signal to noise ratio (SNR) (all p < 0.01). In addition, significant differences were identified between the two groups for peak dilation and peak latency at all noise levels (all p < 0.01). When analyzing the change in pupil response before and after surgery, the difference in relative mean pupil dilation in the success group was significantly greater than that in the nonsuccess group at -3 dB SNR ( p = 0.02). In addition, the success group showed a significantly greater change in peak latency than the nonsuccess group at the -3 dB SNR ( p < 0.01). The difference in peak dilation tended to be greater in the success group than in the nonsuccess group, but the difference was not statistically significant. Patients with unilateral CAA who achieved surgically improved hearing had a smaller pupil dilation response than those who did not. These results suggest that successful hearing outcomes after surgery in patients with unilateral CAA may reduce the cognitive effort required to understand speech under difficult listening conditions.

The effect of cerebellar TMS on error processing: A combined single-pulse TMS and ERP study

Abstract The present study investigated temporal aspects of cerebellar contributions to the processing of performance errors as indexed by the error-related negativity (ERN) in the response-locked event-related potential (ERP). We co-registered EEG and applied single-pulse transcranial magnetic stimulation (spTMS) to the left posterolateral cerebellum and an extra-cerebellar control region (vertex) while healthy adult volunteers performed a Go/Nogo Flanker Task. In Go trials, TMS pulses were applied at four different time points, with temporal shifts of -100 ms, -50 ms, 0 ms, or +50 ms relative to the individual error latency (IEL, i.e., individual ERN peak latency + median error response time). These stimulation timings were aggregated into early (-100 ms, -50 ms) and late (0 ms, +50 ms) stimulation for the analysis. In Nogo trials, TMS pulses occurred 0 ms, 100 ms, or 300 ms after stimulus onset. Mixed linear model analyses revealed that cerebellar stimulation did not affect error rates overall. No effects were found for response times. As hypothesized, ERN amplitudes were decreased for cerebellar stimulation. No significant differences were found for the error positivity (Pe). Similar to TMS application to probe cerebellar-brain inhibition in the motor domain, the inhibitory tone of the cerebellar cortex may have been disrupted by the pulses. Reduced inhibitory output of the cerebellar cortex may have facilitated the processing of error information for response selection, which is reflected in a decreased ERN.

Optimal filters for ERP research II: Recommended settings for seven common ERP components.

In research with event-related potentials (ERPs), aggressive filters can substantially improve the signal-to-noise ratio and maximize statistical power, but they can also produce significant waveform distortion. Although this tradeoff has been well documented, the field lacks recommendations for filter cutoffs that quantitatively address both of these competing considerations. To fill this gap, we quantified the effects of a broad range of low-pass filter and high-pass filter cutoffs for seven common ERP components (P3b, N400, N170, N2pc, mismatch negativity, error-related negativity, and lateralized readiness potential) recorded from a set of neurotypical young adults. We also examined four common scoring methods (mean amplitude, peak amplitude, peak latency, and 50% area latency). For each combination of component and scoring methods, we quantified the effects of filtering on data quality (noise level and signal-to-noise ratio) and waveform distortion. This led to recommendations for optimal low-pass and high-pass filter cutoffs. We repeated the analyses after adding artificial noise to provide recommendations for data sets with moderately greater noise levels. For researchers who are analyzing data with similar ERP components, noise levels, and participant populations, using the recommended filter settings should lead to improved data quality and statistical power without creating problematic waveform distortion.

Carpal Tunnel Syndrome Electrodiagnostic Severity is Not Associated with PROMIS Upper Extremity, PROMIS Pain Interference and PROMIS Pain Intensity.

Background: The primary objective of this study was to determine the association between preoperative electrodiagnostic study (EDS) parameters and Patient-Reported Outcomes Measurement Information System (PROMIS) instruments in patients with EDS-confirmed carpal tunnel syndrome (CTS). Methods: A retrospective study of 45 patients with EDS-confirmed CTS was conducted. Patients completed the PROMIS Upper Extremity, PROMIS Pain Interference and PROMIS Pain Intensity. Explanatory variables included EDS disease severity (mild, moderate and severe), sensory peak latency, sensory amplitude, motor latency, motor amplitude, the presence of nonrecordable sensory latency and the presence of nonrecordable sensory amplitude. Explanatory variables also included patient-related factors, such as age, sex and diabetes mellitus. Associations between variables were assessed using simple linear regression, analysis of variance (ANOVA) and Student's t-test. Results: In our cohort, the EDS severity was mild in 38%, moderate in 42% and severe in 20% of patients. The mean PROMIS Upper Extremity score was 44.4, the mean PROMIS Pain Interference score was 53.5 and the mean PROMIS Pain Intensity score was 49.9. Bivariate analysis demonstrated no association between EDS severity overall or any EDS parameter individually and PROMIS Upper Extremity, PROMIS Pain Interference and PROMIS Pain Intensity. Diabetes mellitus was associated with poorer PROMIS Upper Extremity scores. Conclusions: EDS severity is not associated with PROMIS Upper Extremity, PROMIS Pain Interference and PROMIS Pain Intensity. Carpal tunnel release is commonly indicated for pain and dysfunction, but validated measures of pain and dysfunction do not correlate with EDS severity. Level of Evidence: Level III (Diagnostic).

Localizing seizure onset zone by a cortico-cortical evoked potentials-based machine learning approach in focal epilepsy

ObjectiveWe aimed to develop a new approach for identifying the localization of the seizure onset zone (SOZ) based on corticocortical evoked potentials (CCEPs) and to compare the connectivity patterns in patients with different clinical phenotypes. MethodsFifty patients who underwent stereoelectroencephalography and CCEP procedures were included. Logistic regression was used in the model, and six CCEP metrics were input as features: root mean square of the first peak (N1RMS) and second peak (N2RMS), peak latency, onset latency, width duration, and area. ResultsThe area under the curve (AUC) for localizing the SOZ ranged from 0.88 to 0.93. The N1RMS values in the hippocampus sclerosis (HS) group were greater than that of the focal cortical dysplasia (FCD) IIa group (p < 0.001), independent of the distance between the recorded and stimulated sites. The sensitivity of localization was higher in the seizure-free group than in the non-seizure-free group (p = 0.036). ConclusionsThis new method can be used to predict the SOZ localization in various focal epilepsy phenotypes. SignificanceThis study proposed a machine-learning approach for localizing the SOZ. Moreover, we examined how clinical phenotypes impact large-scale abnormality of the epileptogenic networks.

Evaluating the effectiveness of artifact correction and rejection in event-related potential research.

Eyeblinks and other large artifacts can create two major problems in event-related potential (ERP) research, namely confounds and increased noise. Here, we developed a method for assessing the effectiveness of artifact correction and rejection methods in minimizing these two problems. We then used this method to assess a common artifact minimization approach, in which independent component analysis (ICA) is used to correct ocular artifacts, and artifact rejection is used to reject trials with extreme values resulting from other sources (e.g., movement artifacts). This approach was applied to data from five common ERP components (P3b, N400, N170, mismatch negativity, and error-related negativity). Four common scoring methods (mean amplitude, peak amplitude, peak latency, and 50% area latency) were examined for each component. We found that eyeblinks differed systematically across experimental conditions for several of the components. We also found that artifact correction was reasonably effective at minimizing these confounds, although it did not usually eliminate them completely. In addition, we found that the rejection of trials with extreme voltage values was effective at reducing noise, with the benefits of eliminating these trials outweighing the reduced number of trials available for averaging. For researchers who are analyzing similar ERP components and participant populations, this combination of artifact correction and rejection approaches should minimize artifact-related confounds and lead to improved data quality. Researchers who are analyzing other components or participant populations can use the method developed in this study to determine which artifact minimization approaches are effective in their data.

Altered brain function and structure in carpal tunnel syndrome: a systematic review and meta-analysis of structural and functional brain imaging.

This systematic review with a meta-analysis aimed to identify the altered brain structure and function in carpal tunnel syndrome (CTS) by summarizing the literature about magnetic resonance imaging (MRI), functional magnetic resonance imaging (fMRI), and magnetoencephalography (MEG) outcomes compared to healthy controls (HC). CTS is the most common nerve entrapment in the arm associated with altered peripheral and central nociceptive system. PRISMA guidelines were used to report the outcomes. Six databases were searched for relevant literature (Web of Science, Scopus, PubMed, Sage, EBSCO host, and Cochrane). Eligible studies comparing MRI, fMRI, and MEG findings in people with CTS (present for at least 2months) and HC through the following parameters: (1) interdigit cortical separation distance, (2) white and grey matter changes, (3) peak latency of M20 wave and recovery function of N20 from the somatosensory cortex (SI), and (4) surface area of activated digit cortical representation. The results from different studies were pooled and a meta-analysis was done. From 17 included, there was a significant reduction of interdigit cortical separation distance of index-middle and index-little fingers in the CTS (SMD = -0.869, 95% CI (-1.325, -0.413), p-value = 0.000) and (SMD = -0.79, 95% CI (-1.217, -0.364), p-value = 0.000), respectively. Middle-little fingers interdigit separation showed no difference (SMD = -0.2, 95% CI (-0.903, 1.309), p-value = 0.718). There is evidence supporting the altered brain structure and function in CTS as evidenced by reduction of interdigit cortical separation distance, and excessive blurring and disinhibition of SI, with low resting state functional connectivity. Thus, centrally directed therapeutic approaches might complement peripheral treatments.

Feedback Type May Change the EMG Pattern and Kinematics During Robot Supported Upper Limb Reaching Task.

Haptic interfaces and virtual reality (VR) technology have been increasingly introduced in rehabilitation, facilitating the provision of various feedback and task conditions. However, correspondence between the feedback/task conditions and movement strategy during reaching tasks remains a question. To investigate movement strategy, we assessed velocity parameters and peak latency of electromyography. Ten neuromuscularly intact volunteers participated in the measurement using haptic interface and VR. Concurrent visual feedback and various terminal feedback (e.g., visual, haptic, visual and haptic) were given. Additionally, the object size for the reaching task was changed. The results demonstrated terminal haptic feedback had a significant impact on kinematic parameters; showed [Formula: see text] s ([Formula: see text]) shorter movement time and [Formula: see text] m/s ([Formula: see text]) higher mean velocity compared to no terminal feedback. Also, smaller peak latency was observed in different muscle regions based on the object size.

Association between freezing of gait and anticipatory postural adjustments in Parkinson's disease.

[Purpose] One-leg standing motion was measured in patients with Parkinson's disease (PD) to evaluate the association between freezing of gait (FOG) and anticipatory postural adjustments (APA). [Participants and Methods] The participants included10 healthy older individuals, seven patients with PD without FOG (PD-FOG group), and seven patients with PD and FOG (PD+FOG group). An accelerometer that was built into a smartphone was attached to the lower back of each participant, and acceleration in the mediolateral direction was measured during one-leg standing. For the mediolateral component of acceleration, the time to the maximum value in the stance direction (peak latency, PL) and the amount of displacement of the maximum value (peak magnitude, PM) were analyzed as APA features. A one-way analysis of variance (ANOVA) was used to compare PL and PM among the three groups. In addition, the APA ratio (APAr), which is the ratio of PL to PM, was compared between study cohorts. [Results] Delayed PL and decreased PM were observed in the PD+FOG group, compared with the older and PD-FOG groups. In addition, APAr levels were significantly lower in the PD+FOG group. [Conclusion] Patients with PD with FOG had greater APA impairment than those with PD without FOG.

Effect of Short-term Yoga Training on Cervical and Ocular Vestibular Evoked Myogenic Potentials in Healthy Adults

Purpose: The present study aimed to assess the effect of practicing yoga on the functioning of sacculo-collic and utriculo-ocular pathways using cervical and ocular vestibular evoked myogenic potential (cVEMP and oVEMP). Methods: A total of 10 healthy young adults aged 20–25 years participated in the study. Audiological evaluation including pure-tone audiometry, immittance, and otoacoustic emission, cVEMP, and oVEMP was done to ensure a normal functioning audio-vestibular system. Short-term yoga training was provided for all the participants for 10 days, spanning over 2 weeks. It was 1 h/session/day. The latency and peak-to-peak amplitude of cVEMP and oVEMP responses were noted and analyzed before and after yoga training. Results: Paired sample t-test results showed significantly better peak-to-peak amplitude of both cVEMP and oVEMP after short-term yoga training in healthy individuals. The latency of both cVEMP and oVEMP peaks did not show a significant difference before and after yoga training. Conclusion: Short-term yoga training positively affected the functioning of sacculo-collic and utriculo-ocular pathways, leading to enhanced cVEMP and oVEMP responses.

Revisiting the Chicken Auditory Brainstem Response: Frequency Specificity, Threshold Sensitivity, and Cross Species Comparison.

The auditory brainstem response (ABR) is important for both clinical and basic auditory research. It is a non-invasive measure of hearing function with millisecond-level precision. The ABR can not only measure the synchrony, speed, and efficacy of auditory physiology but also detect different modalities of hearing pathology and hearing loss. ABRs are easily acquired in vertebrate animal models like reptiles, birds, and mammals, and complement existing molecular, developmental, and systems-level research. One such model system is the chicken; an excellent animal for studying auditory development, structure, and function. However, the ABR for chickens was last reported nearly 4 decades ago. The current study examines how decades of ABR characterization in other animal species support findings from the chicken ABR. We replicated and expanded on previous research using 43 chicken hatchlings 1- and 2-day post-hatch. We report that click-evoked chicken ABRs presented with a peak waveform morphology, amplitude, and latency like previous avian studies. Tone-evoked ABRs were found for frequencies from 250 to 4000 Hertz (Hz) and exhibited a range of best sensitivity between 750 and 2000 Hz. Objective click-evoked and tone-evoked ABR thresholds were comparable to subjective thresholds. With these revisited measurements, the chicken ABR still proves to be an excellent example of precocious avian development that complements decades of molecular, neuronal, and systems-level research in the same model organism.

Gender Effect on Neural Correlates of Autobiographical False Memories for Brand Images.

This study investigated the effect of autobiographical brand images on false memory formation in adults, using the category associate's procedure. The study also applied the event-related potential (ERP) approach to explore neural correlates of false memory and gender differences in false memory recall of brand images. Eight categories of autobiographical brand images were implied in a category associates' procedure to investigate false memory recall. ERP data were obtained from 24 participants (12 females and 12 males) using a 32-channel amplifier while subjects were performing the memory task. Subsequently, gender effects on behavioral responses and neural correlates of false and true memory recalls were statistically compared using peak amplitude and latency of P300, late positive complex, and FN400 components. The results showed that left frontal areas in women were more activated in response to false memories compared to men, however, the men's brain responses were faster. In addition, the men's brain responses to false memories were widely distributed mainly over frontal, parietal, and occipital areas. Males and females differently process autobiographical brand images. Nevertheless, the differential neural process may not influence their recognition rate or response time.

Effects of pain associated with orthodontic tooth movement on tactile sensation of periodontal ligaments

ObjectivesPain associated with orthodontic tooth movement reportedly reduces periodontal ligament tactile sensation. However, the mechanism associated with the central nervous system remains unclear. This study was conducted by measuring somatosensory evoked magnetic fields (SEFs) during mechanical stimulation of teeth as they were being moved by separator elastics. Findings clarified the effects of pain on periodontal ligament tactile sensation during orthodontic tooth movement.Materials and MethodsUsing magnetoencephalography, SEFs were measured during the application of mechanical stimuli to the mandibular right first molars of 23 right-handed healthy participants (0 h). Separator elastics were subsequently inserted into the mesial and distal interdental portions of the mandibular right first molars. The same mechanical stimuli were applied again 24 h later while the SEFs were measured (24 h). After each SEF measurements, pain was also evaluated using the Visual Analog Scale (VAS).ResultsThe VAS values were significantly higher at 24 h than at 0 h (p < 0.05). No significant difference in the peak latencies was found between those obtained at 0 h and 24 h, but the intensities around 40.0 ms in the contralateral hemisphere were significantly lower at 24 h than at 0 h (p < 0.01).ConclusionsPain associated with orthodontic tooth movement might suppress periodontal ligament tactile sensation in the primary somatosensory cortex.Clinical RelevancePain associated with orthodontic tooth movement might affect periodontal ligament sensation, consequently causing discomfort during occlusion.

Evoked potential response in patients with idiopathic Parkinson’s disease and atypical parkinsonian syndromes: A comparative study

Patients with idiopathic Parkinson&amp;rsquo;s disease (IPD) and atypical parkinsonian syndromes (APSs) suffer from a range of disorders, especially in balance and locomotion, which necessitate visual, auditory, and somatosensory inputs. In this study, IPD patients, APS patients, and healthy controls (HCs) (n = 50 per group) underwent a series of assessments for visual evoked potentials (VEP), brainstem auditory evoked response (BAER), and short-latency somatosensory evoked potentials (SSEP). Results showed that VEP P100 latency was prolonged in multiple system atrophy-cerebellar type (MSA-C), multiple system atrophy-parkinsonian type (MSA-P), and corticobasal ganglionic degeneration (CBD) patients. The latency of peaks III and V was prolonged in IPD, MSA-C, dementia with Lewy bodies (DLB), and Parkinson&amp;rsquo;s disease dementia (PDD). BAER I-III and I-V interpeak latency were prolonged in IPD, DLB, and PDD, whereas BAER I-III, III-V, and I-V interpeak latencies were increased and the V/I amplitude ratio was decreased in MSA-C. The central sensory conduction time (N20-N13) was increased in MSA-P and MSA-C in SSEP. IPD patients had prolonged VEP P100 latency (P &lt; 0.001), lower VEP N75-P100 amplitude (P &lt; 0.001), prolonged BAER I, II, II, IV, V peak latencies (P &lt; 0.001), I-III, I-V interpeak latencies (P &lt; 0.001), lower BAER V/I amplitude ratio (P &lt; 0.001), and prolonged SSEP N13, N20, central sensory conduction time (N20-N13) (P &lt; 0.001) than HCs. IPD patients also had prolonged BAER I, II, II, IV, V peak latencies (P &lt; 0.001), prolonged I-III, I-V interpeak latencies (P &lt; 0.001), and shorter SSEP N13, N20, central sensory conduction time (N20-N13) (P &lt; 0.001) than APS patients. Moreover, APS patients had prolonged VEP P100 and N145 latencies (P &lt; 0.001) and decreased N75-N145 amplitude (P &lt; 0.001) compared to HCs. APS patients also had prolonged BAER II, II, IV, V peak latencies (P &lt; 0.001), prolonged I-III, III-V, I-V interpeak latencies (P &lt; 0.001), decreased V/I amplitude ratio, and prolonged SSEP N13, N20, central sensory conduction time (N20-N13) (P &lt; 0.001) than HCs. Postural instability and gait disorder (PIGD) IPD had significantly prolonged BAER III, V peak latencies (P &lt; 0.05), and prolonged III-V interpeak latencies (P &lt; 0.05) compared to tremor-dominant IPD. Overall, the IPD and APS patients had significant VEP, BAER, and SSEP abnormalities of demyelination and axonal variety in the visual, auditory, and somatosensory pathways. The changes were also correlated with the disease duration and severity. Although the diseases are predominantly motor disorders with significant non-motor components, these electrophysiological abnormalities might open a new avenue to assess the non-motor symptoms.

Cortical responses time-locked to continuous speech in the high-gamma band depend on selective attention.

Auditory cortical responses to speech obtained by magnetoencephalography (MEG) show robust speech tracking to the speaker's fundamental frequency in the high-gamma band (70-200 Hz), but little is currently known about whether such responses depend on the focus of selective attention. In this study 22 human subjects listened to concurrent, fixed-rate, speech from male and female speakers, and were asked to selectively attend to one speaker at a time, while their neural responses were recorded with MEG. The male speaker's pitch range coincided with the lower range of the high-gamma band, whereas the female speaker's higher pitch range had much less overlap, and only at the upper end of the high-gamma band. Neural responses were analyzed using the temporal response function (TRF) framework. As expected, the responses demonstrate robust speech tracking of the fundamental frequency in the high-gamma band, but only to the male's speech, with a peak latency of ~40 ms. Critically, the response magnitude depends on selective attention: the response to the male speech is significantly greater when male speech is attended than when it is not attended, under acoustically identical conditions. This is a clear demonstration that even very early cortical auditory responses are influenced by top-down, cognitive, neural processing mechanisms.

Auditory brainstem responses in the nine-banded armadillo (Dasypus novemcinctus).

The auditory brainstem response (ABR) to tone burst stimuli of thirteen frequencies ranging from 0.5 to 48 kHz was recorded in the nine-banded armadillo (Dasypus novemcinctus), the only extant member of the placental mammal superorder Xenarthra in North America. The armadillo ABR consisted of five main peaks that were visible within the first 10 ms when stimuli were presented at high intensities. The latency of peak I of the armadillo ABR increased as stimulus intensity decreased by an average of 20 μs/dB. Estimated frequency-specific thresholds identified by the ABR were used to construct an estimate of the armadillo audiogram describing the mean thresholds of the eight animals tested. The majority of animals tested (six out of eight) exhibited clear responses to stimuli from 0.5 to 38 kHz, and two animals exhibited responses to stimuli of 48 kHz. Across all cases, the lowest thresholds were observed for frequencies from 8 to 12 kHz. Overall, we observed that the armadillo estimated audiogram bears a similar pattern as those observed using ABR in members of other mammalian clades, including marsupials and later-derived placental mammals.