Delayed P100-Like Latencies in Multiple Sclerosis: A Preliminary Investigation Using Visual Evoked Spread Spectrum Analysis

Prolonged Visual Evoked Potential Latencies in Dogs Naturally Infected with Canine Distemper Virus

Canine distemper (CD) is a deadly, multi-system infection caused by a Morbillivirus. The canine distemper virus (CDV) frequently affects the nervous system with demyelinating leukoencephalitis, the most common neurological lesion. The disease has been linked to multiple sclerosis (MS) in humans due to similar clinical presentation and pathophysiological mechanisms. In MS, visual evoked potentials (VEPs) have been identified as a reliable marker for disease progression, enabling the early detection of clinically suspected lesions. The aim of this study was to determine if there are any abnormalities in VEP responses in dogs with neurological CD. Visual evoked potentials and electroretinogram (ERG) were recorded at both the cranial and spinal levels in dogs naturally infected with CDV and in healthy dogs. The results in the CDV-infected group revealed a bilateral increase in the latency of N1, P1, N2, P2, and N3 waves of the VEPs, without any alterations in their amplitudes. No significant differences were observed in the ERG between the groups. These results suggest that altered VEP responses could serve as an early diagnostic indicator of neurological damage caused by distemper. Therefore, conducting these studies could potentially aid in the detection of central nervous conduction disorders during the subclinical phases of the disease.

Electroneuromyography comparison between pre-elderly adult females with and without MS; the potential role of a mind-body therapy in improving neurophysiological profile of MS during pandemic

INTRODUCTION

Imaginary exercises seem to be useful therapeutic approaches to modulate neuromuscular functions due to two main reasons: first, this training would not greatly increase body temperature, and secondly, it can positively affect brain-muscle pathways-which are both primary factors should be considered in rehabilitation programs for patients with multiple sclerosis (MS).

METHOD

32 pre-elderly adult females with relapsing-remitting MS (n = 16 - age M (SD): 56.75 (5.07)) and without MS (n = 16 - age M (SD): 56.56 (4.35)) voluntarily recruited. First, they were assigned into two groups: MS patients and healthy controls, to investigate baseline between-group comparison. Then, MS patients were randomly divided into two groups of eight each, designated as experimental and control groups. Recording the nerve conduction velocity (NCV) of tibial nerve and integrated electromyographic muscle activation (IEMG) of gastrocnemius muscle was conducted twice, before and after a six-week mind-body exercise therapy to evaluate its effectiveness on improving neuromuscular function.

RESULTS

The results showed significant difference in both tibial NCV (P < 0.001) and IEMG (P = 0.001) variables between non-MS group and MS group. Furthermore, there was a significant main effect of intervention (P = 0.05) and time (P < 0.001) on IEMG in the MS group, while there was no significant effect of intervention (P = 0.18) and time (P = 0.23) on NCV (p = 0.89).

CONCLUSION

Neuromuscular dysfunction were apparent in MS patients, and a mind-body therapy of imagery isometric training was found to be useful on improving the neurological deficit in women with MS.

TRIAL REGISTRATION NUMBER

UMIN000046935.

Unveiling Visual Physiology and Steady-State Evoked Potentials using Low-Cost and Transferable Electroencephalography for Evaluating Neuronal Activation

Purpose

The ability to see and process images depends on the function of the eyes and the processing of visual information by neurons in the cerebral cortex, something that could be measured through electroencephalography (EEG). Although the EEG is used to evaluate visual pathways in children and demyelination diseases, the limited utilization of brain recording techniques in other applications like therapy is primarily due to budget constraints. The goal of this paper is to demonstrate results from studying brain aspects of vision, utilizing measurements based on oscillatory activity analysis, low-cost, portable equipment, and a processing pipeline relying on Python's open-source libraries. These studies involve healthy subjects who wear glasses to assess changes in visual perception.

Methods

First, electroencephalographic signals were recorded while the subjects observed a visually standardized stimulus. The signals were processed and filtered to reduce artifacts, and the power spectral density (PSD) was calculated to observe the presence of steady-state visual potentials (VEP) to confirm the capture of neuronal activation to the visual stimulus.

Results

It was possible to establish a difference between subjects wearing and not wearing their glasses, allowing validation that the information acquired with the transferable equipment is adequate for the analysis of neuronal activity related to visual processing, opening the possibility to be used in future studies in therapy.

Conclusion

This study contributes to the development of cost-effective and portable EEG solutions for visual system analysis. It demonstrates the potential for applying transferable EEG devices in clinical settings and highlights the importance of tailored visual stimuli for reliable neural activation.

Modulation of the neuronal response in human primary visual cortex by re-entrant projections during retinal input processing as manifest in the visual evoked potential

Initial deflections in the visual evoked potential (VEP) reflect the neuronal process of extracting features from the retinal input; a process not modulated by re-entrant projections. Later deflections in the VEP reflect the neuronal process of combining features into an object, a process referred to as 'object closure' and modulated by re-entrant projections. Our earlier work indicated that the VEP reflects independent neuronal responses processing temporal - and spatial luminance contrast and that these responses arise from an interaction between forward and re-entrant input. In this earlier work, changing the temporal luminance contrast property of a stimulus altered its spatial luminance contrast property. We recorded the VEP in 12 volunteers viewing image pairs of a windmill, regular dartboard or an RMS dartboard rotated by either Π/4, Π/2, 3Π/4 or Π radians with respect to each other. The windmill and regular dartboard had identical white to black ratio, while the two dartboards identical contrast edges per unit area. Rotation varied temporal luminance contrast of a stimulus without affecting its spatial luminance contrast. N75, P100, N135 and P240 amplitude and latency were compared and a source localisation and temporal frequency analysis performed. P100 amplitude signals a neuronal response processing temporal luminance contrast that is modulated by re-entrant projections with fast axonal conduction velocities. N135 and P240 signal the neuronal response processing spatial luminance contrast and is modulated by re-entrant projections with slow axonal conduction velocities. The dorsal stream is interconnected by fast axonal conduction velocities, the ventral stream by slow axonal conduction velocities.

Individual differences in visual evoked potential latency are associated with variance in brain tissue volume in people with multiple sclerosis: An analysis of brain function-structure correlates

Visual evoked potentials (VEP) index visual pathway functioning, and are often used for clinical assessment and as outcome measures in people with multiple sclerosis (PwMS). VEPs may also reflect broader neural disturbances that extend beyond the visual system, but this possibility requires further investigation. In the present study, we examined the hypothesis that delayed latency of the P100 component of the VEP would be associated with broader structural changes in the brain in PwMS. We obtained VEP latency for a standard pattern-reversal checkerboard stimulus paradigm, in addition to Magnetic Resonance Imaging (MRI) measures of whole brain volume (WBV), gray matter volume (GMV), white matter volume (WMV), and T2-weighted fluid attenuated inversion recovery (FLAIR) white matter lesion volume (FLV). Correlation analyses indicated that prolonged VEP latency was significantly associated with lower WBV, GMV, and WMV, and greater FLV. VEP latency remained significantly associated with WBV, GMV, and WMV even after controlling for the variance associated with inter-ocular latency, age, time between VEP and MRI assessments, and other MRI variables. VEP latency delays were most pronounced in PwMS that exhibited low volume in both white and gray matter simultaneously. Furthermore, PwMS that had delayed VEP latency based on a clinically relevant cutoff (VEP latency ≥ 113 ms) in both eyes had lower WBV, GMV, and WMV and greater FLV in comparison to PwMS that had normal VEP latency in one or both eyes. The findings suggest that PwMS that have delayed latency in both eyes may be particularly at risk for exhibiting greater brain atrophy and lesion volume. These analyses also indicate that VEP latency may index combined gray matter and white matter disturbances, and therefore broader network connectivity and efficiency. VEP latency may therefore provide a surrogate marker of broader structural disturbances in the brain in MS.

A Hybrid Approach for MS Diagnosis Through Nonlinear EEG Descriptors and Metaheuristic Optimized Classification Learning

Multiple sclerosis (MS), a disease of the central nervous system, affects the white matter of the brain. Neurologists interpret magnetic resonance images that are often complicated, time-consuming, and contradictory. Using EEG signals, this disease can be analyzed and diagnosed more accurately. However, it is imperative that MS be diagnosed by specialists using assistive technology. Until now, a few methods have been proposed in this field that are sometimes associated with different challenges in analysis. This paper presents a hybrid approach to MS diagnosis in order to decrease classification error rates. Using the proposed method, EEG descriptors in both the time and frequency domains are analyzed. After the feature extraction stage, a modified version of the ant colony optimization method (m-ACO) was used to select the appropriate subset of features. Then, the support vector machine is used to determine whether the disease exists. A metaheuristic algorithm adjusts the support vector machine's parameters to withstand overfitting challenges. Despite a limited number of input channels, significant classification accuracy has been achieved using wavelet analysis techniques, dividing all five subbands of EEG signals, signal windowing, and extracting efficient features from the data. Additionally, alpha, beta, and gamma bands of the signal are important, and the accuracy, sensitivity, and specificity levels are higher than 98.5%. Compared to similar MS diagnostic methods, the proposed method achieved significantly higher diagnostic accuracy. Application and implementation of this method can be effective in treating neurological diseases, including multiple sclerosis.

Parallel processing in human visual cortex revealed through the influence of their neural responses on the visual evoked potential

The neural response in the human visual system is composed of magno-, parvo- and koniocellular input from the retina. Signal differences from functional imaging between health and individuals with a cognitive weakness are attributed to a dysfunction of a specific retinal input. Yet, anatomical interconnections within the human visual system obscure individual contribution to the neural response in V1. Deflections in the visual evoked potential (VEP) arise from an interaction between electric dipoles, their strength determined by the size of the neural population active during temporal - and spatial luminance contrast processing. To investigate interaction between these neural responses, we recorded the VEP over visual cortex of 14 healthy adults viewing four series of windmill patterns. Within a series, the relative area white in a pattern varied systematically. Between series, the number of sectors across which this area was distributed doubled. These patterns were viewed as pattern alternating and on-/off stimuli. P100/P1 amplitude increased linearly with the relative area white in the pattern, while N135/N1 and P240/P2 amplitude increased with the number of sectors of which the area white was distributed. The decreases P100 amplitude with increasing number of sectors is attributed to an interaction between electric dipoles located in granular and supragranular layers of V1. Differences between the VEP components obtained during a pattern reversing display and following pattern onset are accounted for by the transient and sustained nature of neural responses processing temporal - and spatial luminance contrast and ability of these responses to manifest in the VEP.

Pattern-Reversal Visual Evoked Potential in Children With Congenital Zika Syndrome

PURPOSE

To objectively evaluate the visual function in children with congenital Zika syndrome using pattern-reversal visual evoked potential (PR-VEP).

METHODS

This was a cross-sectional study composed of two patient groups: children aged between 18 and 24 months who were positive for the Zika virus (congenital Zika syndrome group) and age-matched healthy children (control group). All patients underwent a comprehensive ophthalmologic examination and PR-VEP was performed binocularly in a room with constant dim illumination. The P100 peak time in the 60' arc stimuli was used, and the results were correlated with visual acuity, cephalic perimeter at birth, and funduscopic findings.

RESULTS

Thirty-seven children were included in the congenital Zika syndrome group and 15 in the control group. The mean age was 18.5 ± 0.9 months (range: 17 to 20 months) in the congenital Zika syndrome group and 24.3 ± 1.6 months (range: 21 to 28 months) in the control group. The P100 response was normal in 7 patients (18.9%) with congenital Zika syndrome, borderline in 2 (5.4%), abnormal with prolonged latency in 18 (48.6%), and abnormal with no response in 10 (27.0%). A significant correlation between the visual acuity and P100 peak time was observed (P < .001). The P100 values were not correlated significantly with the cephalic perimeter at birth (P = .412) or the funduscopic findings (P = .510). PR-VEP in children with congenital Zika syndrome and no funduscopic findings was significantly worse than in the control group (P = .001).

CONCLUSIONS

Children with congenital Zika syndrome have characteristically abnormal PR-VEPs regardless of the funduscopic findings and severe microcephaly. The PR-VEP findings supported the diagnosis of cortical visual impairment in these children. [J Pediatr Ophthalmol Strabismus. 2021;58(2):78-83.].

Normative values of visual evoked potentials in Northeastern of Iran

PURPOSE

Visual evoked potentials (VEPs) provide important diagnostic information related to the functional integrity of the visual pathways. The aim of this study was to establish normative values of different components of pattern reversal VEPs on Iranian normal adult subjects.

METHODS

Monocular and binocular pattern reversal VEPs were recorded on 59 healthy participants (22.55±3.79 years old) using the Roland RETI system for two check sizes of 15 and 60min of arc. The measured VEP components were the latencies of N75, P100, N135 and amplitude of N75-P100.

RESULTS

Repeated measures ANOVA showed that viewing eye condition has a significant impact on the amplitude of N75-P100 (P<0.001, F=13.89). Also, the effect of check size on the latencies of N75, P100, N135, amplitude of N75-P100 (P≤0.010), as well as the intraocular difference of P100 latency and amplitude N75-P100 (P=0.007) was significant. More specifically, the amplitude of N75-P100 in both check sizes significantly differed between gender groups (P<0.023).

CONCLUSION

According to the results of this study, VEPs components are affected by the stimulus size, monocular and binocular recording conditions and gender. Therefore, it is necessary to determine the normative values of VEPs in each population, so that the results could be used in clinical studies.

A Study of the Correlation between VEP and Clinical Severity in Children with Autism Spectrum Disorder

Visual evoked potential (VEP) is a technique used to assess the brain's electrical response to visual stimuli. The aims of this study were to examine neural transmission within the visual pathway through VEP testing in preschool children with autism spectrum disorder (ASD) and compare it to age-matched controls, as well as search for a correlation between the VEP parameters and the symptoms of ASD. Participants were composed of ASD children (9 males) and typically developing children (8 males and 4 females), aged between 3 and 5 years. Checkerboards were chosen as the pattern-reversal VEP. The clinical severity of ASD was assessed using the Autism Treatment Evaluation Checklist (ATEC) and the Vineland Adaptive Behavior Scales 2nd edition (VABS-II). Our findings demonstrated that children with ASD had significantly longer N145 latency compared to the controls. A longer N145 latency correlated with a higher score of ATEC within the sensory/cognitive awareness subdomain. In addition, a slower N145 response was also associated with a lower VABS-II score within the socialization domain. The correlation between longer VEP latency and abnormal behaviors in children with ASD suggests a delayed neural communication within other neural circuits, apart from the visual pathway. These lines of evidence support the possibility of using VEP, along with clinical parameters, for the assessment of ASD severity.