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Background: A key challenge in steady-state visual evoked potential (SSVEP)- based brain-computer interface (BCI) systems is to effectively recognize frequencies within a short time window. To address this challenge, the specific characteristics of the data are needed to select the frequency recognition method. These characteristics include factors, such as the number of stimulation targets and the presence of harmonic frequencies, resulting in optimizing the performance and accuracy of SSVEP-based BCI systems. Objective: The current study aimed to examine the effect of data characteristics on frequency recognition accuracy. Material and Methods: In this analytical study, five commonly used frequency recognition methods were examined, used to various datasets containing different numbers of frequencies, including sub-data with and without frequency harmonics. Results: The increase in the number of frequencies in the Multivariate Linear Regression (MLR) method has led to a decrease in frequency recognition accuracy by 9%. Additionally, the presence of harmonic frequencies resulted in an 8% decrease in accuracy for the MLR method. Conclusion: Frequency recognition using the MLR method reduces the effect of the number of different frequencies and harmonics of the stimulation frequencies on the frequency recognition accuracy. [ABSTRACT FROM AUTHOR]

Studying states and state transitions in the brain is challenging due to nonlinear, complex dynamics. In this research, we analyze the brain's response to non-invasive perturbations. Perturbation techniques offier a powerful method for studying complex dynamics, though their translation to human brain data is under-explored. This method involves applying small inputs, in this case via photic stimulation, to a system and measuring its response. Sensitivity to perturbations can forewarn a state transition. Therefore, biomarkers of the brain's perturbation response or "cortical excitability" could be used to indicate seizure transitions. However, perturbing the brain often involves invasive intracranial surgeries or expensive equipment such as transcranial magnetic stimulation (TMS) which is only accessible to a minority of patient groups, or animal model studies. Photic stimulation is a widely used diagnostic technique in epilepsy that can be used as a non-invasive perturbation paradigm to probe brain dynamics during routine electroencephalography (EEG) studies in humans. This involves changing the frequency of strobing light, sometimes triggering a photo-paroxysmal response (PPR), which is an electrographic event that can be studied as a state transition to a seizure state. We investigate alterations in the response to these perturbations in patients with genetic generalized epilepsy (GGE), with (n = 10) and without (n = 10) PPR, and patients with psychogenic non-epileptic seizures (PNES; n = 10), compared to resting controls (n = 10). Metrics of EEG time-series data were evaluated as biomarkers of the perturbation response including variance, autocorrelation, and phase-based synchrony measures. We observed considerable differences in all group biomarker distributions during stimulation compared to controls. In particular, variance and autocorrelation demonstrated greater changes in epochs close to PPR transitions compared to earlier stimulation epochs. Comparison of PPR and spontaneous seizure morphology found them indistinguishable, suggesting PPR is a valid proxy for seizure dynamics. Also, as expected, posterior channels demonstrated the greatest change in synchrony measures, possibly reflecting underlying PPR pathophysiologic mechanisms. We clearly demonstrate observable changes at a group level in cortical excitability in epilepsy patients as a response to perturbation in EEG data. Our work re-frames photic stimulation as a non-invasive perturbation paradigm capable of inducing measurable changes to brain dynamics. [ABSTRACT FROM AUTHOR]

Background: Pain is a contributing factor to the low compliance rate for performing a colonoscopy on screening for colorectal cancer. Purpose: This meta-analysis aimed to evaluate the effect of visual distraction on adults undergoing colonoscopy. Methods: We searched PubMed, EMBASE, Web of Science, and Cochrane Library Database from their inception to February 2022. Randomized controlled trials comparing visual distraction with non-visual distraction were considered for inclusion. The fixed-effects and random-effects models were used to pool the data from individual studies and the Cochrane risk of bias assessment tool was used to determine the methodology quality. Results: This meta-analysis included four studies (N = 301) for pain level and total procedure time, three studies (N = 181) for satisfaction score, three studies (N = 196) for anxiety level, and four studie (N = 402) for willingness to repeat the procedure. The pooled analysis shown that significantly lower pain levels (SMD, − 0.25; 95% CI − 0.47 to − 0.02; P = 0.03), higher satisfaction score with the procedure (SMD, 0.63; 95% CI, 0.33 to 0.93; P < 0.0001), and higher willingness to repeat the procedure (OR, 2.66; 95% CI 1.70 to 4.17; P < 0.0001) in the visual distraction group than those in the non-visual distraction group, with no significant differences in total procedure time (SMD,− 0.07; 95% CI − 0.30 to 0.15; P = 0.53) or anxiety level (SMD,− 0.27; 95% CI − 0.55 to 0.01; P = 0.06). Conclusions: Visual distraction improved the patient's pain, satisfaction, and willingness to repeat the procedure. Thus, visual stimulation is an effective way to reduce pain during colonoscopy and should be recommended. [ABSTRACT FROM AUTHOR]

Objective: The switch between nonseizure and seizure states involves profound alterations in network excitability and synchrony. In this study, we aimed to identify and compare features of neural excitability and dynamics across multiple zebrafish seizure and epilepsy models. Methods: Inspired by video‐electroencephalographic recordings in patients, we developed a framework to study spontaneous and photically evoked neural and locomotor activity in zebrafish larvae, by combining high‐throughput behavioral tracking and whole‐brain in vivo two‐photon calcium imaging. Results: Our setup allowed us to dissect behavioral and physiological features that are divergent or convergent across multiple models. We observed that spontaneous locomotor and neural activity exhibit great diversity across models. Nonetheless, during photic stimulation, hyperexcitability and rapid response dynamics were well conserved across multiple models, highlighting the reliability of photically evoked activity for high‐throughput assays. Intriguingly, in several models, we observed that the initial elevated photic response is often followed by rapid decay of neural activity and a prominent depressed state. Elevated photic response and following depressed state in seizure‐prone networks are significantly reduced by the antiseizure medication valproic acid. Finally, rapid decay and depression of neural activity following photic stimulation temporally overlap with slow recruitment of astroglial calcium signals that are enhanced in seizure‐prone networks. Significance: We argue that fast decay of neural activity and depressed states following photic response are likely due to homeostatic mechanisms triggered by excessive neural activity. An improved understanding of the interplay between elevated and depressed excitability states might suggest tailored epilepsy therapies. [ABSTRACT FROM AUTHOR]

Measurement of insomnia is currently generally carried out by medical practitioners by looking at the patient's condition accompanied by symptoms that refer to insomnia. In contrast, minimal quantitative measurements were found. This study proposes an alternative measurement with the acquisition of brainwave activity through electroencephalogram (EEG) in identifying sleep disorders. Insomnia is a common sleep disorder that can make it difficult to fall asleep difficult to stay asleep, or cause waking up too early and not being able to go back to sleep. Insomnia not only weakens energy levels and moods, but also a person's health, performance, and quality of life. This sleep disorder appears due to several factors, such as anxiety, stress, depression, bipolar disorder, or trauma. Photic stimulation is given as an attempt to find a person's body's response to light. Late adolescents with insomnia symptoms with an age range of 17-25 years were included as respondents, had previously been given a simulation test related to the treatment of sleep disorders, and identified severe, moderate, and mild insomnia. Acquisition using Narosky Mindwave Mobile 2 with the electrode in forehead position, Fp1. This study compares several types of insomnia data acquisition from previous studies and obtains patterns of insomniacs based on photic stimulation. [ABSTRACT FROM AUTHOR]

Self-care and improving one's well-being has been growing rapidly in recent years for manifold reasons (e.g. higher workload, corona pandemic). Consumer-grade noninvasive stimulation devices are therefore on the rise to counteract the occurrence of mood disorders and burn-out symptoms. Here, we aim at investigating the impact of dynamically varying auditory-visual stimulation patterns on neural entrainment patterns and resonance phenomena. Twenty-two healthy volunteers (11 female, 25.4±5.1 years, one dropout, seven in control group) participated in the study. EEG data (64 channel; equidistant layout) were acquired preand during stimulation for each volunteer. Visual and auditory stimuli were presented via a headset (ATUM, Neuro- Bright; https://www.neurobright.co.uk/). Presentation patterns (frequency, intensity, spatial distribution) varied within a presentation session but were kept constant across all volunteers. Stimulus intensity was adjusted to individual comfort levels. Individual alpha peak frequencies (iAPF) were calculated via the power spectral density with 50% overlapping 10s epochs from pre-stimulation segments. For both, the study and the control group, a time-frequency representation was calculated for the pre- and during-stimulation segments. From this, power values were determined for different frequency-bands (iAPF, stimulation frequencies and second harmonics of the latter). Statistical analyses focused on contrasting the power values between pre- and during stimulation. Mean iAPF values were 10.25±0.99Hz for the study and 10.63±1.21Hz for the control group respectively. Both, power values at the stimulation frequencies and their second harmonics differed significantly between pre- and during stimulation (pstim=0.001; pharm=0.001) in the study group. No such difference was found for the control group (pstim=0.352; pharm=0.237). Further, neither the study nor the control group showed significant iAPF power differences (pstudy=0.035; pcontrol=0.352; alpha*=0.008). Our results suggest that lightweight, portable auditory-visual presentation devices represent an effective tool for generating entrainment and resonance effects at home. Further analyses will focus on the investigation of individual differences driving such modulatory effects. [ABSTRACT FROM AUTHOR]

Children and adolescents are the largest at-risk group for the appearance of reflex seizures or epilepsy syndromes with a photoparoxysmal response. The aim of this study was to present an overview of the literature regarding photo-dependent reflex seizures. Epilepsy with seizures provoked by intermittent light stimulation is a distinct group of epilepsies; therefore, we focused on reflex seizures provoked by different factors whose common feature is the patient's response to intermittent photic stimulation. A qualitative search of PubMed/MEDLINE, Scopus, EBSCO, and Cochrane Library electronic databases for selected terms was carried out for scientific articles published up to May 2020 outlining the outcomes of control, observational, and case studies. This scoping review was developed and followed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews. The review of the qualitative evidence for the synthesis of photosensitive epilepsy allowed us to distinguish the following categories: light-induced seizures and light-deprived seizures. Differentiating between intermittent photic stimulation-related epilepsy syndromes and seizures is essential in order to determine the length of appropriate treatment. Photo-dependent reflex seizures make up the majority of this type of disorder among reflex seizures. Since there are many seizures provoking factors in the world around us, it is important to distinguish amongst them in order to be able to protect the patient exposed to this factor. It is recommended that the photostimulation procedure be performed during a routine electroencephalogram study. [ABSTRACT FROM AUTHOR]

Objectives The present study aimed to compare the effectiveness of different provocation tests used for the study of the 'susceptibility to seizure' by quantitative electroencephalography (EEG) analysis. Methods Eight subjects with a history of a seizure-like disturbed consciousness participated in this preliminary study. A routine EEG was carried out with photic stimulation (eyes closed and after eyes open) at the beginning of the investigation. Some days later, a sleep-deprived EEG was recorded with the same protocol. Selected epochs (in eyes closed condition) after the stimulations were analysed with Point(wise) Correlation Dimension (PD2i) and Synchronization Likelihood (SL) methods. The results were compared to those obtained by similar analysis of the resting state (control) epochs with Wilcoxon Signed Rank Test (p ≤ 0.05). Results In our study, significantly lower grand mean PD2i and higher delta SL values were found in sleep-deprived state after stimulation with eyes closed compared to the control. Our results indicated a lower-dimensional, hypersynchronous state of the brain as a consequence of these combined provocations. Discussion This may correspond to a possible 'preictal' state of the brain. Accordingly, it is suggested that photic stimulation together with sleep deprivation seems to be more effective in provocation – especially when the stimulation was made with eyes closed. [ABSTRACT FROM AUTHOR]

Studies on brain biometrics have shown that electroencephalogram (EEG) signals encourage more secure authentication. The uniqueness, persistence, universality and robustness of EEG signals against fraud attacks offer potential for highly secure biometric systems. However, more studies are needed to improve collectibility, stability, performance, and acceptability of brain biometrics. EEG signals of healthy subjects were generally used in previous studies. However, adequate studies have not been conducted on subjects who are not mentally healthy. Moreover, EEG signals were usually recorded from healthy subjects at resting, thinking, visual stimulation, and imagery states. In this study, unlike other studies, photic stimuli with EEG data were used for the first time in order to identify both subjects with attention deficit hyperactivity disorder (ADHD) and healthy subjects. In the proposed method, power densities of 1–49 Hz frequencies of EEG segments were obtained by applying periodogram power spectral density estimation method using Kaiser Window to raw EEG data. These values were used for training of 1D Convolutional Neural Network deep learning algorithms. Classification success of the proposed method was measured as 97.17%. These results proved that EEG data obtained from subjects by applying photic stimuli can be used in EEG-based identification systems. [ABSTRACT FROM AUTHOR]

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Background: Studies on mice models of Alzheimer's disease (AD) have suggested potential therapeutic benefits of intermittent photic stimulation at 40 Hz.Objective: We examined the physiological response of 40 Hz intermittent photic stimulation (IPS) on routine EEG in a large retrospective cohort to investigate the effects of age on induced gamma oscillations by intermittent photic stimulation. Since most AD patients are elderly, it is important for future research to know if age affects photic stimulation.Methods: Retrospective data from 1,464 subjects aged 0- 91. We performed frequency analysis and automatic peak detection and used regression analysis to investigate the effects of age and sex on peak frequencies and amplitude changes. To investigate the spread of the induced gamma oscillations, we assessed averaged topographies of 40 Hz band power.Results: There was a statistically significant but very minor effect of age on amplitude change (- 0.002 normalized power per year, p < 0.0001) but not for sex (p = 0.728). Detection probability of induced peaks was significantly predicted by both age (OR = 0.988, CI 95 % [0.984, 0.993], p < 0.00001) and sex (OR = 0.625, CI 95 % [0.496, 0.787>], p < 0.0001). The induced 40 Hz gamma entrainment is spatially confined to the occipital area.Conclusion: There is a significant effect of age on induced gamma activity, but advanced age does not fundamentally change the behavior of the response in either magnitude or spatial distribution. This fact is important regarding future research into the possible therapeutic effects of photic stimulation in patients with AD. [ABSTRACT FROM AUTHOR]

Copyright of Zeitschrift für Epileptologie is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aims To assess inhibitory processes and the ongoing event-related potential (ERP) activity of offspring of alcoholics (OA) during a Go/No-Go task, with the purpose of characterizing possible psychophysiological endophenotypes for alcohol-dependent vulnerability. Short summary EEG recordings and ERP measurements of young adults with positive and negative family history of alcoholism where obtained while they performed a Go/No-Go task to assess inhibitory processes. Offspring of alcoholics showed a different ERP pattern compared to the control group and exerted greater effort than the control group. Methods ERP measurements were obtained by electroencephalogram (EEG) recordings of 65 participants divided into two groups: one group of 30 subjects with positive family history of alcoholism and a control group of 35 subjects with negative family history of alcoholism. They performed a Go/No-Go task, where each individual was required to classify visual stimuli by colour (Go) and inhibit their response to a No-Go signal. Results OA have higher P3 amplitudes during the Go condition in all of the regions analysed and higher No-Go P3 amplitudes than control subjects in the frontal region. Unlike controls, OA have no differences between the P3 amplitudes across conditions. Conclusions The absence of differences between the P3 Go and No-Go observed in the OA group can be interpreted as a possible alteration related with inhibition, in a way that they may need to recruit similar resources for inhibitory and classificational processes for both conditions. Therefore, the P3 component may be considered as a useful endophenotype and a vulnerability marker to develop addictive behaviour. [ABSTRACT FROM AUTHOR]

Objective: The objective was to identify unique features of the photoparoxysmal response seen in patients with neuronal ceroid lipofuscinosis type 2 as compared to patients with a photoparoxysmal response associated with other epilepsy syndromes. Methods: Electroencephalograms from patients with neuronal ceroid lipofuscinosis type 2 seen at the authors’ institution in the past 10 years as well as electroencephalograms (EEGs) reported to have a photoparoxysmal response during a single year were reviewed. Results: A photoparoxysmal response was seen in 60% of the patients with neuronal ceroid lipofuscinosis type 2. This was most commonly seen with low frequency intermittent photic stimulation (76%) which often occurred in a time-locked fashion (63%) and was seen on the patient’s initial EEG (78%). A unique pattern the authors called “sentinel” discharge was identified in 30% of EEGs in patients with neuronal ceroid lipofuscinosis. Conclusions: Photoparoxysmal responses in patients with neuronal ceroid lipofuscinosis type 2 have features which are distinguishing from photoparoxysmal responses seen in other epilepsies. [ABSTRACT FROM AUTHOR]

Intermittent photic stimulation (IPS) is an activation procedure routinely performed during EEG. The EEG response may consist in physiological photic driving (PPD) or in photoparoxysmal response (PPR). Sometimes, the distinction between PPR and PPD can be challenging, especially in case of PPR limited to posterior regions (Waltz type 1 or 2). A commercially available device, namely Zeiss Clarlet F133 lenses (ZEISS lenses), can suppress PPR, while its influence on PPD is still unknown. This study aims to test the effect of ZEISS lenses on PPD at different flash frequencies. We prospectively collected all consecutive EEGs showing PPD to IPS, performed both with eyes open and closed at stimulation frequencies between 3 and 24 Hz. When PPD was present, IPS with ZEISS lenses was performed. We analyzed the presence of PPD without and with lenses by means of McNemar's test We included 97 EEGs showing PPD. This response was more commonly obtained at flash frequencies between 6 and 12 Hz. The use of ZEISS lenses significantly decreased the proportion of subjects showing PPD at each frequency (p < 0.001 for all comparisons). ZEISS lenses significantly reduce the proportion of subjects showing PPD at all stimulus frequencies, regardless of eye opening or closure. Physicians should consider that ZEISS lenses do not allow distinction between PPD and PPR. The effect of ZEISS lenses on PPR and on PPD suppression suggests that these two phenomena derive from similar mechanisms involving the entrainment of neural oscillators within the visual cortex. [ABSTRACT FROM AUTHOR]

The EEG is an invaluable tool in the diagnosis of epilepsy which guides clinical management. It helps to determine if attacks are of epileptic origin, allows the estimation of the recurrence risk after a first seizure, aids in the diagnosis of the epilepsy syndrome and represents the gold standard in the presurgical evaluation of epilepsy. The EEG can also detect subclinical seizures as a cause of coma. In this review we discuss the sensitivity and specificity of the EEG, present the EEG findings and their significance in different epilepsy syndromes including focal and generalized epilepsies and describe the application of activation procedures. [ABSTRACT FROM AUTHOR]

Background Anesthetic depth is an important parameter to monitor during surgery, yet remains difficult to quantify, particularly in young children where developmental changes influence the electroencephalogram. A more fundamental physiological response to stimulation is the increase in cerebral blood flow secondary to increased metabolic demand, referred to as flow-metabolism coupling ( FMC) and measurable using near-infrared spectroscopy ( NIRS). Little is known about the effect of anesthesia on FMC; therefore, we studied visually evoked hemodynamic responses ( VEHRs) using NIRS in children undergoing general anesthesia for minor surgical procedures. Method We recruited 23 children (aged 2-5 years), undergoing surgery requiring general anesthesia. VEHRs were measured for 30 min using NIRS, including 5 min of baseline recording after anesthetic induction. Parameters recorded using NIRS included the concentrations of oxygenated (oxy), deoxygenated (deoxy), and total hemoglobin (Hb), which were separated into epochs for evoked response analysis after filtration of motion artifact and baseline drift. Goodness-of-fit statistics and classification rules were used to determine the existence of evoked responses, and a modified Gaussian equation was used to model each evoked response. Results Near-infrared spectroscopy data were recorded in 20/23 children, of whom nine showed a VEHR. No responses were seen in the baseline control data. When examining the relationship between VEHR and anesthetic agents, we noted that for 8/10 patients in whom preoperative or intraoperative fentanyl were administered and VEHRs were absent. Conclusion We have shown that VEHRs can be detected using NIRS in some anesthetized children. Administration of fentanyl was associated with an absence of VEHRs. The mechanism underlying this association is unclear. [ABSTRACT FROM AUTHOR]

The dynamics of human electroencephalography (EEG) have been proved to be related to cognitive activities. This study separately assessed the two EEG components, amplitude and rhythm, aiming to capture their individual contributions to cognitive functions. We extracted the local peaks of EEGs under rest or photic stimulation and calculated the symbolic dynamics of their voltages (amplitude) and interpeak intervals (instantaneous frequency), individually. The sample consisted of 89 geriatric outpatients in three patient groups: 38 fresh cases of vascular dementia (VD), 22 fresh cases of Alzheimer's disease (AD) and 29 controls. Both sample entropy and number of forbidden words revealed significantly less regular symbolic dynamics in the whole EEG tracings of the VD than the AD and control groups. We found consistent results between groups with the symbolic dynamics in the local-peak voltage sequence rather than the interpeak interval sequence. Photic stimulation amplified the differences between groups. These results suggest that the EEG dynamics which relates to either cognitive functions or the underlying pathologies of dementia are embedded within the dynamics of the amount of but not the interval between each synchronized firing of adjacent cerebral neurons. [ABSTRACT FROM AUTHOR]

Both symptomatic and genetic, cases with hyperekplexia or startle seizures induced by acoustic stimuli, are previously reported. By contrast, startle response induced by visual stimuli is rare. While visual stimuli are more commonly associated with startle seizures, here we present an 11-year-old girl with epilepsy, motor-mental retardation, and spastic tetraparesis, who had repetitive startle responses by photic stimulation during the electroencephalogram recording, without any spike-and-wave discharges associated with the startles. We report this unique case with startle responses induced both by acoustic and photic stimuli and review the literature related to this exceptionally rare combination of symptoms. [ABSTRACT FROM AUTHOR]

Autosomal dominant cortical tremor, myoclonus, and epilepsy (ADCME) is an extremely rare syndrome characterized by familial occurrence of postural and action-induced tremors of the hands but showing electrophysiologic findings of cortical reflex myoclonus. Patients also have cognitive decline and tonic-clonic seizures, often precipitated by sleep deprivation or photic stimulation. We describe probably the first family from India of this ill-defined syndrome. [ABSTRACT FROM AUTHOR]

The model most used to study synaptic plasticity, long-term potentiation ( LTP), typically employs electrical stimulation of afferent fibers to induce changes in synaptic strength. It would be beneficial for understanding the behavioral relevance of LTP if a model could be developed that used more naturalistic stimuli. Recent evidence suggests that the adult visual cortex, previously thought to have lost most of its plasticity once past the critical period, is in fact capable of LTP-like changes in synaptic strength in response to sensory manipulations alone. In a preliminary study, we used a photic tetanus ( PT; flashing checkerboard stimulus) to induce an enhancement of the visual-evoked potential ( VEP) in the primary visual cortex of anesthetised adult rats. In the present study, we sought to compare the mechanisms of this novel sensory LTP with those of traditional electrical LTP. Unexpectedly, we found that sensory LTP was not induced as reliably as we had observed previously, as manipulations of several parameters failed to lead to significant potentiation of the VEP. However, we did observe a significant increase in visual cortex glutamate receptor expression on the surface of isolated synapses following the PT. Both AMPA receptor expression and N-methyl- d-aspartate ( NMDA) receptor subunit expression were increased, specifically in extrasynaptic regions of the membrane, in PT animals. These results provide biochemical confirmation of the lack of change in the VEP in response to PT, but suggest that PT may prime synapses for strengthening upon appropriate subsequent activation, through the trafficking of glutamate receptors to the cell surface. [ABSTRACT FROM AUTHOR]

Electroencephalogram (EEG) reactivity to eyes opening and 12-Hz photic stimulation was investigated in 14 healthy elderly subjects, 21 parkinsonian patients (PD), 7 demented parkinsonian patients (PDD), and 10 patients with Lewy body dementia (LBD) using global field synchronization (GFS). During eyes closed Theta GFS was increased in Parkinson's disease and patients and alpha1 GFS was decreased in LBD subjects. During 12-Hz intermittent photic stimulation (IPS), reactivity of posterior electrodes was decreased in PD and LBD patients. No reactivity was observed in PDD. Results are consistent with a graded posterior cortical disconnection in parkinsonian syndromes and with a model of dopamine-modulated thalamocortical interplay in visual processing. [ABSTRACT FROM AUTHOR]

Intermittent photic stimulation (IPS) shortens the cortical silent period (CSP) elicited by transcranial magnetic stimulation (TMS) over the primary motor hand area (M1HAND). This response is absent in healthy individuals with a photoparoxysmal response (PPR). Here we combined TMS of the M1HAND with IPS to examine whether patients with idiopathic generalized epilepsy (IGE) exhibit an abnormal cortical response pattern to IPS. In 13 PPR-positive and 12 PPR-negative patients with IGE and in 13 PPR-negative healthy controls, we used focal TMS to the M1HAND to study how cortical excitability is changed by concurrent IPS at 50 Hz. IPS at 50 Hz reduced the duration of the CSP in healthy PPR-negative individuals, whereas IPS had no effect on the CSP in PPR-positive and PPR-negative patients with generalized epilepsy. The failure of IPS to shorten the CSP was independent of antiepileptic medication. Single-pulse or paired-pulse TMS only without concurrent IPS showed a higher motor threshold in PPR-positive patients with epilepsy, presumably caused by antiepileptic medication. No additional differences in cortical excitability were found among groups. Because the CSP is mediated by intracortical GABAergic mechanisms, our results indicate that IGEs are associated with an altered responsiveness of GABAergic inhibitory circuits in the M1HAND. This electrophysiological trait is independent of photosensitivity. Excitability changes at the cortical or thalamic level may mediate this abnormal cortical response pattern in patients with IGE. [ABSTRACT FROM AUTHOR]

To understand the regulatory mechanism of the secretory rhythm of GH and the involvement of melatonin (MEL) in GH regulation in cattle, daytime and nighttime profiles of GH secretion and the effect of a photic stimulation on nocturnal GH and MEL secretion were investigated in Holstein steers. Steers were kept under a constant lighting condition of 12 h of light (LIGHT; 500 lx, 0600 to 1800 h):12 h of dark (DARK; 10 lx, 1800 to 0600 h). In Exp. 1, blood was taken for 4 h at 15-mm intervals during LIGHT (1100 to 1500 h) and DARK (2300 to 0300 h), respectively. The sampling was also performed from 0500 to 0900 h, with the usual light transition (light onset at 0600 h; morning sampling). In Exp. 2, steers were exposed to light (500 lx) for 1 h from 0000 to 0100 h. Plasma GH and MEL concentrations were determined by RIA and enzyme immunoassay, respectively. Both GH (P <0.05) and MEL (P < 0.01) concentrations in plasma for 4 h during DARK were greater than those during LIGHT. On the other hand, although MEL concentrations were decreased after the light onset at 0600 during the morning, GH release was not altered. Increased GH secretion during DARK was suppressed (P < 0.01) by the 1 h of light exposure, as were MEL concentrations (P < 0.05). Pineal MEL, which was affected by the photic condition, may play an important role in the secretory rhythm of GH secretion in cattle. [ABSTRACT FROM AUTHOR]

We tested whether evening exposure to unilateral photic stimulation has repercussions on interhemispheric EEG asymmetries during wakefulness and later sleep. Because tight exerts an alerting response in humans, which correlates with a decrease in waking EEG thetalalpha-activity and a reduction in sleep EEG delta activity, we hypothesized that EEG activity in these frequency bands show interhemispheric asymmetries after unilateral bright light (1,500 lux) exposure. A 2-h hemi-field light exposure acutely suppressed occipital EEG alpha activity in the ipsilateral hemisphere activated by light. Subjects felt more alert during bright light than dim light, an effect that was significantly more pronounced during activation of the right than the left visual cortex. During subsequent sleep, occipital EEG activity in the delta and theta range was significantly reduced after activation of the right visual cortex but not after stimulation of the left visual cortex. Furthermore, hemivisual field light exposure was able to shift the left predominance in occipital spindle EEG activity toward the stimulated hemisphere. Time course analysis revealed that this spindle shift remained significant during the first two sleep cycles. Our results reflect rather a hemispheric asymmetry in the alerting action of light than a use-dependent recovery function of sleep in response to the visual stimulation during prior waking. However, the observed shift in the spindle hemispheric dominance in the occipital cortex may still represent subtle local use-dependent recovery functions during sleep in a frequency range different from the delta range. [ABSTRACT FROM AUTHOR]

Copyright of HNO is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Discusses the use of auditory and visual stimulation to improve cognitive ability in learning-disabled children. Wechsler Intelligence Scale for Children, Third Edition Symbol Search, Coding, Arithmetic, and Digit Span; Quasi-experimental study design.

To investigate inter- and intra-hemispheric electroencephalography (EEG) coherence at rest and during photic stimulation of patients with Alzheimer's disease (AD). Thirty-five patients (12 males, 23 females; 52–64 y) and 33 sex- and age-matched controls (12 males, 21 females; 56–65 y) were recruited in the present study. EEG signals from C3–C4, P3–P4, T5–T6 and O1–O2 electrode pairs resulted from the inter-hemispheric action, and EEG signals from C3–P3, C4–P4, P3–O1, P4–O2, C3–O1, C4–O2, T5–O1 and T6-O2 electrode pairs resulted from the intra-hemispheric action. The influence of inter-and intra-hemispheric coherence on EEG activity with eyes closed was examined, using fast Fourier transformation from the 16 sampled channels. The frequencies of photic stimulation were fixed at 5, 10 and 15 Hz, respectively. The general decrease of AD patients in inter- and intra-hemispheric EEG coherence was more significant than that of the normal controls at the resting EEG, with most striking decrease observed in the alpha-1 (8.0–9.0 Hz) and alpha-2 (9.5–12.5 Hz) bands. During photic stimulation, inter- and intra-hemispheric EEG coherences of the AD patients having lower values in the alpha (9.5–10.5 Hz) band than those of the control group. It suggests that under stimulated and non-stimulated conditions, AD patients had impaired inter- and intra-hemispheric functional connections, indicating failure of brain activation in alpha-related frequency. [ABSTRACT FROM AUTHOR]

Purpose: Pharmacotherapy for photosensitive epilepsy is not always effective and is associated with well-recognized toxicities. Nonpharmacologic approaches to the management of photosensitive epilepsy have included the use of sunglasses of various types. Blue lenses have been shown to suppress the photoparoxysmal response more effectively than lenses of other colors with similar overall transmittances. Recently, cross-polarized glasses have shown promise. The axes of polarization of the two lenses of such glasses are perpendicular to one another. We tested the effect of combining the use of blue and cross-polarized lenses in three patients with photosensitive epilepsy. Methods: We recorded the EEG response to photic stimulation, television screens, and computer monitors in three patients with photosensitive epilepsy. If photoparoxysmal responses were provoked in any of these scenarios, testing was repeated with the patient wearing nonpolarized, parallel-polarized, and blue cross-polarized sunglasses. Results: One of our patients had clinical seizures that were inadequately suppressed with moderate doses of valproate (VPA) but completely suppressed with blue cross-polarized lenses. The second patient's photoparoxysmal response was suppressed by both parallel-polarized and blue cross-polarized glasses, whereas the third patient's photoparoxysmal response was not suppressed by either. Conclusions: These preliminary data suggest that blue cross-polarized lenses may be useful in the treatment of photosensitive epilepsies and that their efficacy can be predicted in the EEG laboratory. [ABSTRACT FROM AUTHOR]

Cortical visual disturbances can occur after traumatic or ischemic brain lesion. Patients mostly suffer from hemianopia. Different treatment approaches in patients with hemianopia are being debated with respect to their effectiveness. For more severely disabled patients with cortical blindness or residual rudimentary vision (RRV) no systematic therapeutic approaches have been reported. In a case study the positive effects of a recently developed repetitive photic stimulation therapy in a patient with RRV after a bioccipital ischemic infarction are presented. The application of this new therapy over several months, supported by treatment with amphetamines led to a statistically significant improvement of different visual functions and a reoccurrence of visual abilities important in daily life. The pathophysiological basis and possible neurorehabilitative consequences that arise from these results are discussed with respect to similar findings in animal experiments. [ABSTRACT FROM AUTHOR]

Introduction. This report describes an approach for using repetitive visual stimulation in the context of electroencephalographic (EEG) neurofeedback protocols. The EEG response to repetitive stimulation can be described as a series of successive evoked potentials (EPs), giving rise to a periodic response in the cortex, the steady-state visual evoked potential (SSVEP). Experimental data and signal analyses are presented to support this view. This approach is useful because evoked potential signals reflect sensory and perceptual processes, are sensitive to short-term shifts in attention, and also show important differences between normal and ADD/ADHD groups for example. Methods can be developed to provide real-time measurement and feedback of important variables related to the evoked response. Method. Computerized averaged EP data are compared with filtered EEG “photic driving” responses measured in real time. Synchronous comb-filtering is used to extract real-time SSVEP data which are plotted along with conventional EPs and EEGs. Results are plotted as a time-series and short-term variations are visible. Results. Results of pilot studies are shown, illustrating the ability to record real-time SSVEP's, and to provide information suitable for neurofeedback. The correspondence with averaged evoked potential traces is shown. These data support the concept that EEG responses to repetitive light flashes may be described as a superposition of successive evoked responses, and do not have to appeal to an “entrainment” model. Shortterm variations in signal amplitude are shown to be sensitive to attentive state, and to reveal moment-to-moment changes in brain responsiveness. Discussion. A basic understanding of the brain's response to repetitive stimuli can be used to develop a variety of feedback methods. Some of these are identified. The concept of entrainment is discussed and it is shown that neurofeedback with repetitive photic stimulation may be approached without appealing to the notion of a nonlinear response to repetitive stimulation. In our studies the EEG reveals only the expected periodic evoked responses, indicating that the brain is following the stimulus, but not that any lasting or “entrained” frequencies are introduced. Methods that do not rely on the concept of entrainment, but that depend solely on monitoring and feedback of the brain evoked response, provide promising avenues for neurofeedback. Conclusions. This study provides experimental data and a supporting rationale for the use of photic stimulation in EEG neurofeedback. Our approach is based upon an understanding and use of the fact that the EEG response is comprised of a succession of sensory evoked potentials. This is in contrast to methods and models based upon the concept of nonlinear entrainment. A variety of methods for creating neurofeedback protocols are presented and discussed. [ABSTRACT FROM PUBLISHER]

This study examined the effects of the anticholinergic drug, scopolamine (0.25 mg) in 16 right-handed healthy volunteers. EEGs were recorded before and 60 min after intramuscular administration, and spectral analysis was performed on EEGs recorded at rest and during photic stimulation. Each subject was also evaluated by the Wechsler Memory Scale (WMS; form 1 or 2) before and 90 min after drug administration. In the resting EEG, the scopolamine administration resulted in a significant increase in the absolute power on the delta band (2.0– 3.8 Hz) and in the relative power on the delta and theta-1 bands (4.0–5.8 Hz) mainly over the central and parieto-occipital regions. In contrast, scopolamine significantly decreased the relative alpha-2 band (9.2–12.8 Hz) power mainly over the frontal regions and the absolute alpha-2 band power at most of the recording sites. The analysis of stimulus data showed that scopolamine significantly decreased fundamental photic driving responses elicited by photic stimulation at 15 Hz, with significant effects confined to the occipital regions. These EEG changes occurred in association with a significant reduction in total WMS scores as well as in scores of logical and visual memory subtests. These findings suggest that, in addition to cognitive impairments, central cholinergic dysfunction can cause EEG changes under both nonstimulus and stimulus conditions. [ABSTRACT FROM AUTHOR]

EEG coherence provides a measure of functional correlations between two EEG signals. The present study was conducted to examine intrahemispheric EEG coherence at rest and during photic stimulation (PS) in 18 drug-naive patients with paranoid schizophrenia and 30 control subjects. Compared with the controls, the schizophrenic patients had significantly higher intrahemispheric coherence of the resting EEG for the delta band, although no significant group differences were found for other frequency bands. EEG analysis during PS showed that the patients also had significantly higher EEG coherence over the left posterior regions. In this study, we also examined the changes in intrahemispheric coherence from rest to the stimulus condition (i.e., PS-related coherence reactivity); the patients were found to show significantly smaller changes, with significant group differences being also confined to the posterior regions in the left hemisphere. These findings provide evidence that schizophrenic patients have abnormal EEG coherence in both resting and stimulus conditions and suggest more diffuse, undifferentiated functional organization within hemispheres. In addition, diminished coherence reactivity suggests a failure of PS-related functional reorganization in schizophrenia. [ABSTRACT FROM AUTHOR]

In the present study, quantitative EEG analysis was performed at rest and during 10 Hz photic stimulation in 14 drug-naive patients with first-episode paranoid schizophrenia and 20 sex- and age-matched control subjects. Compared with the normal controls, the patients had significantly lower alpha-2 band amplitude in the resting EEG over all recording regions. No significant group differences were found in other frequency bands. In addition, EEG analysis during photic stimulation demonstrated that the patients had a rather uniform topographic profile in EEG amplitude for the alpha band, with significant group differences being confined to the posterior regions in the left hemisphere. There were no significant group differences in the amplitude for the frequency bands harmonically related to the stimulus frequency. These findings provide further evidence that schizophrenic patients have abnormal EEG activity in both non-stimulus and stimulus conditions, and suggest a dysfunction in the mechanisms underlying EEG alpha generation in schizophrenia. [ABSTRACT FROM AUTHOR]

Individuals with mild cognitive impairment (MCI) are at high risk of developing Alzheimer's disease (AD). Repetitive photic stimulation (PS) is commonly used in routine electroencephalogram (EEG) examinations for rapid assessment of perceptual functioning. This study aimed to evaluate neural oscillatory responses and nonlinear brain dynamics under the effects of PS in patients with mild AD, moderate AD, severe AD, and MCI, as well as healthy elderly controls (HC). EEG power ratios during PS were estimated as an index of oscillatory responses. Multiscale sample entropy (MSE) was estimated as an index of brain dynamics before, during, and after PS. During PS, EEG harmonic responses were lower and MSE values were higher in the AD subgroups than in HC and MCI groups. PS-induced changes in EEG complexity were less pronounced in the AD subgroups than in HC and MCI groups. Brain dynamics revealed a "transitional change" between MCI and Mild AD. Our findings suggest a deficiency in brain adaptability in AD patients, which hinders their ability to adapt to repetitive perceptual stimulation. This study highlights the importance of combining spectral and nonlinear dynamical analysis when seeking to unravel perceptual functioning and brain adaptability in the various stages of neurodegenerative diseases. [ABSTRACT FROM AUTHOR]

Helen Budzynski, widow and collaborator of Thomas Budzynski, describes his life and work, from his early involvement with the SR-71 Blackbird, through his doctoral dissertation research on the use of feedback to induce muscle relaxation, to the first commercial production of a muscle biofeedback device, the development of the Twilight Learning neurofeedback protocol, and his research on the use of sound and light stimulation to modify brain processes. [ABSTRACT FROM AUTHOR]