Effect of sleep state on the flash visual evoked potential. A case study

Diversity and limitations of electroencephalogram and event-related potential applications in nursing research: A scoping review

AIMS

This scoping review was conducted to provide a comprehensive summary of how electroencephalogram (EEG) and event-related potentials (ERPs) have been used in nursing research, with the goal of mapping the themes and methods of nursing research involving EEGs or ERPs as a measurement tool.

METHODS

The eligibility criteria were determined according to the Population, Concept, and Context principle. A systematic electronic search of articles in the PubMed, Web of Science, Embase, CINAHL, APA PsycInfo, and Scopus databases was carried out for the period from database establishment to November 21, 2022. The included studies were analyzed using descriptive statistics and content analysis.

RESULTS

The review process culminated in 45 articles, evidencing an increasing trend and dispersion characteristics of EEG in nursing research and reflecting five thematic domains of inquiry related to nursing. There was a deficiency of detailed reports of EEG recording and data analysis parameters in nursing research. The common EEG bands in nursing research were Delta, Theta, Alpha, Beta, Gamma. The ERP components used frequently were P3, P2, N1, N2, P1, N170, and feedback-related negativity.

CONCLUSIONS

The wide variety of EEG components used show broad potential for studying nursing questions. In the future, it will be necessary to increase the depth of the research content, the repeatability of the experiment and the standardization of the report. Nursing researchers should give full play to the characteristics of nursing and establish a systematic and complete EEG research system for nursing.

Delayed maturation of P2 flash visual evoked potential (VEP) latency in newborns of gestational diabetic mothers

BACKGROUND

The prevalence of gestational diabetes mellitus (GDM) has rapidly increased, yet few prior studies have investigated parameters of early brain development in infants born to gestational diabetic mothers. The present study assessed visual evoked potentials (VEPs) in healthy infants born to gestational diabetic mothers and matched controls.

METHODS

After exclusions, in this prospective study we examined VEPs in 73 neonates between 37 weeks and 41 weeks gestation at birth (n = 37 infants of gestational diabetic mothers). Stroboscopic flashes were presented through closed eyelids during passive electroencephalography (EEG) recording to derive VEP waveforms during natural sleep.

RESULTS

There was a statistically significant moderate correlation between gestational age at birth and P2 latency of the flash VEP where P2 latency significantly decreased with increasing gestational age (Pearson's R(73) = -0.32, p < .01). There was also a significant moderate correlation between postnatal age (hours of life) and P2 latency of the flash VEP where P2 latency significantly decreased with increasing postnatal age (Pearson's R(73) = -0.23, p < .05). When controlling for gestational age at birth, postnatal age, and sex, there was a significant effect of group (GDM-exposed vs. control) on P2 latency of the flash VEP (p < .05). Infants of gestational diabetic mothers had a significantly longer P2 latency (M: 215.29 ± SD: 2.58 ms) than controls (M: 206.41 ± SD: 2.62 ms).

CONCLUSION

Our findings suggest P2 flash VEP latency is a potential measure of cortical maturation and marker of immature development in infants of gestational diabetic mothers.

Visual evoked potentials are similar in polysomnographically defined quiet and active sleep in healthy newborns

Morphology and late components of evoked potentials change depending on wake-sleep stages in adults. Visual Evoked potentials (VEPs) have been frequently studied in newborns to identify abnormal development of visual pathways; however, large variability has been reported and there is uncertainty as to the effect of sleep stages on VEPs in neonates.

OBJECTIVE

To describe the characteristics of VEPs in one month old, healthy full-term newborns during active sleep (AS) and quiet sleep (QS), defined by simultaneous polysomnography (PSG).

METHODS

VEPs were obtained by monocular LEDs stimulation of each eye during AS and QS, in 20 healthy full-term newborns (gestational age 37-40 weeks) with normal birth weights and normal prenatal Doppler ultrasound indices. Latencies and amplitudes of N2, P2 and N3 components in AS and QS were compared, and their association with absolute power of EEG frequency bands, assessed.

RESULTS

There were no significant differences in VEP morphology, latencies and amplitudes between sleep states. Typical wave forms were obtained in all newborns in AS; however, no VEPs could be identified clearly in 3 newborns in QS; QS VEPs were less reliable than in AS: more averaging was required; correlation was significantly lower between the VEP averages; and a larger number of babies needed more than two averages to obtain replicable responses needed for clinical purposes.

CONCLUSIONS

These results indicate that changes in amplitude and latency of some VEP components observed in NREM and REM sleep in adults are not yet present in one month old newborns probably due to immaturity of cortical and sleep mechanisms. VEPs are more reliable during AS than QS in newborns. Systematic VEP recording during AS, and polysomnographic control to identify this stage, are highly recommended as methods that can increase there liability of neonatal VEPs.

Efeito do estado atencional na detecção automática das respostas auditivas corticais em neonatos

RESUMO Objetivo O objetivo desse estudo foi comparar a latência e amplitude do potencial evocado auditivo cortical P1i entre neonatos em estado de alerta e durante o sono leve. Métodos Vinte e cinco neonatos com emissões otoacústicas evocadas transientes presentes foram testados, por meio do potencial evocado auditivo cortical (PEAC), sendo dez em estado de alerta e 15 durante o sono leve. Para pesquisa dos potenciais corticais, utilizou-se o equipamento Hearlab System, de um canal, no módulo Cortical Tone Evaluation (CTE). O potencial P1i foi pesquisado de forma monoaural, na intensidade de 80 dBnNA, para as frequências de 500, 1000, 2000 e 4000Hz. A detecção do P1i foi feita de maneira automática pelo equipamento. A marcação da latência e amplitude foi realizada por três juízes. Resultados Não houve diferença estatisticamente significativa entre os dois grupos de neonatos para os valores de amplitude e latência, nas quatro frequências testadas. Conclusão Não houve influência do estado comportamental dos neonatos na avaliação do potencial cortical P1i.

The elicitation of steady-state visual evoked potentials during sleep

This study confirmed the hypothesis that it is possible to elicit SSVEPs through closed eyelids during NREM sleep. To test this hypothesis, SSVEP amplitudes were measured in eight subjects across two conditions of stimulation (stimulation on and stimulation off) and three brain states (waking, light sleep, and deep sleep). Results showed a significant interaction between stimulation and brain state. In particular, EEG activity at the frequency of stimulation was higher during both light sleep and deep sleep in the stimulation on condition than in the stimulation off condition. The fact that it is possible to elicit SSVEPs during sleep may provide a new way to study how SSVEPs are generated in the brain-one that might help resolve open questions such as identifying the SSVEP activation sequence or deciding if SSVEPs derive from evoked or oscillatory neural processes.

Habituation of visual evoked responses in neonates and fetuses: a MEG study

In this study we aimed to develop a habituation paradigm that allows the investigation of response decrement and response recovery and examine its applicability for measuring the habituation of the visually evoked responses (VERs) in neonatal and fetal magnetoencephalographic recordings. Two paradigms, one with a long and one with a short inter-train interval (ITI), were developed and tested in separate studies. Both paradigms consisted of a train of four light flashes; each train being followed by a 500Hz burst tone. Healthy pregnant women underwent two prenatal measurements and returned with their babies for a neonatal investigation. The amplitudes of the neonatal VERs in the long-ITI condition showed within-train response decrement. An increased response to the auditory dishabituator was found confirming response recovery. In the short-ITI condition, neonatal amplitude decrement could not be demonstrated while response recovery was present. In both ITI conditions, the response rate of the cortical responses was much lower in the fetuses than in the neonates. Fetal VERs in the long-ITI condition indicate amplitude decline from the first to the second flash with no further decrease. The long-ITI paradigm might be useful to investigate habituation of the VERs in neonates and fetuses, although the latter requires precaution.

Auditory processing during sleep in preterm infants: An event related potential study

Auditory processing during sleep was investigated in premature infants by auditory event related potentials (AERPs). Twenty-six premature infants (mean GA 30 week- range 25-35) admitted to a neonatal intensive care unit were studied, prior to discharge, in active and quiet sleep at a mean post-conceptional age of 35 weeks. Infant state was determined by behavioral observation according to standard criteria. An auditory odd-ball paradigm was used with frequently occurring 'standard' tones at 1000Hz and infrequent 'deviant' tones at 2000Hz. Waveforms were recorded at Fz, Cz, Pz, T3 and T4 scalp locations. Measurements were performed in 18 patients because 8 preterm infants were excluded since they had less than the required artifact-free deviant trials in each sleep state. The responses to standard tones were equally recorded in both active and quiet sleep, but auditory responses to deviant tones consisting of an increased frontal negativity in the time period from 200 to 300ms after the stimulus were recorded only in active sleep. A significant effect of electrode placement, for frontal location by sleep condition and sleep condition by 50ms time windows was shown by repeated measures analyses of variance. The significance of these findings on evoked potential methodology in preterm infants admitted to neonatal intensive care unit is discussed.

Flash visually evoked potentials in the newborn and their maturation during the first six months of life

The aim of this paper has been to obtain normative data for the major components of the visually evoked potentials obtained by flash stimulus (F-PEV) in the newborn, and to analyse the evolution of these responses during the first 24 weeks of life. In order to do so, F-VEP were recorded in 109 normal full-term newborn infants. Fifty-five of these infants were also studied longitudinally at 4, 8, 12 and 24 weeks. We recorded responses in all newborns. A great morphological variability was observed. P2 was the only component present in all of these infants. Early components, which were always present from the fourth week of life on, were recorded in 34% of the newborns. There were significant differences according to waking/sleep state. At 24 weeks the most characteristic response was a triphasic waveform with clear negative-positive-negative components at 67.9, 110 and 158.3 ms. The morphological variability observed in the F-PEV of the newborn and the presence of early components in some cases, suggest differences in the maturation of the specific and unspecific visual system at birth. The study of these responses provides us with information about certain aspects of visual maturation. The relative stability of P2 response of the newborn and of the early negative components later on, made them the most useful components to be used in paediatric clinical work . The latency of P2 in the newborn is the parameter that showed lower variability, and therefore the most suitable one to establish normative data.