Decreased resting-state alpha peak frequency in children and adolescents with fetal alcohol spectrum disorders or prenatal alcohol exposure

Differences in neurophysiological resting-state alpha spectral events in 4-12-year-old children with prenatal exposure to alcohol relative to typically developing controls

OBJECTIVE

To investigate the effects of age and prenatal alcohol exposure (PAE) on the constituent parameters underlying mean alpha power.

METHODS

Resting-state magnetoencephalography (MEG) alpha events were characterized by measuring event spectral power, number of events per epoch, duration of events, and frequency span within the alpha band (7-13 Hz) in 82 typically developing controls (TDCs) and 53 participants with PAE/FASD. We examined the relationship between these parameters and overall mean alpha power as well as how they differ with age and PAE/FASD.

RESULTS

Age negatively correlated with mean event duration in both groups, (r = -0.29, p < 0.001) with duration reduced in older participants. Age negatively correlated with mean alpha power's association with mean event duration in PAE/FASD (r = -0.38, p < 0.05) and positively correlated with mean alpha power's association with mean event frequency span in both groups (r = 0.22, p < 0.05). The correlation between mean alpha power and mean event duration (p = 0.038) was stronger in TDCs. Despite the group difference, longer event durations led to more mean alpha power in both groups. Mean alpha power negatively correlated with mean event frequency span in both groups but the negative correlation was stronger in the TDC group (p = 0.036) CONCLUSION: The differences found in alpha events with age and PAE may provide valuable insights into the physiological correlates of attention and highlight the potential of alpha oscillations as biomarkers for understanding attention-related deficits in children with prenatal alcohol exposure.

Aging amplifies sex differences in low alpha and low beta EEG oscillations

Biological sex profoundly shapes brain function, yet its precise influence on neural oscillations was poorly understood. Despite decades of research, studies investigating sex-based variations in electroencephalographic (EEG) signals have yielded inconsistent findings that obstructs what may be a potentially crucial source of inter-individual variability in brain function. To address this, we analyzed five publicly available resting-state datasets, comprising EEG data (n = 445) and iEEG data (n = 103). Three age ranges were defined, young adult (YA, 18-30 years), middle-aged adult (MA, 30-55 years) and older adult (OA, 55-80 years). Our results revealed striking age-dependent sex differences: OA group exhibited robust sex differences, with males showing heightened low alpha (8-9 Hz) activity in temporal regions and attenuated low beta (16-20 Hz) oscillations in parietal-occipital areas compared to females. Intriguingly, these sex-specific patterns were absent in YA group, suggesting a complex interplay between sex and aging in shaping brain dynamics. The MA groups fall in between YA and OA group. The increase of low beta band activity in older female adults is strongly associated with hip size and BMI. Furthermore, we identified consistent sex-related activity in the precentral gyrus with the results of scalp EEG, potentially driving the observed scalp EEG differences. This multi-level analysis allowed us to bridge the gap between cortical and scalp-level observations, providing a more comprehensive picture of sex-related neural dynamics. The distinct associations between sex-specific oscillatory patterns and several lifestyle factors demonstrates the complex interplay between sex, age, and neural oscillations, revealing the variability in brain dynamics. Our findings highlight the importance of careful demographic consideration in EEG research design to ensure fairness in capturing the full spectrum of neurophysiological diversity.

Thalamic Nuclear Volumes in Fetal Alcohol Spectrum Disorders: from Adolescence to Middle-Age 20 Years Later

BACKGROUND

Midline orofacial and brain structures, including the multinucleated thalamus, may be differentially sensitive to prenatal alcohol exposure and vulnerable to accelerated aging.

METHODS

Two sets of MRI data separated by 20 years are reported for controls, individuals with fetal alcohol syndrome (FAS), and nondysmorphic individuals with heavy fetal alcohol exposure (FAE). MRI1 included 179 participants with 69 reassessed at MRI2. Segmentation produced estimates of bilateral thalamic volume and 10 bilateral nuclei, which were aggregated into Anterior, Ventral, Posterior, and Medial Volumes. Differences were assessed without and with correction for intracranial volume (ICV).

RESULTS

MRI1 revealed stepwise group differences in ICV, total thalamic volume, and Anterior and Ventral regions uncorrected for ICV, where Controls>FAE>FAS. Corrected for ICV, the smaller volumes endured in the Anterior and Ventral regions, although differences between FAE and FAS groups were attenuated. Nuclei volumes were selectively smaller in the alcohol-exposed groups than controls even after controlling for ICV. Longitudinally, thalamic volumes typically declined over time maintaining the stepwise effects and with little evidence for accelerated decline in the FAE or FAS groups.

CONCLUSIONS

These novel data revealed stable deficits in thalamic nuclei of the groups with heavy fetal alcohol exposure. After 20 years, the deficits endured but without accelerated age-related decline and following the same aging pattern as controls. Despite parallel aging functions in all groups, ICV adjustment yielded volume deficits localized to the anterior and ventral thalamic nuclei, differing from patterns in the remaining thalamic nuclei and cortical brain structures.

Impact of Developmental Alcohol Exposure on the Thalamus

This chapter comprehensively explores the impact of prenatal alcohol (ethanol) exposure (PAE) on the thalamus, integrating findings from animal models and human studies spanning various developmental stages. Animal model investigations, encompassing first and second trimester-equivalent exposures and the critical third trimester, where the brain growth spurt starts, reveal specific alterations in thalamic structures and circuits, emphasizing the specificity of damage to corticothalamic loops. The ventrobasal thalamic nucleus exhibits a unique response to PAE, involving intricate interactions with postnatal neurogenesis and neurotrophin responsiveness. Third trimester-equivalent exposure consistently induces apoptotic neurodegeneration in various thalamic nuclei, highlighting the heightened susceptibility of the visual thalamus, particularly the lateral geniculate nucleus, during critical developmental periods. The nucleus reuniens, vital for cognitive processes, was shown to be significantly affected by alcohol exposure during this period. Investigations into the trigeminal/somatosensory system activity revealed disruptions in glucose utilization and increased neuronal activity in the thalamus. Research on binge-like alcohol exposure during the brain growth spurt demonstrates lasting modifications in action-potential properties and synaptic currents in thalamic neurons projecting to the retrosplenial cortex. Human studies, employing advanced techniques like super-resolution fetal MRI and functional MRI, underscore the PAE-induced structural and functional consequences in the thalamus and its connections, spanning from fetal development to adulthood. The complex effects of PAE on thalamic structure and function vary across developmental stages, emphasizing the importance of considering factors such as age and concurrent exposures. The development of higher-resolution imaging tools is essential for assessing the impact of PAE on the structure and function of individual thalamic nuclei in humans.

Sex-specific Differences in Resting Oscillatory Dynamics in Children with Prenatal Alcohol Exposure

At rest children with prenatal alcohol exposure (PAE) exhibit impaired static and dynamic functional connectivity, along with decreased alpha oscillations. Sex-specific information regarding the impact of PAE on whole-brain resting-state gamma spectral power remains unknown. Eyes-closed and eyes-open MEG resting-state data were examined in 83 children, ages 6-13 years of age. Using a matched design, the sample consisted of 42 typically developing children (TDC) (22 males/20 females) and 41 children with PAE and/or a fetal alcohol spectrum disorders (FASD) diagnosis (21 males/20 females). Whole-brain source resting-state spectral power was examined to determine group and sex specific relationships. Within gamma, we found sex and group specific changes such that female participants with PAE/FASD had increased gamma power when compared to female TDC and male participants with PAE/FASD. These differences were detected in most source regions analyzed during both resting-states, and were observed across the age spectrum examined. Within delta, we found sex and group specific changes such that female participants with PAE/FASD had decreased delta power when compared to female TDC and male participants with PAE/FASD. The reduced delta oscillations in female participants with PAE/FASD were detected in several source regions during eyes-closed rest and were evident at younger ages. These results indicate PAE alters neural oscillations during rest in a sex-specific manner, with females with PAE/FASD showing the largest perturbations. These results further demonstrate PAE has global effects on resting-state spectral power and connectivity, creating long-term consequences by potentially disrupting the excitation/inhibition balance in the brain, interrupting normative neurodevelopment.

Examining the effects of prenatal alcohol exposure on performance of the sustained attention to response task in children with an FASD

Prenatal alcohol exposure (PAE), the leading known cause of childhood developmental disability, has long-lasting effects extending throughout the lifespan. It is well documented that children prenatally exposed to alcohol have difficulties inhibiting behavior and sustaining attention. Thus, the Sustained Attention to Response Task (SART), a Go/No-go paradigm, is especially well suited to assess the behavioral and neural functioning characteristics of children with PAE. In this study, we utilized neuropsychological assessment, parent/guardian questionnaires, and magnetoencephalography during SART random and fixed orders to assess characteristics of children 8-12 years old prenatally exposed to alcohol compared to typically developing children. Compared to neurotypical control children, children with a Fetal Alcohol Spectrum Disorder (FASD) diagnosis had significantly decreased performance on neuropsychological measures, had deficiencies in task-based performance, were rated as having increased Attention-Deficit/Hyperactivity Disorder (ADHD) behaviors and as having lower cognitive functioning by their caretakers, and had decreased peak amplitudes in Broadmann's Area 44 (BA44) during SART. Further, MEG peak amplitude in BA44 was found to be significantly associated with neuropsychological test results, parent/guardian questionnaires, and task-based performance such that decreased amplitude was associated with poorer performance. In exploratory analyses, we also found significant correlations between total cortical volume and MEG peak amplitude indicating that the reduced amplitude is likely related in part to reduced overall brain volume often reported in children with PAE. These findings show that children 8-12 years old with an FASD diagnosis have decreased amplitudes in BA44 during SART random order, and that these deficits are associated with multiple behavioral measures.

Aberrant age-related alterations in spontaneous cortical activity in participants with cerebral palsy

Introduction

Cerebral Palsy (CP) is the most common neurodevelopmental motor disability, resulting in life-long sensory, perception and motor impairments. Moreover, these impairments appear to drastically worsen as the population with CP transitions from adolescents to adulthood, although the underlying neurophysiological mechanisms remain poorly understood.

Methods

We began to address this knowledge gap by utilizing magnetoencephalographic (MEG) brain imaging to study how the amplitude of spontaneous cortical activity (i.e., resting state) is altered during this transition period in a cohort of 38 individuals with spastic diplegic CP (Age range = 9.80-47.50 years, 20 females) and 67 neurotypical controls (NT) (Age range = 9.08-49.40 years, Females = 27). MEG data from a five-minute eyes closed resting-state paradigm were source imaged, and the power within the delta (2-4 Hz), theta (5-7 Hz), alpha (8-12 Hz), beta (15-29 Hz), and gamma (30-59 Hz) frequency bands were computed.

Results

For both groups, the delta and theta spontaneous power decreased in the bilateral temporoparietal and superior parietal regions with age, while alpha, beta, and gamma band spontaneous power increased in temporoparietal, frontoparietal and premotor regions with age. We also found a significant group x age interaction, such that participants with CP demonstrated significantly less age-related increases in the spontaneous beta activity in the bilateral sensorimotor cortices compared to NT controls.

Discussion

Overall, these results demonstrate that the spontaneous neural activity in individuals with CP has an altered trajectory when transitioning from adolescents to adulthood. We suggest that these differences in spontaneous cortical activity may play a critical role in the aberrant motor actions seen in this patient group, and may provide a neurophysiological marker for assessing the effectiveness of current treatment strategies that are directed at improving the mobility and sensorimotor impairments seen in individuals with CP.

Disrupted dynamic functional network connectivity in fetal alcohol spectrum disorders

BACKGROUND

Prenatal alcohol exposure (PAE) can result in harmful and long-lasting neurodevelopmental changes. Children with PAE or a fetal alcohol spectrum disorder (FASD) have decreased white matter volume and resting-state spectral power compared to typically developing controls (TDC) and impaired resting-state static functional connectivity. The impact of PAE on resting-state dynamic functional network connectivity (dFNC) is unknown.

METHODS

Using eyes-closed and eyes-open magnetoencephalography (MEG) resting-state data, global dFNC statistics and meta-states were examined in 89 children aged 6-16 years (51 TDC, 38 with FASD). Source analyzed MEG data were used as input to group spatial independent component analysis to derive functional networks from which the dFNC was calculated.

RESULTS

During eyes-closed, relative to TDC, participants with FASD spent a significantly longer time in state 2, typified by anticorrelation (i.e., decreased connectivity) within and between default mode network (DMN) and visual network (VN), and state 4, typified by stronger internetwork correlation. The FASD group exhibited greater dynamic fluidity and dynamic range (i.e., entered more states, changed from one meta-state to another more often, and traveled greater distances) than TDC. During eyes-open, TDC spent significantly more time in state 1, typified by positive intra- and interdomain connectivity with modest correlation within the frontal network (FN), while participants with FASD spent a larger fraction of time in state 2, typified by anticorrelation within and between DMN and VN and strong correlation within and between FN, attention network, and sensorimotor network.

CONCLUSIONS

There are important resting-state dFNC differences between children with FASD and TDC. Participants with FASD exhibited greater dynamic fluidity and dynamic range and spent more time in states typified by anticorrelation within and between DMN and VN, and more time in a state typified by high internetwork connectivity. Taken together, these network aberrations indicate that prenatal alcohol exposure has a global effect on resting-state connectivity.