Altered functional connectivity during spatial working memory in children with heavy prenatal alcohol exposure

Prenatal alcohol exposure and associations with physical size, dysmorphology and neurodevelopment: a systematic review and meta-analysis

BACKGROUND

Fetal alcohol spectrum disorder (FASD) is a significant public health concern, yet there is no internationally agreed set of diagnostic criteria or summary of underlying evidence to inform diagnostic decision-making. This systematic review assesses associations of prenatal alcohol exposure (PAE) and outcomes of diagnostic assessments, providing an evidence base for the improvement of FASD diagnostic criteria.

METHODS

Six databases were searched (inception-February 2023). Case-controls or cohort studies examining associations between participants with/without PAE or a FASD diagnosis and the domains of physical size, dysmorphology, functional neurodevelopment and/or brain structure/neurology were included. Excluded studies were non-empirical, sample size < 10, PAE determined via biological markers only, or no suitable comparison group. Summary data were extracted and associations between outcomes and standardised levels of PAE or FASD diagnosis determined using random-effects meta-analyses. Certainty of the evidence was assessed using GRADE.

RESULTS

Of the 306 included studies, 106 reported physical size, 43 dysmorphology, 195 functional neurodevelopment and 110 structural/neurological outcomes, with 292 different outcomes examined. There was a dose-response relationship between PAE and head circumference, as well as measures of physical size, particularly at birth. There was also an association between higher PAE levels and characteristic sentinel facial dysmorphology, as well as many of the current functional neurodevelopmental outcomes considered during diagnosis. However, data were often lacking across the full range of exposures. There was a lack of evidence from studies examining PAE to support inclusion of non-sentinel dysmorphic features, social cognition, speech-sound impairments, neurological conditions, seizures, sensory processing or structural brain abnormalities (via clinical MRI) in diagnostic criteria. GRADE ratings ranged from very low to moderate certainty of evidence.

CONCLUSIONS

This comprehensive review provides guidance on which components are most useful to consider in the diagnostic criteria for FASD. It also highlights numerous gaps in the available evidence. Future well-designed pregnancy cohort studies should specifically focus on dose-response relationships between PAE and dysmorphology, neurodevelopment and brain structure/neurological outcomes.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO: CRD42021230522.

Embryonic alcohol exposure alters cholinergic neurotransmission and memory in adult zebrafish

Alcohol is the most consumed addictive substance worldwide that elicits multiple health problems. Consumption of alcoholic beverages by pregnant women is of great concern because pre-natal exposure can trigger fetal alcohol spectrum disorder (FASD). This disorder can significantly change the embryo's normal development, mainly by affecting the central nervous system (CNS), leading to neurobehavioral consequences that persist until adulthood. Among the harmful effects of FASD, the most reported consequences are cognitive and behavioral impairments. Alcohol interferes with multiple pathways in the brain, affecting memory by impairing neurotransmitter systems, increasing the rate of oxidative stress, or even activating neuroinflammation. Here, we aimed to evaluate the deleterious effects of alcohol on the cholinergic signaling and memory in a FASD zebrafish model, using inhibitory avoidance and novel object recognition tests. Four months after the embryonic exposure to ethanol, the behavioral tests indicated that ethanol impairs memory. While both ethanol concentrations tested (0.5 % and 1 %) disrupted memory acquisition in the inhibitory avoidance test, 1 % ethanol impaired memory in the object recognition test. Regarding the cholinergic system, 0.5 % ethanol decreased ChAT and AChE activities, but the relative gene expression did not change. Overall, we demonstrated that FASD model in zebrafish impairs memory in adult individuals, corroborating the memory impairment associated with embryonic exposure to ethanol. In addition, the cholinergic system was also affected, possibly showing a relation with the cognitive impairment observed.

A working memory intervention for children with prenatal alcohol exposure: Pilot study

Cogmed© is a computerized working memory training program designed to improve attention and working memory. We examined the short- and long-term impacts of a 25-session Cogmed© intervention on working memory and other cognitive and learning domains in children with prenatal alcohol exposure (PAE) and typically developing children. Participants included 38 children (4 - 13 years old) from Alberta, Canada in two groups: PAE (n = 20) and typically developing (n = 18). Significant improvements in areas of working memory and attentional control for both the PAE and the typically developing group were reported immediately after intervention completion (short-term impact). The gains on some measures were retained at five-week follow up (long-term impact). Preliminary findings indicate that computerized interventions may positively impact WM and attention control and that these changes may be maintained after a delay period.

Functional connectivity of cognition-related brain networks in adults with fetal alcohol syndrome

BACKGROUND

Fetal alcohol syndrome (FAS) can result in cognitive dysfunction. Cognitive functions affected are subserved by few functional brain networks. Functional connectivity (FC) in these networks can be assessed with resting-state functional MRI (rs-fMRI). Alterations of FC have been reported in children and adolescents prenatally exposed to alcohol. Previous reports varied substantially regarding the exact nature of findings. The purpose of this study was to assess FC of cognition-related networks in young adults with FAS.

METHODS

Cross-sectional rs-fMRI study in participants with FAS (n = 39, age: 20.9 ± 3.4 years) and healthy participants without prenatal alcohol exposure (n = 44, age: 22.2 ± 3.4 years). FC was calculated as correlation between cortical regions in ten cognition-related sub-networks. Subsequent modelling of overall FC was based on linear models comparing FC between FAS and controls. Results were subjected to a hierarchical statistical testing approach, first determining whether there is any alteration of FC in FAS in the full cognitive connectome, subsequently resolving these findings to the level of either FC within each network or between networks based on the Higher Criticism (HC) approach for detecting rare and weak effects in high-dimensional data. Finally, group differences in single connections were assessed using conventional multiple-comparison correction. In an additional exploratory analysis, dynamic FC states were assessed.

RESULTS

Comparing FAS participants with controls, we observed altered FC of cognition-related brain regions globally, within 7 out of 10 networks, and between networks employing the HC statistic. This was most obvious in attention-related network components. Findings also spanned across subcomponents of the fronto-parietal control and default mode networks. None of the single FC alterations within these networks yielded statistical significance in the conventional high-resolution analysis. The exploratory time-resolved FC analysis did not show significant group differences of dynamic FC states.

CONCLUSIONS

FC in cognition-related networks was altered in adults with FAS. Effects were widely distributed across networks, potentially reflecting the diversity of cognitive deficits in FAS. However, no altered single connections could be determined in the most detailed analysis level. Findings were pronounced in networks in line with attentional deficits previously reported.

Spiral drawing deficits in children with prenatal alcohol exposure

AIMS

Empirical investigations reveal that, in comparison to their typically developing peers, children with histories of prenatal alcohol exposure experience deficits in writing but not drawing skills, both of which require fine motor control. This study examines drawing skills in this clinical group by assessing simple free-form spiral drawings with indices of spectral features and structural organization.

METHODS

Children with (n = 15) and without (n = 24) prenatal alcohol exposure used their dominant and nondominant hands to draw a series of spirals using a wireless pen stylus that either provided concurrent visual feedback in the form of a black ink trace or left no visible ink trace of each drawing. Spirals were drawn on a sheet of paper placed on a digitizing table, which facilitated online data acquisition. The data were assessed by power spectral density function analysis and sample entropy analysis.

RESULTS

In comparison to their typically developing peers, children with prenatal alcohol exposure produced spirals with a lower mean frequency and less spectral variability. Spirals in the prenatally exposed group were also lower in complexity and structural organization than in the control group. These results occurred independently of hand dominance or the availability of visual feedback.

CONCLUSIONS

The drawing skills of children with prenatal alcohol exposure have inherent signal characteristics that differ significantly from those produced by typically developing peers. Simple tasks requiring fine motor control may be useful in identifying individuals with fetal alcohol spectrum disorders.

Impaired cognitive control after moderate prenatal alcohol exposure corresponds to altered EEG power during a rodent touchscreen continuous performance task

Although it is well established that alcohol consumption during pregnancy can lead to lifelong difficulties in offspring, Fetal Alcohol Spectrum Disorders (FASD) remain a common neurodevelopmental syndrome. Translational behavioral tools that target similar brain circuits across species can facilitate understanding of these cognitive consequences. Touchscreen behavioral tasks for rodents enable easy integration of dura recordings of electroencephalographic (EEG) activity in awake behaving animals, with clear translational generalizability. Recently, we showed that Prenatal Alcohol Exposure (PAE) impairs cognitive control on the touchscreen 5-Choice Continuous Performance Task (5C-CPT) which requires animals to touch on target trials (hit) and withhold responding on non-target trials (correct rejection). Here, we extended these findings to determine whether dura EEG recordings would detect task-relevant differences in medial prefrontal cortex (mPFC) and posterior parietal cortex (PPC) corresponding with behavioral alterations in PAE animals. Replicating previous findings, PAE mice made more false alarm responses versus controls and had a significantly lower sensitivity index. All mice, regardless of sex or treatment, demonstrated increased frontal theta-band power during correct trials that followed an error (similar to post-error monitoring commonly seen in human participants). All mice showed a significant decrease in parietal beta-band power when performing a correct rejection versus a hit. PAE mice of both sexes showed a significantly larger decrease in parietal beta-band power when successfully rejecting non-target stimuli. These findings suggest that moderate exposure to alcohol during development can have long lasting effects on cognitive control, and task-relevant neural signals may provide a biomarker of impaired function across species.

Evaluation of Brain Alterations and Behavior in Children With Low Levels of Prenatal Alcohol Exposure

IMPORTANCE

High levels of prenatal alcohol exposure (PAE) are associated with widespread behavioral and cognitive problems as well as structural alterations of the brain. However, it remains unclear whether low levels of PAE affect brain structure and function, and prior studies generally have not had well-matched control populations (eg, for sociodemographic variables).

OBJECTIVE

To compare structural brain alterations and behavioral changes in children with lower levels of PAE with those of well-matched controls with no PAE.

DESIGN, SETTING, AND PARTICIPANTS

In this cross-sectional study, participants were selected from the Adolescent Brain Cognitive Development study. Children with PAE were compared with controls matched for age, sex, family income, maternal educational level, and caregiver status. Neither group had prenatal exposure to other adverse substances (eg, tobacco, cannabis, illicit drugs). Data were collected from September 1, 2016, to November 15, 2018, and analyzed from October 14, 2020, to February 14, 2022.

EXPOSURES

Diffusion tensor imaging, resting-state functional magnetic resonance imaging (MRI), and Child Behavior Checklist (CBCL) administration.

MAIN OUTCOMES AND MEASURES

Fractional anisotropy (FA); mean, axial, and radial diffusivity from diffusion tensor imaging; brain functional signal variations from functional MRI; and several scores, including internalizing and externalizing behavior problems, from the CBCL. Spearman correlation coefficients between diffusion tensor imaging and functional MRI measures and the CBCL scores were calculated.

RESULTS

A total of 270 children were included in the analysis (mean [SD] age, 9.86 [0.46] years; 141 female [52.2%] and 129 male [47.8%]), consisting of 135 children with PAE (mean [SD] age, 9.85 [0.65] years; 73 female [54.1%] and 62 male [45.9%]) (mean exposure, 1 drink/wk) and 135 unexposed controls (mean [SD] age, 9.87 [0.04] years; 68 female [50.4%] and 67 male [49.6%]). Children with PAE had lower mean (SD) FA in white matter of the left postcentral (0.35 [0.05] vs 0.36 [0.04]; mean difference, -0.02 [95% CI, -0.03 to -0.01]), left inferior parietal (0.31 [0.07] vs 0.33 [0.06]; mean difference, -0.03 [95% CI, -0.04 to -0.01]), left planum temporale (0.26 [0.04] vs 0.28 [0.03]; mean difference, -0.02 [95% CI, -0.03 to -0.01]), left inferior occipital (0.30 [0.07] vs 0.32 [0.05]; mean difference, -0.03 [95% CI, -0.04 to -0.01]), and right middle occipital (0.30 [0.04] vs 0.31 [0.04]; mean difference, -0.01 [95% CI, -0.02 to -0.01]) areas compared with controls, and higher FA in the gray matter of the putamen (0.22 [0.03] vs 0.21 [0.02]; mean difference, 0.01 [95% CI, 0.005-0.02]). Externalizing behavior scores were higher (worse) in children with PAE than in controls (mean [SD], 45.2 [9.0] vs 42.8 [9.0]; mean difference, 2.39 [95% CI, 0.30-4.47]). Several of these regions had significant group-behavior interactions, such that the higher FA was associated with less problematic behaviors in controls (ρ range, -0.24 to -0.08) but no associations were present in the PAE group (ρ range, 0.02-0.16).

CONCLUSIONS AND RELEVANCE

In this cross-sectional study, children with low levels of PAE had lower FA and more behavioral problems compared with a well-matched control group. These results suggest that PAE, even in small amounts, has a measurable effect on brain structure in children.

Increased functional interaction within frontoparietal network during working memory task in major depressive disorder

Abnormal fronto-parietal activation has been suggested as a neural underpinning of the working memory (WM) deficits in major depressive disorder (MDD). However, the potential interaction within the frontoparietal network during WM processing in MDD remains unclear. This study aimed to examine the role of abnormal functional interactions within frontoparietal network in the neuropathological mechanisms of WM deficits in MDD. A total of 40 MDD patients and 47 demographic matched healthy controls (HCs) were included. Functional magnetic resonance imaging and behavioral data were collected during numeric n-back tasks. The psychophysiological interaction and dynamic causal modelling methods were applied to investigate the connectivity within the frontoparietal network in MDD during n-back tasks. The psychophysiological interaction analysis revealed that MDD patients showed increased functional connectivity between the right inferior parietal lobule (IPL) and the right dorsolateral prefrontal cortex (dlPFC) compared with HCs during the 2-back task. The dynamic causal modelling analysis revealed that MDD patients had significantly increased forward modulation connectivity from the right IPL to the right dlPFC than HCs during the 2-back task. Partial correlation was used to calculate the relationship between connective parameters and psychological variables in the MDD group, which showed that the effective connectivity from right IPL to right dlPFC was correlated negatively with the sensitivity index d' of WM performances and positively with the depressive severity in MDD group. In conclusion, the abnormal functional and effective connectivity between frontal and parietal regions might contribute to explain the neuropathological mechanism of working memory deficits in major depressive disorder.

Chronic alcohol exposure during critical developmental periods differentially impacts persistence of deficits in cognitive flexibility and related circuitry

Cognitive flexibility in decision making depends on prefrontal cortical function and is used by individuals to adapt to environmental changes in circumstances. Cognitive flexibility can be measured in the laboratory using a variety of discrete, translational tasks, including those that involve reversal learning and/or set-shifting ability. Distinct components of flexible behavior rely upon overlapping brain circuits, including different prefrontal substructures that have separable impacts on decision making. Cognitive flexibility is impaired after chronic alcohol exposure, particularly during development when the brain undergoes rapid maturation. This review examines how cognitive flexibility, as indexed by reversal and set-shifting tasks, is impacted by chronic alcohol exposure in adulthood, adolescent, and prenatal periods in humans and animal models. We also discuss areas for future study, including mechanisms that may contribute to the persistence of cognitive deficits after developmental alcohol exposure and the compacting consequences from exposure across multiple critical periods.

Effects of Prenatal Alcohol Exposure on the Volumes of the Lateral and Medial Walls of the Intraparietal Sulcus

Fetal alcohol spectrum disorders (FASD) continue to be the leading preventable cause of intellectual disability in the U.S., Europe, and in endemic areas, such as the Western Cape region of South Africa. Arithmetic is highly sensitive to prenatal alcohol exposure (PAE). The intraparietal sulcus (IPS) is known to play a critical role in number processing. In this study, we investigate whether smaller IPS volumes play a role in the number-processing deficits observed in children with PAE. Participants were 52 9- to 14-year-old children from a historically disadvantaged community in Cape Town, who are participating in our ongoing studies on the effects of PAE on the brain. The IPS was manually parcellated into its medial (MIPS) and lateral (LIPS) walls on magnetic resonance images. The study aimed to examine: (1) the effects of PAE on IPS regional volumes and asymmetry, (2) whether IPS regional volumes are related to number processing performance and, if so, whether these relations are moderated by PAE and (3) potential mediation by regional IPS volumes of the relation between PAE and number processing performance. Total intracranial volume (TIV) was associated with volumes in all regions except the right LIPS. Both left MIPS and left LIPS volumes were significantly smaller in children in the fetal alcohol syndrome (FAS)/partial FAS (PFAS) group compared to controls. The finding in the left LIPS remained significant after controlling for potential confounders and after adjustment for the smaller overall brain size of the children in the FAS/PFAS group. Smaller left LIPS volumes in the FAS/PFAS group may account for the absence of left-right asymmetry in the LIPS in children with FAS/PFAS compared to controls and nonsyndromal heavily exposed (HE) children. Bilaterally, larger MIPS volumes were associated with better WISC IQ Arithmetic scores. These effects, however, were not moderated by the degree of PAE, and regional IPS volumes did not mediate the effect of PAE on WISC Arithmetic scores. Although we found that certain regions of the IPS were smaller in children with FAS and PFAS, these PAE-induced changes in IPS volume did not mediate the alcohol-related deficits in arithmetic.

Mechanisms of context conditioning in the developing rat

The article reviews our studies of contextual fear conditioning (CFC) in rats during a period of development---Postnatal Day (PND) 17-33---that represents the late-infant, juvenile, and early-adolescent stages. These studies seek to acquire 'systems level' knowledge of brain and memory development and apply it to a rodent model of Fetal Alcohol Spectrum Disorder (FASD). This rodent model focuses on alcohol exposure from PND4-9, a period of brain development equivalent to the human third trimester, when neocortex, hippocampus, and cerebellum are especially vulnerable to adverse effects of alcohol. Our research emphasizes a variant of CFC, termed the Context Preexposure Facilitation Effect (CPFE, Fanselow, 1990), in which context representations incidentally learned on one occasion are retrieved and associated with immediate shock on a subsequent occasion. These representations can be encoded at the earliest developmental stage but seem not to be retained or retrieved until the juvenile period. This is associated with developmental differences in context-elicited expression, in prefrontal cortex, hippocampus, and amygdala, of immediate early genes (IEGs) that are implicated in long-term memory. Loss-of-function studies establish a functional role for these regions as soon as the CPFE emerges during ontogeny. In our rodent model of FASD, the CPFE is much more sensitive to alcohol dose than other commonly used cognitive tasks. This impairment can be reversed by acute administration during behavioral testing of drugs that enhance cholinergic function. This effect is associated with normalized IEG expression in prefrontal cortex during incidental context learning. In summary, our findings suggest that long-term memory of incidentally-learned context representations depends on prefrontal-hippocampal circuitry that is important both for the normative development of context conditioning and for its disruption by developmental alcohol exposure.

Altered Resting-State Neural Oscillations and Spectral Power in Children with Fetal Alcohol Spectrum Disorder

BACKGROUND

Consumption of alcohol during pregnancy impacts fetal development and may lead to a variety of physical, cognitive, and behavioral abnormalities in childhood collectively known as fetal alcohol spectrum disorder (FASD). The FASD spectrum includes children with fetal alcohol syndrome (FAS), partial fetal alcohol syndrome (pFAS), and alcohol-related neurodevelopmental disorder (ARND). Children with a FASD or prenatal alcohol exposure (PAE) have impaired white matter, reduced structural volumes, impaired resting-state functional connectivity when measured with fMRI, and spectral hypersynchrony as infants. Magnetoencephalography (MEG) provides high temporal resolution and good spatial precision for examining spectral power and connectivity patterns unique from fMRI. The impact of PAE on MEG resting-state spectral power in children remains unknown.

METHODS

We collected 2 minutes of eyes-open and eyes-closed resting-state data in 51 children (8 to 12 years of age) with 3 subgroups included: 10 ARND/PAE, 15 FAS/pFAS, and 26 controls (TDC). MEG data were collected on the Elekta Neuromag system. The following spectral metrics were compared between subgroups: power, normalized power, half power, 95% power, and Shannon spectral entropy (SSE). MEG spectral data were correlated with behavioral measures.

RESULTS

Our results indicate children with FAS/pFAS had reduced spectral power and normalized power, particularly within the alpha frequency band in sensor parietal and source superior parietal and lateral occipital regions, along with elevated half power, 95% power, and SSE. We also found select hemisphere specific effects further indicating reduced corpus callosum connectivity in children with a FASD. Interestingly, while the ARND/PAE subgroup had significant differences from the FAS/pFAS subgroup, in many cases spectral data were not significantly different from TDC.

CONCLUSIONS

Our results were consistent with previous studies and provide new insight into resting-state oscillatory differences both between children with FAS and TDC, and within FASD subgroups. Further understanding of these resting-state variations and their impact on cognitive function may help provide early targets for intervention and enhance outcomes for individuals with a FASD.

Alcohol use in pregnancy and its impact on the mother and child

AIMS

To review the impact of prenatal alcohol exposure on the outcomes of the mother and child.

DESIGN

Narrative review.

SETTING

Review of literature.

PARTICIPANTS

Mothers and infants affected by prenatal alcohol use.

MEASUREMENTS

Outcomes of mothers and children.

FINDINGS

Prenatal alcohol exposure is one of the most important causes of preventable cognitive impairment in the world. The developing neurological system is exquisitely sensitive to harm from alcohol and there is now also substantial evidence that alcohol-related harm can extend beyond the individual person, leading to epigenetic changes and intergenerational vulnerability and disadvantage. There is no known safe level or timing of drinking for pregnant or lactating women and binge drinking (> four drinks within 2 hours for women) is the most harmful. Alcohol-exposure increases the risk of congenital problems, including Fetal Alcohol Spectrum Disorder (FASD) and its most severe form, Fetal Alcohol Syndrome (FAS).

CONCLUSION

The impact of FASD and FAS is enduring and life-long with no current treatment or cure. Emerging therapeutic options may mitigate the worst impact of alcohol exposure but significant knowledge gaps remain. This review discusses the history, epidemiology and clinical presentations of prenatal alcohol exposure, focusing on FASD and FAS, and the impact of evidence on future research, practice and policy directions.

A randomized controlled trial of transcranial direct-current stimulation and cognitive training in children with fetal alcohol spectrum disorder

BACKGROUND

This study was a randomized double-blind sham-controlled trial examining the effects of transcranial direct current stimulation (tDCS) augmented cognitive training (CT) in children with Fetal Alcohol Spectrum Disorders (FASD). Prenatal alcohol exposure has profound detrimental effects on brain development and individuals with FASD commonly present with deficits in executive functions including attention and working memory. The most commonly studied treatment for executive deficits is CT, which involves repeated drilling of exercises targeting the impaired functions. As currently implemented, CT requires many hours and the observed effect sizes are moderate. Neuromodulation via tDCS can enhance brain plasticity and prior studies demonstrate that combining tDCS with CT improves efficacy and functional outcomes. TDCS-augmented CT has not yet been tested in FASD, a condition in which there are known abnormalities in neuroplasticity and few interventions.

METHODS

This study examined the feasibility and efficacy of this approach in 44 children with FASD. Participants were randomized to receive five sessions of CT with either active or sham tDCS targeting the dorsolateral prefrontal cortex, a region of the brain that is heavily involved in executive functioning.

RESULTS

The intervention was feasible and well-tolerated in children with FASD. The tDCS group showed nominally significant improvement in attention on a continuous performance test compared to sham (p = .043). Group differences were observed at the third, fourth and fifth treatment sessions. There was no effect of tDCS on working memory (p = .911). Further, we found no group differences on a trail making task (p = .659) or on the verbal fluency test (p = .826). In the active tDCS group, a significant correlation was observed between improvement in attention scores and decrease in parent-reported attention deficits (p = .010).

CONCLUSIONS

These results demonstrate that tDCS-augmented CT is well tolerated in children with FASD and potentially offers benefits over and above CT alone.

Functional Connectome of the Fetal Brain

Large-scale functional connectome formation and reorganization is apparent in the second trimester of pregnancy, making it a crucial and vulnerable time window in connectome development. Here we identified which architectural principles of functional connectome organization are initiated before birth, and contrast those with topological characteristics observed in the mature adult brain. A sample of 105 pregnant women participated in human fetal resting-state fMRI studies (fetal gestational age between 20 and 40 weeks). Connectome analysis was used to analyze weighted network characteristics of fetal macroscale brain wiring. We identified efficient network attributes, common functional modules, and high overlap between the fetal and adult brain network. Our results indicate that key features of the functional connectome are present in the second and third trimesters of pregnancy. Understanding the organizational principles of fetal connectome organization may bring opportunities to develop markers for early detection of alterations of brain function.SIGNIFICANCE STATEMENT The fetal to neonatal period is well known as a critical stage in brain development. Rapid neurodevelopmental processes establish key functional neural circuits of the human brain. Prenatal risk factors may interfere with early trajectories of connectome formation and thereby shape future health outcomes. Recent advances in MRI have made it possible to examine fetal brain functional connectivity. In this study, we evaluate the network topography of normative functional network development during connectome genesis in utero Understanding the developmental trajectory of brain connectivity provides a basis for understanding how the prenatal period shapes future brain function and disease dysfunction.

The brain's functional connectome in young children with prenatal alcohol exposure

Prenatal alcohol exposure (PAE) can lead to altered brain function and structure, as well as lifelong cognitive, behavioral, and mental health difficulties. Previous research has shown reduced brain network efficiency in older children and adolescents with PAE, but no imaging studies have examined brain differences in young children with PAE, at an age when cognitive and behavioral problems often first become apparent. The present study aimed to investigate the brain's functional connectome in young children with PAE using passive viewing fMRI. We analyzed 34 datasets from 26 children with PAE aged 2-7 years and 215 datasets from 87 unexposed typically-developing children in the same age range. The whole brain functional connectome was constructed using functional connectivity analysis across 90 regions for each dataset. We examined intra- and inter-participant stability of the functional connectome, graph theoretical measurements, and their correlations with age. Children with PAE had similar inter- and intra-participant stability to controls. However, children with PAE, but not controls, showed increasing intra-participant stability with age, suggesting a lack of variability of intrinsic brain activity over time. Inter-participant stability increased with age in controls but not in children with PAE, indicating more variability of brain function across the PAE population. Global graph metrics were similar between children with PAE and controls, in line with previous studies in older children. This study characterizes the functional connectome in young children with PAE for the first time, suggesting that the increased brain variability seen in older children develops early in childhood, when participants with PAE fail to show the expected age-related increases in inter-individual stability.

Cholinergic rescue of neurocognitive insult following third-trimester equivalent alcohol exposure in rats

Neonatal ethanol exposure during the third trimester equivalent of human pregnancy in the rat significantly impairs hippocampal and prefrontal neurobehavioral functioning. Postnatal day [PD] 4-9 ethanol exposure in rats disrupts long-term context memory formation, resulting in abolished post-shock and retention test freezing in a variant of contextual fear conditioning called the Context Preexposure Facilitation Effect (CPFE). This behavioral impairment is accompanied by disrupted medial prefrontal, but not dorsal hippocampal expression of the immediate early genes (IEGs) c-Fos, Arc, Egr-1, and Npas4 (Heroux, Robinson-Drummer, Kawan, Rosen, & Stanton, 2019). The current experiment examined if systemic administration of the acetylcholinesterase inhibitor physostigmine (PHY) prior to context learning would rescue prefrontal IEG expression and freezing in the CPFE. From PD4-9, Long-Evans rats received oral intubation of ethanol (EtOH; 5.25 g/kg/day) or sham-intubation (SI). Rats received a systemic injection of saline (SAL) or PHY (0.01 mg/kg) prior to all three phases (Experiment 1) or just context exposure (Experiment 2) in the CPFE from PD31-33. A subset of rats were sacrificed 30 min after context learning to assay changes in IEG expression in the medial prefrontal cortex (mPFC), dorsal hippocampus (dHPC), and ventral hippocampus (vHPC). Administration of PHY prior to all three phases or just context learning rescued both post-shock and retention test freezing in the CPFE in EtOH rats without altering performance in SI rats. EtOH-SAL rats had significantly reduced mPFC but not dHPC expression of c-Fos, Arc, Egr-1, and Npas4. EtOH-PHY treatment rescued mPFC expression of c-Fos in ethanol-exposed rats and increased Arc and Npas4 regardless of dosing condition. While there was no effect of PHY on dHPC or vHPC expression of Arc, Egr-1, or Npas4, this treatment significantly boosted hippocampal expression of c-Fos regardless of ethanol treatment. These findings implicate impaired cholinergic and prefrontal function in cognitive deficits arising from 3rd-trimester equivalent alcohol exposure.

Clinical presentation, diagnosis, and management of fetal alcohol spectrum disorder

Although prenatal alcohol exposure causes craniofacial anomalies, growth retardation, neurological abnormalities, cognitive impairment, and birth defects, fetal alcohol spectrum disorder is underdiagnosed. Global prevalence of fetal alcohol spectrum disorder is 0·77%, with a higher prevalence of 2-5% in Europe and North America, highlighting the need for increased diagnosis and treatment. However, diagnosis remains challenging because of the poor reliability of self-reported maternal drinking histories, an absence of sensitive biomarkers, and the infrequency of diagnostic dysmorphic facial features among individuals with fetal alcohol spectrum disorder. Different diagnostic systems and disagreements over criteria have slowed progress in the diagnosis and management of the disorder. Neuroimaging shows abnormalities in brain structure, cortical development, white matter microstructure, and functional connectivity in individuals with fetal alcohol spectrum disorder. These abnormalities modify developmental trajectories and are associated with deficits in cognition, executive function, memory, vision, hearing, motor skills, behaviour, and social adaptation. Promising trials of nutritional interventions and cognitive rehabilitation therapies are underway, with the aim of treating cognitive deficits in fetal alcohol spectrum disorders.

Fetal Alcohol Spectrum Disorders: A Review of the Neurobehavioral Deficits Associated With Prenatal Alcohol Exposure

In utero alcohol exposure can disrupt the development of the fetal brain and result in a wide range of neurobehavioral outcomes collectively known as fetal alcohol spectrum disorders (FASD). This paper provides a comprehensive review of the cognitive and behavioral outcomes of prenatal alcohol exposure, including domains of general intelligence, executive functioning, language development, learning and memory, adaptive functioning, academic performance, and concurrent psychopathology. In addition, the current status of the neurobehavioral profile of FASD and its potential as a diagnostic tool will be discussed.

Neonatal ethanol exposure impairs long-term context memory formation and prefrontal immediate early gene expression in adolescent rats

Fetal alcohol exposure leads to severe disruptions in learning and memory involving the hippocampus and prefrontal cortex in humans. Animal model research on FASD has documented impairment of hippocampal neuroanatomy and function but animal studies of cognition involving the prefrontal cortex are sparse. We have found that a variant of contextual fear conditioning in which both the hippocampus and prefrontal cortex is required, the Context Preexposure Facilitation Effect (CPFE), is particularly sensitive to neurobehavioral disruption caused by neonatal ethanol exposure during the third trimester equivalent of human pregnancy in the rat (i.e., PD4-9). In the CPFE, learning about the context, acquiring a context-shock association, and retrieving contextual fear are temporally separated across three days. The current study asked whether neonatal alcohol exposure impairs context learning, consolidation, or retrieval and examined prefrontal and hippocampal molecular signaling as correlates of this impairment. Long-Evans rats that received oral intubation of ethanol (AE; 5.25 g/kg/day, split into two doses) or underwent sham-intubation (SI) from PND4-9 were tested on the CPFE on PD31-33. Extending our previous reports, ethanol abolished both post-shock and retention test freezing in the CPFE. Assays (qPCR) of immediate early gene expression revealed that ethanol disrupted prefrontal but not hippocampal expression of c-Fos, Arc, Egr-1, and Npas4 during context learning. Finally, ethanol-exposed animals were unimpaired in a standard contextual fear conditioning procedure in which learning about the context and acquiring a context-shock association occurs concurrently. These findings implicate impaired prefrontal function in cognitive deficits arising from 3rd-trimester equivalent alcohol exposure in the rat.