Children with heavy prenatal alcohol exposure have different frequency domain signal characteristics when producing isometric force

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.

Moderate Maternal Alcohol Exposure on Gestational Day 12 Impacts Anxiety-Like Behavior in Offspring

Among the numerous consequences of prenatal alcohol exposure (PAE) is an increase in anxiety-like behavior that can prove debilitating to daily functioning. A significant body of literature has linked gestational day 12 (G12) heavy ethanol exposure with social anxiety, evident in adolescent males and females. However, the association between non-social anxiety-like behavior and moderate alcohol exposure, a more common pattern of drinking in pregnant women, is yet unidentified. To model moderate PAE (mPAE), we exposed pregnant Sprague-Dawley rats to either room air or vaporized ethanol for 6 h on G12. Adolescent offspring were then tested on postnatal days (P) 41-47 in one of the following four anxiety assays: novelty-induced hypophagia (NIH), elevated plus maze (EPM), light-dark box (LDB) and open-field (OF). Our findings revealed significant increases in measures of anxiety-like behavior in male PAE offspring in the NIH, LDB and OF, with no differences observed in females on any test. Additionally, male offspring who demonstrated heightened anxiety-like behavior as adolescents demonstrated decreased anxiety-like behavior in adulthood, as measured by a marble-burying test (MBT), while females continued to be unaffected in adulthood. These results suggest that mPAE leads to dynamic changes in anxiety-like behavior exclusively in male offspring.

Children with Heavy Prenatal Alcohol Exposure Exhibit Atypical Gait Characteristics

BACKGROUND

Impaired motor function in children with histories of prenatal exposure to alcohol has been previously reported but, to date, no studies using quantitatively based analyses have been performed to assess gait in these children.

METHODS

Gait of children with (n = 18) or without (n = 26) prenatal alcohol exposure was assessed using an electronically instrumented walkway. Children completed blocks of trials traversing the walkway with different combinations of walking condition (increased, self-paced, and decreased cadence) and direction (forward and backward). Gait velocity, cadence, stride length, step width, foot angle, and double support time, as well as the variability of these temporal-spatial markers, were used to assess gait.

RESULTS

Results indicated that, in comparison with typically developing children, alcohol-exposed children produced exaggerated foot angle and increased step width. Additionally, alcohol-exposed children produced greater intrasubject variability of gait velocity and walking cadence while walking forward and backward, and greater variability in step width when walking backward and for all 3 walking conditions.

CONCLUSIONS

The results indicate that selected gait markers are adversely affected by prenatal exposure to alcohol. Clinicians and front-line personnel (e.g., teachers) should provide movement enriched experiences to help ameliorate these alcohol-related deficits.

Ifenprodil infusion in agranular insular cortex alters social behavior and vocalizations in rats exposed to moderate levels of ethanol during prenatal development

Moderate exposure to alcohol during development leads to subtle neurobiological and behavioral effects classified under the umbrella term fetal alcohol spectrum disorders (FASDs). Alterations in social behaviors are a frequently observed consequence of maternal drinking, as children with FASDs display inappropriate aggressive behaviors and altered responses to social cues. Rodent models of FASDs mimic the behavioral alterations seen in humans, with rats exposed to ethanol during development displaying increased aggressive behaviors, decreased social investigation, and altered play behavior. Work from our laboratory has observed increased wrestling behavior in adult male rats following prenatal alcohol exposure (PAE), and increased expression of GluN2B-containing NMDA receptors in the agranular insular cortex (AIC). This study was undertaken to determine if ifenprodil, a GluN2B preferring negative allosteric modulator, has a significant effect on social behaviors in PAE rats. Using a voluntary ethanol exposure paradigm, rat dams were allowed to drink a saccharin-sweetened solution of either 0% or 5% ethanol throughout gestation. Offspring at 6-8 months of age were implanted with cannulae into AIC. Animals were isolated for 24h before ifenprodil or vehicle was infused into AIC, and after 15min they were recorded in a social interaction chamber. Ifenprodil treatment altered aspects of wrestling, social investigatory behaviors, and ultrasonic vocalizations in rats exposed to ethanol during development that were not observed in control animals. These data indicate that GluN2B-containing NMDA receptors in AIC play a role in social behaviors and may underlie alterations in behavior and vocalizations observed in PAE animals.

Effects of sex and housing on social, spatial, and motor behavior in adult rats exposed to moderate levels of alcohol during prenatal development

Persistent deficits in social behavior, motor behavior, and behavioral flexibility are among the major negative consequences associated with exposure to ethanol during prenatal development. Prior work from our laboratory has linked moderate prenatal alcohol exposure (PAE) in the rat to deficits in these behavioral domains, which depend upon the ventrolateral frontal cortex (Hamilton et al., 2014) [20]. Manipulations of the social environment cause modifications of dendritic morphology and experience-dependent immediate early gene expression in ventrolateral frontal cortex (Hamilton et al., 2010) [19], and may yield positive behavioral outcomes following PAE. In the present study we evaluated the effects of housing PAE rats with non-exposed control rats on adult behavior. Rats of both sexes were either paired with a partner from the same prenatal treatment condition (ethanol or saccharin) or from the opposite condition (mixed housing condition). At four months of age (∼3 months after the housing manipulation commenced), social behavior, tongue protrusion, and behavioral flexibility in the Morris water task were measured as in (Hamilton et al., 2014) [20]. The behavioral effects of moderate PAE were primarily limited to males and were not ameliorated by housing with a non-ethanol exposed partner. Unexpectedly, social behavior, motor behavior, and spatial flexibility were adversely affected in control rats housed with a PAE rat (i.e., in mixed housing), indicating that housing with a PAE rat has broad behavioral consequences beyond the social domain. These observations provide further evidence that moderate PAE negatively affects social behavior, and underscore the importance of considering potential negative effects of housing with PAE animals on the behavior of critical comparison groups.

Moderate prenatal alcohol exposure enhances GluN2B containing NMDA receptor binding and ifenprodil sensitivity in rat agranular insular cortex

Prenatal exposure to alcohol affects the expression and function of glutamatergic neurotransmitter receptors in diverse brain regions. The present study was undertaken to fill a current gap in knowledge regarding the regional specificity of ethanol-related alterations in glutamatergic receptors in the frontal cortex. We quantified subregional expression and function of glutamatergic neurotransmitter receptors (AMPARs, NMDARs, GluN2B-containing NMDARs, mGluR1s, and mGluR5s) by radioligand binding in the agranular insular cortex (AID), lateral orbital area (LO), prelimbic cortex (PrL) and primary motor cortex (M1) of adult rats exposed to moderate levels of ethanol during prenatal development. Increased expression of GluN2B-containing NMDARs was observed in AID of ethanol-exposed rats compared to modest reductions in other regions. We subsequently performed slice electrophysiology measurements in a whole-cell patch-clamp preparation to quantify the sensitivity of evoked NMDAR-mediated excitatory postsynaptic currents (EPSCs) in layer II/III pyramidal neurons of AID to the GluN2B negative allosteric modulator ifenprodil. Consistent with increased GluN2B expression, ifenprodil caused a greater reduction in NMDAR-mediated EPSCs from prenatal alcohol-exposed rats than saccharin-exposed control animals. No alterations in AMPAR-mediated EPSCs or the ratio of AMPARs/NMDARs were observed. Together, these data indicate that moderate prenatal alcohol exposure has a significant and lasting impact on GluN2B-containing receptors in AID, which could help to explain ethanol-related alterations in learning and behaviors that depend on this region.

Importance of genetics in fetal alcohol effects: null mutation of the nNOS gene worsens alcohol-induced cerebellar neuronal losses and behavioral deficits

The cerebellum is a major target of alcohol-induced damage in the developing brain. However, the cerebella of some children are much more seriously affected than others by prenatal alcohol exposure. As a consequence of in utero alcohol exposure, some children have substantial reductions in cerebellar volume and corresponding neurodevelopmental problems, including microencephaly, ataxia, and balance deficits, while other children who were exposed to similar alcohol quantities are spared. One factor that likely plays a key role in determining the impact of alcohol on the fetal cerebellum is genetics. However, no specific gene variant has yet been identified that worsens cerebellar function as a consequence of developmental alcohol exposure. Previous studies have revealed that mice carrying a homozygous mutation of the gene for neuronal nitric oxide synthase (nNOS-/- mice) have more severe acute alcohol-induced neuronal losses from the cerebellum than wild type mice. Therefore, the goals of this study were to determine whether alcohol induces more severe cerebellum-based behavioral deficits in nNOS-/- mice than in wild type mice and to determine whether these worsened behavior deficits are associated with worsened cerebellar neuronal losses. nNOS-/- mice and their wild type controls received alcohol (0.0, 2.2, or 4.4mg/g) daily over postnatal days 4-9. In adulthood, the mice underwent behavioral testing, followed by neuronal quantification. Alcohol caused dose-related deficits in rotarod and balance beam performance in both nNOS-/- and wild type mice. However, the alcohol-induced behavioral deficits were substantially worse in the nNOS-/- mice than in wild type. Likewise, alcohol exposure led to losses of Purkinje cells and cerebellar granule cells in mice of both genotypes, but the cell losses were more severe in the nNOS-/- mice than in wild type. Behavioral performances were correlated with neuronal number in the nNOS-/- mice, but not in wild type. Thus, homozygous mutation of the nNOS gene increases vulnerability to alcohol-induced cerebellar dysfunction and neuronal loss. nNOS is the first gene identified whose mutation worsens alcohol-induced cerebellar behavioral deficits.

Effects of moderate prenatal ethanol exposure and age on social behavior, spatial response perseveration errors and motor behavior

Persistent deficits in social behavior are among the major negative consequences associated with exposure to ethanol during prenatal development. Prior work from our laboratory has linked deficits in social behavior following moderate prenatal alcohol exposure (PAE) in the rat to functional alterations in the ventrolateral frontal cortex [21]. In addition to social behaviors, the regions comprising the ventrolateral frontal cortex are critical for diverse processes ranging from orofacial motor movements to flexible alteration of behavior in the face of changing consequences. The broader behavioral implications of altered ventrolateral frontal cortex function following moderate PAE have, however, not been examined. In the present study we evaluated the consequences of moderate PAE on social behavior, tongue protrusion, and flexibility in a variant of the Morris water task that required modification of a well-established spatial response. PAE rats displayed deficits in tongue protrusion, reduced flexibility in the spatial domain, increased wrestling, and decreased investigation, indicating that several behaviors associated with ventrolateral frontal cortex function are impaired following moderate PAE. A linear discriminant analysis revealed that measures of wrestling and tongue protrusion provided the best discrimination of PAE rats from saccharin-exposed control rats. We also evaluated all behaviors in young adult (4-5 months) or older (10-11 months) rats to address the persistence of behavioral deficits in adulthood and possible interactions between early ethanol exposure and advancing age. Behavioral deficits in each domain persisted well into adulthood (10-11 months), however, there was no evidence that aging enhances the effects of moderate PAE within the age ranges that were studied.

Automated cerebellar segmentation: Validation and application to detect smaller volumes in children prenatally exposed to alcohol

OBJECTIVE

To validate an automated cerebellar segmentation method based on active shape and appearance modeling and then segment the cerebellum on images acquired from adolescents with histories of prenatal alcohol exposure (PAE) and non-exposed controls (NC).

METHODS

Automated segmentations of the total cerebellum, right and left cerebellar hemispheres, and three vermal lobes (anterior, lobules I-V; superior posterior, lobules VI-VII; inferior posterior, lobules VIII-X) were compared to expert manual labelings on 20 subjects, studied twice, that were not used for model training. The method was also used to segment the cerebellum on 11 PAE and 9 NC adolescents.

RESULTS

The test-retest intraclass correlation coefficients (ICCs) of the automated method were greater than 0.94 for all cerebellar volume and mid-sagittal vermal area measures, comparable or better than the test-retest ICCs for manual measurement (all ICCs > 0.92). The ICCs computed on all four cerebellar measurements (manual and automated measures on the repeat scans) to compare comparability were above 0.97 for non-vermis parcels, and above 0.89 for vermis parcels. When applied to patients, the automated method detected smaller cerebellar volumes and mid-sagittal areas in the PAE group compared to controls (p < 0.05 for all regions except the superior posterior lobe, consistent with prior studies).

DISCUSSION

These results demonstrate excellent reliability and validity of automated cerebellar volume and mid-sagittal area measurements, compared to manual measurements. These data also illustrate that this new technology for automatically delineating the cerebellum leads to conclusions regarding the effects of prenatal alcohol exposure on the cerebellum consistent with prior studies that used labor intensive manual delineation, even with a very small sample.

The importance of measurement precision and behavioral homologies in evaluating the behavioral consequences of fetal-ethanol exposure: commentary on Williams and colleagues ("Sensory-motor deficits in children with fetal alcohol spectrum disorder assessed using a robotic virtual reality platform")

The recent study by Willams and colleagues utilized a novel robotic virtual reality measurement system to measure sensory-motor processing deficits in children with fetal alcohol spectrum disorders (FASDs). This system and the precise quantitation of distinct constituent behavioral processes may hold considerable utility and importance for the study of FASD-related motor deficits, their neural bases, and translational research efforts using homologous behavioral approaches in animal and human studies..