Corpus callosum shape and neuropsychological deficits in adult males with heavy fetal alcohol exposure

Regional shape change in adult facial bone curvature with age

Life expectancies have increased dramatically over the last 100 years, affording greater opportunities to study the impact of age on adult craniofacial morphology. This article employs a novel application of established geometric morphometric methods to examine shape differences in adult regional facial bone curvature with age. Three-dimensional semilandmarks representing the curvature of the orbits, zygomatic arches, nasal aperture, and maxillary alveolar process were collected from a cross-sectional cranial sample of mixed sex and ancestry (male and female; African- and European-American), partitioned into three age groups (young adult = 18-39; middle-aged = 40-59 years; and elderly = 60+ years). Each facial region's semilandmarks were aligned into a common coordinate system via generalized Procrustes superimposition. Regional variation in shape was then explored via a battery of multivariate statistical techniques. Age-related shape differences were detected in the orbits, zygomatic arches, and maxillary alveolar process. Interactions between age, sex, and ancestry were also identified. Vector plots revealed patterns of superoinferior compression, lateral expansion, and posterior recession depending on the population/subpopulation, location, and age groups examined. These findings indicate that adult craniofacial curvature shape is not static throughout human life. Instead, age-related spatial modifications occur in various regions of the craniofacial skeleton. Moreover, these regional alterations vary not only through time, but across human populations and the sexes.

Structural, metabolic, and functional brain abnormalities as a result of prenatal exposure to drugs of abuse: evidence from neuroimaging

Prenatal exposure to alcohol and stimulants negatively affects the developing trajectory of the central nervous system in many ways. Recent advances in neuroimaging methods have allowed researchers to study the structural, metabolic, and functional abnormalities resulting from prenatal exposure to drugs of abuse in living human subjects. Here we review the neuroimaging literature of prenatal exposure to alcohol, cocaine, and methamphetamine. Neuroimaging studies of prenatal alcohol exposure have reported differences in the structure and metabolism of many brain systems, including in frontal, parietal, and temporal regions, in the cerebellum and basal ganglia, as well as in the white matter tracts that connect these brain regions. Functional imaging studies have identified significant differences in brain activation related to various cognitive domains as a result of prenatal alcohol exposure. The published literature of prenatal exposure to cocaine and methamphetamine is much smaller, but evidence is beginning to emerge suggesting that exposure to stimulant drugs in utero may be particularly toxic to dopamine-rich basal ganglia regions. Although the interpretation of such findings is somewhat limited by the problem of polysubstance abuse and by the difficulty of obtaining precise exposure histories in retrospective studies, such investigations provide important insights into the effects of drugs of abuse on the structure, function, and metabolism of the developing human brain. These insights may ultimately help clinicians develop better diagnostic tools and devise appropriate therapeutic interventions to improve the condition of children with prenatal exposure to drugs of abuse.

Ventromedian forebrain dysgenesis follows early prenatal ethanol exposure in mice

Ethanol exposure on gestational day (GD) 7 in the mouse has previously been shown to result in ventromedian forebrain deficits along with facial anomalies characteristic of fetal alcohol syndrome (FAS). To further explore ethanol's teratogenic effect on the ventromedian forebrain in this mouse model, scanning electron microscopic and histological analyses were conducted. For this, time mated C57Bl/6J mice were injected with 2.9g/kg ethanol or saline twice, at a 4h interval, on their 7th day of pregnancy. On GD 12.5, 13 and 17, control and ethanol-exposed specimens were collected and processed for light and scanning electron microscopic analyses. Gross morphological changes present in the forebrains of ethanol-exposed embryos included cerebral hemispheres that were too close in proximity or rostrally united, enlarged foramina of Monro, enlarged or united lateral ventricles, and varying degrees of hippocampal and ventromedian forebrain deficiency. In GD 12.5 control and ethanol-exposed embryos, in situ hybridization employing probes for Nkx2.1 or Fzd8 to distinguish the preoptic area and medial ganglionic eminences (MGEs) from the lateral ganglionic eminences, respectively, confirmed the selective loss of ventromedian tissues. Immunohistochemical labeling of oligodendrocyte progenitors with Olig2, a transcription factor necessary for their specification, and of GABA, an inhibitory neurotransmitter, showed ethanol-induced reductions in both. To investigate later consequences of ventromedian forebrain loss, MGE-derived somatostatin-expressing interneurons in the subpallial region of GD 17 fetal mice were examined, with results showing that the somatostatin-expressing interneurons that were present were dysmorphic in the ethanol-exposed fetuses. The potential functional consequences of this insult are discussed.

Ontogeny of robusticity of craniofacial traits in modern humans: a study of South American populations

To date, differences in craniofacial robusticity among modern and fossil humans have been primarily addressed by analyzing adult individuals; thus, the developmental basis of such differentiation remains poorly understood. This article aims to analyze the ontogenetic development of craniofacial robusticity in human populations from South America. Geometric morphometric methods were used to describe cranial traits in lateral view by using landmarks and semilandmarks. We compare the patterns of variation among populations obtained with subadults and adults to determine whether population-specific differences are evident at early postnatal ontogeny, compare ontogenetic allometric trajectories to ascertain whether changes in the ontogeny of shape contribute to the differentiation of adult morphologies, and estimate the amount of size change that occurs during growth along each population-specific trajectory. The results obtained indicate that the pattern of interpopulation variation in shape and size is already established at the age of 5 years, meaning that processes acting early during ontogeny contribute to the adult variation. The ontogenetic allometric trajectories are not parallel among all samples, suggesting the divergence in the size-related shape changes. Finally, the extension of ontogenetic trajectories also seems to contribute to shape variation observed among adults.

Caudate asymmetry: a neurobiological marker of moderate prenatal alcohol exposure in young adults

This study identified structural changes in the caudate nucleus in offspring of mothers who drank moderate levels of alcohol during pregnancy. In addition, the effect of duration of alcohol use during pregnancy was assessed. Young adults were recruited from the Maternal Health Practices and Child Development Project. Three groups were evaluated: prenatal alcohol exposure (PAE) during all three trimesters (3T), PAE during the first trimester only (1T), and controls with no PAE (0T). Magnetic resonance images were processed using the automated labeling pathway technique. Volume was measured as the number (gray+white) and relative percentage (caudate count/whole brain count x 100) of voxels. Asymmetry was calculated by subtracting the caudate volume on the left from the right and dividing by the total (L-R/L+R). Data analyses controlled for gender, handedness, and prenatal tobacco and marijuana exposures. There were no significant differences between the groups for whole brain, left, or right volumes. There was a dose-response effect across the three exposure groups both in terms of magnitude and direction of asymmetry. In the 3T group, the left caudate was larger relative to the right caudate compared to the 0T group. The average magnitude of caudate asymmetry for the 1T group was intermediate between the 0T and 3T groups. Subtle anatomical changes in the caudate are detected at the moderate end of the spectrum of prenatal alcohol exposure.

Effects of prenatal tobacco, alcohol and marijuana exposure on processing speed, visual-motor coordination, and interhemispheric transfer

Deficits in motor control are often reported in children with prenatal alcohol exposure (PAE). Less is known about the effects of prenatal tobacco exposure (PTE) and prenatal marijuana exposure (PME) on motor coordination, and previous studies have not considered whether PTE, PAE, and PME interact to affect motor control. This study investigated the effects of PTE, PAE, and PME as well as current drug use on speed of processing, visual-motor coordination, and interhemispheric transfer in 16-year-old adolescents. Data were collected as part of the Maternal Health Practices and Child Development Project. Adolescents (age 16, n=320) participating in a longitudinal study of the effects of prenatal substance exposure on developmental outcomes were evaluated in this study. The computerized Bimanual Coordination Test (BCT) was used to assess each domain of function. Other important variables, such as demographics, home environment, and psychological characteristics of the mother and adolescent were also considered in the analyses. There were significant and independent effects of PTE, PAE, and PME on processing speed and interhemispheric transfer of information. PTE and PME were associated with deficits in visual-motor coordination. There were no interactions between PAE, PTE, and PME. Current tobacco use predicted deficits in speed of processing. Current alcohol and marijuana use by the offspring were not associated with any measures of performance on the BCT.

Ontogenetic change in skull morphology and mechanical advantage in the spotted hyena (Crocuta crocuta)

Weaning represents a challenging transition for young mammals, one particularly difficult for species coping with extreme conditions during feeding. Spotted hyenas (Crocuta crocuta) experience such extreme conditions imposed by intense feeding competition during which the ability to consume large quantities of food quickly is highly advantageous. As adult spotted hyenas have massive skulls specialized for durophagy and can feed very rapidly, young individuals are likely at a competitive disadvantage until that specialized morphology is completely developed. Here we document developmental changes in skull size, shape, and mechanical advantage of the jaws. Sampling an ontogenetic series of Crocuta skulls from individuals ranging in age from 2 months to 18 years, we use linear measurements and geometric morphometrics to test hypotheses suggesting that size, limited mechanical advantage of the jaws, and/or limited attachment sites for jaw muscles might constrain the feeding performance of juveniles. We also examine skull development in relation to key life history events, including weaning and reproductive maturity, to inquire whether ontogeny of the feeding apparatus is slower or more protracted in this species than in carnivores not specialized for durophagy. We find that, although mechanical advantage reaches maturity in hyenas at 22 months, adult skull size is not achieved until 29 months of age, and skull shape does not reach maturity until 35 months. The latter is nearly 2 years after mean weaning age, and more than 1 year after reproductive maturity. Thus, skull development in Crocuta is indeed protracted relative to that in most other carnivores. Based on the skull features that continue to change and to provide additional muscle attachment area, protracted development may be largely due to development of the massive musculature required by durophagy. These findings may ultimately shed light on the adaptive significance of the unusual "role-reversed" pattern of female dominance over males in this species.

Differentiating prenatal exposure to methamphetamine and alcohol versus alcohol and not methamphetamine using tensor-based brain morphometry and discriminant analysis

Here we investigate the effects of prenatal exposure to methamphetamine (MA) on local brain volume using magnetic resonance imaging. Because many who use MA during pregnancy also use alcohol, a known teratogen, we examined whether local brain volumes differed among 61 children (ages 5-15 years), 21 with prenatal MA exposure, 18 with concomitant prenatal alcohol exposure (the MAA group), 13 with heavy prenatal alcohol but not MA exposure (ALC group), and 27 unexposed controls. Volume reductions were observed in both exposure groups relative to controls in striatal and thalamic regions bilaterally and in right prefrontal and left occipitoparietal cortices. Striatal volume reductions were more severe in the MAA group than in the ALC group, and, within the MAA group, a negative correlation between full-scale intelligence quotient (FSIQ) scores and caudate volume was observed. Limbic structures, including the anterior and posterior cingulate, the inferior frontal gyrus (IFG), and ventral and lateral temporal lobes bilaterally, were increased in volume in both exposure groups. Furthermore, cingulate and right IFG volume increases were more pronounced in the MAA than ALC group. Discriminant function analyses using local volume measurements and FSIQ were used to predict group membership, yielding factor scores that correctly classified 72% of participants in jackknife analyses. These findings suggest that striatal and limbic structures, known to be sites of neurotoxicity in adult MA abusers, may be more vulnerable to prenatal MA exposure than alcohol exposure and that more severe striatal damage is associated with more severe cognitive deficit.

Prenatal alcohol exposure and childhood balance: a systematic review

Balance problems in childhood have known adverse psychosocial associations such as poorer quality of life and lower educational achievement. Previous longitudinal studies have documented an adverse effect of prenatal alcohol exposure on a variety of neurodevelopmental outcomes and so an effect on balance would seem plausible. This is supported by a previous laboratory study that found that rats exposed to ethanol in utero have dysfunctional balance and gait. The present study is a systematic review of the current evidence on the effects of maternal alcohol use during pregnancy on offspring balance in childhood. A search strategy was devised and applied in the CENTRAL database (Cochrane Collaboration). Prospective longitudinal studies were then sought using databases including Medline, EMBASE, PsychInfo, CINAHL and AMED. In addition, citations in relevant published papers and books were followed up and experts in the field were contacted. No relevant human experimental studies were found. Four longitudinal studies were found to have assessed balance in preschool children. Only one of these studies suggested strong or substantial effects of alcohol exposure on balance-related outcomes. However, this study appeared the most methodologically robust. In conclusion, at present, there is limited evidence on the possible effects of alcohol exposure on childhood balance.

Prenatal alcohol exposure reduces the size of the forelimb representation in motor cortex in rat: an intracortical microstimulation (ICMS) mapping study

Children with fetal alcohol spectrum disorder (FASD) often exhibit sensorimotor dysfunctions that include deficits in motor coordination and fine motor control. Although the underlying causes for these motor abnormalities are unknown, they likely involve interactions between sensory and motor systems. Rodent animal models have been used to study the effects of prenatal alcohol exposure (PAE) on skilled reaching and on the development and organization of somatosensory barrel field cortex. To this end, PAE delayed the development of somatosensory cortex, reduced the size of whisker and forelimb representations in somatosensory barrel field cortex, and delayed acquisition time to learn a skilled reaching task. However, whether PAE also affects the motor cortex (MI) remains to be determined. In the present study, we investigated the effect of PAE on the size of the forelimb representation in rat MI, thresholds for activation, and the overlap between motor and sensory cortical forelimb maps in sensorimotor cortex. Pregnant Sprague-Dawley rats were assigned to alcohol (Alc), pair-fed (PF), and chow-fed (CF) groups on gestation day 1 (GD1). Rats in the Alc group (n=4) were chronically intubated daily with binge doses of alcohol (6g/kg body weight) from GD1 to GD20 that resulted in averaged blood alcohol levels measured on GD10 (mean=191.5+/-41.9mg/dL) and on GD17 (mean=247.0+/-72.4mg/dL). PF (n=2) and CF (n=3) groups of pregnant rats served as controls. The effect of PAE on the various dependent measures was obtained from multiple male offspring from each dam within treatment groups, and litter means were compared between the groups from alcohol-treated and control (Ct: CF and PF) dams. At approximately 8 weeks of age, rats were anesthetized with ketamine/xylazine and the skull opened over sensorimotor cortex. A tungsten microelectrode was then inserted into the depths of layer V and intracortical microstimulation was used to deliver trains of pulses to evoke muscle contractions and/or movements; maximum stimulating < or =100microA. When a motor response was observed, the threshold for movement was measured and the motor receptive field projected to the cortical surface to serve as representative point for that location. A motor map for the forelimb representation was generated by systematically stimulating at adjacent sites until current thresholds reached the maximum and/or motor responses were no longer evoked. The major findings in this study were as follows: (1) PAE significantly reduced the area of the forelimb representation in the Alc offspring (6.01mm(2), standard error of the mean=+/-0.278) compared with the Ct offspring (8.03mm(2)+/-0.586), (2) PAE did not significantly reduce the averaged threshold for activation of movements between groups, (3) PAE significantly reduced the percent overlap (Alc=31.1%, Ct=55.4%) between the forelimb representation in sensory and motor cortices, and (4) no significant differences were observed in averaged body weight, hemisphere weight, or age of animal between treatment groups. These findings suggest that the effects of PAE are not restricted to somatosensory barrel field cortex but also involve the MI and may underlie deficits in motor control and sensorimotor integration observed among children with FASD.

Cingulate gyrus morphology in children and adolescents with fetal alcohol spectrum disorders

Alcohol consumption during pregnancy can lead to a variety of cognitive and other birth defects, collectively termed fetal alcohol spectrum disorders (FASD), and including the Fetal Alcohol Syndrome (FAS). This study examined the impact of gestational alcohol exposure on the morphology of the cingulate gyrus, given this region's role in cognitive control, attention, and emotional regulation, all of which are affected in children with FASD. Thirty-one youth (ages 8-16) with histories of heavy prenatal alcohol exposure (n=21) and demographically matched comparison subjects (n=10) underwent structural magnetic resonance imaging. The cingulate gyrus was manually delineated, and parcellated volumes of grey and white matter were compared across groups. Alcohol-exposed individuals had significantly smaller raw cingulate grey matter, white matter, and tissue volumes compared with controls. After adjustment for respective cranial tissue constituents, only white matter volumes remained significantly reduced, and this held regardless of whether or not the child qualified for a diagnosis of FAS. A correlation between posterior cingulate grey matter volume and the WISC-III Freedom from Distractibility Index was also observed in alcohol-exposed children. These data suggest that cingulate white matter is compromised beyond global white matter hypoplasia in alcohol-exposed individuals, regardless of FAS diagnosis. The observed volumetric reductions in the cingulate gyrus may contribute to the disruptive and emotionally dysregulated behavioral profile commonly observed in this population.

Magnetic resonance imaging outcomes from a comprehensive magnetic resonance study of children with fetal alcohol spectrum disorders

BACKGROUND

Magnetic resonance (MR) technology offers noninvasive methods for in vivo assessment of neuroabnormalities.

METHODS

A comprehensive neuropsychological/psychiatric battery, coupled with MR imaging, (MRI), MR spectroscopy (MRS), and functional MRI (fMRI) assessments, were administered to children with fetal alcohol spectrum disorders (FASD) to determine if global and/or focal abnormalities could be identified, and distinguish diagnostic subclassifications across the spectrum. The 4 study groups included: (i) fetal alcohol syndrome (FAS)/partial FAS (PFAS); (ii) static encephalopathy/alcohol exposed (SE/AE); (iii) neurobehavioral disorder/alcohol exposed (ND/AE) as diagnosed with the FASD 4-Digit Code; and (iv) healthy peers with no prenatal alcohol exposure. Presented here are the MRI assessments that were used to compare the sizes of brain regions between the 4 groups. The neuropsychological/behavioral, MRS, and fMRI outcomes are reported separately.

RESULTS

Progressing across the 4 study groups from Controls to ND/AE to SE/AE to FAS/PFAS, the mean absolute size of the total brain, frontal lobe, caudate, putamen, hippocampus, cerebellar vermis, and corpus callosum length decreased incrementally and significantly. The FAS/PFAS group (the only group with the 4-Digit FAS facial phenotype) had disproportionately smaller frontal lobes relative to all other groups. The FAS/PFAS and SE/AE groups [the 2 groups with the most severe central nervous system (CNS) dysfunction] had disproportionately smaller caudate regions relative to the ND/AE and Control groups. The prevalence of subjects in the FAS/PFAS, SE/AE, and ND/AE groups that had 1 or more brain regions, 2 or more SDs below the mean size observed in the Control group was 78, 58, and 43%, respectively. Significant correlations were observed between size of brain regions and level of prenatal alcohol exposure, magnitude of FAS facial phenotype, and level of CNS dysfunction.

CONCLUSIONS

Magnetic resonance imaging provided further validation that ND/AE, SE/AE, and FAS/PFAS as defined by the FASD 4-Digit Code are 3 clinically distinct and increasingly more affected diagnostic subclassifications under the umbrella of FASD. Neurostructural abnormalities are present across the spectrum. MRI could importantly augment diagnosis of conditions under the umbrella of FASD, once population-based norms for structural development of the human brain are established.

Phenotypic plasticity of taxonomic and diagnostic structures in gyrodactylosis-causing flatworms (Monogenea, Platyhelminthes)

The present study addresses the effect of varying temperature and host species on the size and shape of the opisthaptoral hard-parts in isogenic strains of Gyrodactylus salaris and G. thymalli. Variation in shape was examined using geometric morphometrics. Since the opisthaptoral hard-parts of Gyrodactylus have few specific landmarks, their shape information mostly being represented by outlines and surfaces, a method based on sliding semi-landmarks was applied. The ventral bars of G. salaris did not follow the previously postulated negative correlation between size and temperature, and the largest hamuli and marginal hooks from G. salaris and the smallest from G. thymalli clearly overlapped in size. Consistent shape differences with temperature were detected for the hard-parts from G. thymalli but not from G. salaris. The hard-parts of G. salaris were similar in size but significantly different in shape when grown on secondary hosts rather than the primary host.

A review of the verbal and visual memory impairments in children with foetal alcohol spectrum disorders

BACKGROUND

Children with Foetal Alcohol Spectrum Disorders (FASD) have significant impairments in memory, negatively affecting academics and daily functioning.

PRIMARY OBJECTIVE

To review published research on: (1) verbal and visual-spatial memory in children with FASD or prenatal alcohol exposure (PAE); (2) animal research on the impact of PAE on memory; and (3) brain areas involved in memory that are affected by PAE.

MAIN OUTCOMES

Verbal memory is one of the main areas of memory affected by gestational alcohol exposure, specifically in encoding and retrieving information. Spatial memory has emerged as a dominant deficit in individuals with FASD, consistent in children, adolescents and adults. There are regions of the brain more typically affected by PAE, which have ties to memory functioning. Animal research has confirmed the presence of impacts to key brain regions involved in memory functioning for those affected by PAE.

CONCLUSION

Memory deficits are a prevalent finding in individuals with PAE. Research in this area is complicated by small sample sizes, difficulty linking animal research to human application and lack of effective connection between existing memory theory and functional memory testing in FASD. New research has shown that there are implications for memory and learning amelioration in children with FASD.

Microstructural corpus callosum anomalies in children with prenatal alcohol exposure: an extension of previous diffusion tensor imaging findings

BACKGROUND

Several studies have now shown corpus callosum abnormalities using diffusion tensor imaging (DTI) in children with fetal alcohol spectrum disorders (FASD) in comparison with nonexposed controls. The data suggest that posterior regions of the callosum may be disproportionately affected. The current study builds on previous efforts, including our own work, and moves beyond midline corpus callosum to probe major inter-hemispheric white matter pathways with an improved DTI tractographic method. This study also expands on our prior work by evaluating a larger sample and by incorporating children with a broader range of clinical effects including full-criteria fetal alcohol syndrome (FAS).

METHODS

Participants included 33 children with FASD (8 FAS, 23 partial FAS, 2 static encephalopathy) and 19 nonexposed controls between the ages of 10 and 17 years. Participants underwent DTI scans and intelligence testing. Groups (FASD vs. controls) were compared on fractional anisotropy (FA) and mean diffusivity (MD) in 6 white matter tracts projected through the corpus callosum. Exploratory analyses were also conducted examining the relationships between DTI measures in the corpus callosum and measures of intellectual functioning and facial dysmorphology.

RESULTS

In comparison with the control group, the FASD group had significantly lower FA in 3 posterior tracts of the corpus callosum: the posterior mid-body, the isthmus, and the splenium. A trend-level finding also suggested lower FA in the genu. Measures of white matter integrity and cognition were correlated and suggest some regional specificity, in that only posterior regions of the corpus callosum were associated with visual-perceptual skills. Correlations between measures of facial dysmorphology and posterior regions of the corpus callosum were nonsignificant.

CONCLUSIONS

Consistent with previous DTI studies, these results suggest that microstructural posterior corpus callosum abnormalities are present in children with prenatal alcohol exposure and cognitive impairment. These abnormalities are clinically relevant because they are associated with cognitive deficits and appear to provide evidence of abnormalities associated with prenatal alcohol exposure independent of dysmorphic features. As such, they may yield important diagnostic and prognostic information not provided by the traditional facial characteristics.

Optic disc morphology--rethinking shape

Morphometrics, a branch of morphology, represents the study of size and shape components of biological form and their variation in the population. Assessment of optic disc morphology is essential in the diagnosis and management of many ophthalmic disorders. Much work has been performed to characterize size-related parameters of the optic disc; however, limited information is available on shape variation in the general population. In contrast to optic disc or cup sizes, which are conceptually meaningful variables with a defined unit of measurement, there are few metric constructs by which to quantify, visualize and interpret variation in optic disc or cup shape. This has significance in ophthalmic diseases with a genetic basis as recent evidence has suggested that optic disc shape may be heritable. Conventional optic disc shape measures of 'ovality' and 'form-factor' reduce a complex structure to a single number and eliminate information of potential diagnostic relevance from further analyses. The recent advent of 'geometric morphometrics', a branch of statistics that incorporates tools from geometry, biometrics and computer graphics in the quantitative analysis of biological forms, has enabled spatial relationships in shape data to be retained during analysis. The analytical methods employed in geometric morphometrics can be separated into two distinct groups: landmark-based (e.g. Procrustes analysis, thin-plate splines) and boundary outline techniques (e.g. Fourier analysis). In this review, we summarize current approaches to the study of optic disc morphology, discuss the underlying theory of geometric morphometrics within the context of analytical techniques and then explore the contemporary relevance of the subject matter to several biological fields. Finally we illustrate the potential application of geometric morphometrics to the specific problem of optic disc shape and glaucoma assessment.

Prenatal alcohol exposure and interhemispheric transfer of tactile information: Detroit and Cape Town findings

BACKGROUND

Previous research has demonstrated that heavy prenatal alcohol exposure affects the size and shape of the corpus callosum (CC) and compromises interhemispheric transfer of information. The aim of this study was to confirm the previous reports of poorer performance on a finger localization test (FLT) of interhemispheric transfer in a cohort of heavily exposed children and to extend these findings to a cohort of moderately exposed young adults.

METHODS

In Study 1, the FLT was administered to 40 heavily exposed and 23 nonexposed children from the Cape Coloured community of Cape Town, South Africa, who were evaluated for fetal alcohol syndrome (FAS) dysmorphology and growth. Anatomical images of the CC were obtained using structural MRI on a subset of these children. In Study 2, the FLT was administered to a cohort of 85 moderate-to-heavily exposed young adults participating in a 19-year follow-up assessment of the Detroit Prenatal Alcohol Exposure cohort, whose alcohol exposure had been ascertained prospectively during gestation.

RESULTS

In Study 1, children with FAS showed more transfer-related errors than controls after adjustment for confounding, and increased transfer-related errors were associated with volume reductions in the isthmus and splenium of the CC. In Study 2, transfer-related errors were associated with quantity of alcohol consumed per occasion during pregnancy. More errors were made if the mother reported binge drinking (> or =5 standard drinks) during pregnancy than if she drank regularly (M > or = 1 drink/day) without binge drinking.

CONCLUSIONS

These findings confirm a previous report of impaired interhemispheric transfer of tactile information in children heavily exposed to alcohol in utero and extend these findings to show that these deficits are also seen in more moderately exposed individuals, particularly those exposed to binge-like pregnancy drinking.

Neuroimaging of children following prenatal drug exposure

Recent advances in MR-based brain imaging methods have provided unprecedented capabilities to visualize the brain. Application of these methods has allowed identification of brain structures and patterns of functional activation altered in offspring of mothers who used licit (e.g., alcohol and tobacco) and illicit (e.g., cocaine, methamphetamine, and marijuana) drugs during pregnancy. Here we review that literature, which though somewhat limited by the complexities of separating the specific effects of each drug from other confounding variables, points to sets of interconnected brain structures as being altered following prenatal exposure to drugs of abuse. In particular, dopamine-rich cortical (e.g., frontal cortex) and subcortical (e.g., basal ganglia) fetal brain structures show evidence of vulnerability to intrauterine drug exposure suggesting that during brain development drugs of abuse share a specific profile of developmental neurotoxicity. Such brain malformations may shed light on mechanisms underlying prenatal drug-induced brain injury, may serve as bio-markers of significant intrauterine drug exposure, and may additionally be predictors of subsequent neuro-developmental compromise. Wider clinical use of these research-based non-invasive methods will allow for improved diagnosis and allocation of therapeutic resources for affected infants, children, and young adults.

Foetal Alcohol Spectrum Disorders and alterations in brain and behaviour

The term 'Foetal Alcohol Spectrum Disorders (FASD)' refers to the range of disabilities that may result from prenatal alcohol exposure. This article reviews the effects of ethanol on the developing brain and its long-term structural and neurobehavioural consequences. Brain imaging, neurobehavioural and experimental studies demonstrate the devastating consequences of prenatal alcohol exposure on the developing central nervous system (CNS), identifying specific brain regions affected, the range of severity of effects and mechanisms involved. In particular, neuroimaging studies have demonstrated overall and regional volumetric and surface area reductions, abnormalities in the shape of particular brain regions, and reduced and increased densities for white and grey matter, respectively. Neurobehaviourally, FASD consists of a continuum of long-lasting deficits affecting multiple aspects of cognition and behaviour. Experimental studies have also provided evidence of the vulnerability of the CNS to the teratogenic effects of ethanol and have provided new insight on the influence of risk factors in the type and severity of observed brain abnormalities. Finally, the potential molecular mechanisms that underlie the neuroteratological effects of alcohol are discussed, with particular emphasis on the role of glial cells in long-term neurodevelopmental liabilities.

Neuroimaging and fetal alcohol spectrum disorders

The detrimental effects of prenatal alcohol exposure on the developing brain include structural brain anomalies as well as cognitive and behavioral deficits. Initial neuroimaging studies of fetal alcohol spectrum disorders (FASD) using magnetic resonance imaging (MRI) confirmed previous autopsy reports of overall reduction in brain volume and central nervous system (CNS) disorganization, with specific structural abnormalities of the corpus callosum, cerebellum, caudate, and hippocampus. Advances in neuroimaging techniques have allowed detection of regional increases in cortical thickness and gray matter volume along with decreased volume and disorganization of white matter in individuals with FASD. In addition, functional imaging studies have found functional and neurochemical differences in those prenatally exposed to alcohol. Behavioral alterations noted in individuals with FASD are consistent with the findings noted in the brain imaging studies. Continued neuroimaging studies are needed to further advance understanding of the neuroteratogenic effects of alcohol.

Peptidergic agonists of activity-dependent neurotrophic factor protect against prenatal alcohol-induced neural tube defects and serotonin neuron loss

INTRODUCTION

Prenatal alcohol exposure via maternal liquid diet consumption by C57BL/6 (B6) mice causes conspicuous midline neural tube deficit (dysraphia) and disruption of genesis and development of serotonin (5-HT) neurons in the raphe nuclei, together with brain growth retardation. The current study tested the hypothesis that concurrent treatment with either an activity-dependent neurotrophic factor (ADNF) agonist peptide [SALLRSIPA, (SAL)] or an activity-dependent neurotrophic protein (ADNP) agonist peptide [NAPVSIPQ, (NAP)] would protect against these alcohol-induced deficits in brain development.

METHODS

Timed-pregnant B6 dams consumed alcohol from embryonic day 7 (E7, before the onset of neurulation) until E15. Fetuses were obtained on E15 and brain sections processed for 5-HT immunocytochemistry, for evaluation of morphologic development of the brainstem raphe and its 5-HT neurons. Additional groups were treated either with SAL or NAP daily from E7 to E15 to assess the potential protective effects of these peptides. Measures of incomplete occlusion of the ventral canal and the frequency and extent of the openings in the rhombencephalon were obtained to assess fetal dysraphia. Counts of 5-HT-immunostained neurons were also obtained in the rostral and caudal raphe.

RESULTS

Prenatal alcohol exposure resulted in abnormal openings along the midline and delayed closure of ventral canal in the brainstem. This dysraphia was associated with reductions in the number of 5-HT neurons both in the rostral raphe nuclei (that gives rise to ascending 5-HT projections) and in the caudal raphe (that gives rise to the descending 5-HT projections). Concurrent treatment of the alcohol-consuming dams with SAL prevented dysraphia and protected against the alcohol-induced reductions in 5-HT neurons in both the rostral and caudal raphe. NAP was less effective in protecting against dysraphia and did not protect against 5-HT loss in the rostral raphe, but did protect against loss in the caudal raphe.

CONCLUSIONS

These findings further support the potential usefulness of these peptides for therapeutic interventions in pregnancies at risk for alcohol-induced developmental deficits. Notably, the ascending 5-HT projections of the rostral raphe have profound effects in regulating forebrain development and function, and the descending 5-HT projections of the caudal raphe are critical for regulating respiration. Protection of the rostral 5-HT-system may help prevent structural and functional deficits linked to abnormal forebrain development, and protection of the caudal systems may also reduce the increased risk for sudden infant death syndrome associated with prenatal alcohol exposure.

Age and gender differences in response to neonatal ethanol withdrawal and polyamine challenge in organotypic hippocampal cultures

BACKGROUND

Polyamines are synthesized and released in high concentrations during CNS development. These agents can potentiate N-methyl-D-aspartate receptor (NMDAR) function and appear to play an important role in CNS development. Previous work has shown that polyamine release is increased during ethanol withdrawal (EWD). This likely promotes NMDAR overactivity and contributes to neurotoxicity during EWD, however, little is known regarding such effects in early neonatal brain. The present study compared the effects of EWD and polyamine exposure on toxicity in hippocampal slice cultures derived from postnatal day 2 (PND 2) or postnatal day 8 (PND 8) day-old rats. Due to changes in NMDAR subtypes and response to polyamines, we predicted that slices taken from PND 2 pups would be more sensitive to EWD and polyamine challenge.

METHODS

Organotypic hippocampal slice cultures were obtained from neonatal rats either 2 or 8 days of age (PND 2 or PND 8). Five days after explantation, cultures were exposed to ETOH (50 mM- typically subthreshold for EWD induced cell death) for 10 days and then withdrawn from ETOH for 24-hour in the presence of 100 microM of the polyamine spermidine and/or 100 microM ifenprodil, an NMDAR antagonist that blocks the NMDAR that is the most sensitive to polyamine modulation. Cytotoxicity was measured after 24-hour by visualization of propidium iodide (PI) fluorescence.

RESULTS

There were clear age and gender-dependent differences in response to EWD and to polyamines. EWD produced significant increases in PI uptake in all subregions (CA1, CA3 and DG) of cultures derived from PND 2 pups, but not PND 8 pups. Exposure of cultures to spermidine for 24-hour also produced significant increases in cytotoxicity in all 3 regions of PND 2 cultures with no gender differences. In contrast, there were both gender and region-specific differences in response to spermidine in cultures from PND 8. While the CA1 region of both sexes displayed increased cytotoxicity following spermidine exposure, only females showed increased cytotoxicity in the CA3 region while the DG appeared relatively insensitive to spermidine. Exposure to spermidine during EWD produced enhanced toxicity in all 3 hippocampal subregions in tissue from both PND 2 and PND 8 rats and this was reduced or prevented by co-exposure to ifenprodil. Of interest, the PND 2 hippocampus was significantly more sensitive than the PND 8 hippocampus to the toxic effects of EWD and to spermidine during EWD in the DG and CA3 regions.

CONCLUSIONS

Hippocampal slice cultures derived from PND 2 rats were more sensitive to the toxic effects of both EWD and EWD + spermidine exposure than were those derived from PND 8 rats. These findings are similar to recent behavioral data collected from our lab showing greater sensitivity to ETOH's behavioral teratogenic effects when ETOH exposure in vivo occurred during the first postnatal week relative to the second postnatal week. Ifenprodil's ability to block the toxic effects of spermidine during EWD suggests that excess activity of NR2B subunits of the NMDAR contributed to the excitatory and cytotoxic effects of EWD plus spermidine. While no sex differences in toxicity were observed in cultures taken from pups during the first postnatal week, these data do suggest that later in neonatal life (i.e., the second postnatal week), the female hippocampus may be more sensitive to polyamine-induced neurotoxicity than males.

Evidence of rapid ongoing brain development beyond 2 years of age detected by fiber tracking

BACKGROUND AND PURPOSE

Development of callosal fibers is important for psychomotor and cognitive functions. We hypothesized that brain maturation changes are detectable beyond 2 years of age by using diffusion tensor imaging (DTI) of the corpus callosum (CC).

MATERIALS AND METHODS

T2 and fractional anisotropy (FA) maps of the brain of 55 healthy subjects between 0.2 and 39 years of age were obtained. Quantitative T2 and FA values were measured at the genu and splenium of the CC (gCC and sCC). Fiber tracking, volumetric determination, and the fiber density calculations of the CC were related to age. A paired t test was used for significant differences between the values at the gCC and sCC.

RESULTS

T2 relaxation times at gCC and sCC decrease fast in the first months of life and very little after 2 years of age. The FAgCC increases until 5 years of age and remains nearly constant thereafter; it showed a significant increase from 0 to 2 years versus 2-5 years, whereas there was no difference in the other age groups. FAsCC values showed no significant changes after 2 years of age. The fiber density of the CC shows a tendency of inverse age dependence from childhood to adulthood.

CONCLUSION

Rapid ongoing changes in brain maturation (increase in FAgCC) are detectable until 5 years of age. DTI reveals more information about brain maturation than T2 relaxometry.

Mapping white matter integrity and neurobehavioral correlates in children with fetal alcohol spectrum disorders

Brain structural abnormalities and neurocognitive dysfunction have been observed in individuals with fetal alcohol spectrum disorders (FASDs). Little is known about how white matter integrity is related to these functional and morphological deficits. We used a combination of diffusion tensor and T1-weighted magnetic resonance imaging to evaluate white matter integrity in individuals with FASDs and related these findings to neurocognitive deficits. Seventeen children and adolescents with FASDs were compared with 19 typically developing age- and gender-matched controls. Lower fractional anisotropy (FA) was observed in individuals with FASDs relative to controls in the right lateral temporal lobe and bilaterally in the lateral aspects of the splenium of the corpus callosum. White matter density was also lower in some, but not all regions in which FA was lower. FA abnormalities were confirmed to be in areas of white matter in post hoc region of interest analyses, further supporting that less myelin or disorganized fiber tracts are associated with heavy prenatal alcohol exposure. Significant correlations between performance on a test of visuomotor integration and FA in bilateral splenium, but not temporal regions were observed within the FASD group. Correlations between the visuomotor task and FA within the splenium were not significant within the control group, and were not significant for measures of reading ability. This suggests that this region of white matter is particularly susceptible to damage from prenatal alcohol exposure and that disruption of splenial fibers in this group is associated with poorer visuomotor integration.

Occipital-temporal Reduction and Sustained Visual Attention Deficit in Prenatal Alcohol Exposed Adults

Visual attention problems have been reported in association with prenatal alcohol exposure (PAE). With related behavioral data documented in literature, further investigation of this PAE effect would benefit from integrating functional and anatomical imaging data to ascertain its neurobiological basis. The current study investigated the possible functional and anatomical bases for the PAE-related visual sustained attention deficit. Functional magnetic resonance imaging (fMRI) data were collected while the subjects performed a sustained visual attention task. High resolution, three dimensional anatomical images were also collected for morphometric evaluation. In the alcohol-affected subjects, we observed a significant white and gray matter volume reduction in the occipital-temporal area. Meanwhile, their fMRI activations in the same region resided more superiorly than that of the controls resulting in reduced activation in the ventral occipital-temporal area. The location of this PAE functional abnormality approximately matches that of the significant structural reduction. In addition to the well documented corpus callosum abnormalities observed in PAE subjects, the present results reveal a teratogenic effect on the occipital-temporal area. Furthermore, as the occipital-temporal area plays an important role in visual attention, the current observation suggests a neurobiological underpinning for the PAE related deficit in sustained visual attention.

Perfil de habilidades de comunicação de dois irmãos com a Síndrome Alcoólica Fetal

OBJETIVO: caracterizar o perfil de habilidades de comunicação e o desempenho nos subtestes do Teste Illinois de Habilidades Psicolingüísticas (ITPA) de dois irmãos com diagnóstico da Síndrome Alcoólica Fetal (SAF): S1, sexo feminino, 16 anos e S2, sexo masculino, 8 anos, alunos de escola especial. MÉTODOS: realizou-se a avaliação fonoaudiológica clínica, complementada pela aplicação do ITPA. RESULTADOS: dados de avaliação clínica com S1 mostraram prejuízo grave de compreensão oral, não sendo capaz de seguir instruções (verbal e gestual) simples. Também não se observou uso de recursos gestuais ou orais, por parte da mesma para se comunicar. Devido ao nível de comprometimento, não foi possível obter dados relativos aos desempenhos amostrados no ITPA. Dados de avaliação clínica com S2 mostraram resultados bastante diferentes. S2 utiliza preferencialmente a fala para se comunicar, responde perguntas, mantendo o tema e é capaz de seguir instruções verbais simples. Entretanto, observou-se desempenho inferior ao esperado para idade em situações que requeriam narrativa de fatos e eventos, indicando prejuízos em aspectos sintáticos e semânticos da linguagem. No ITPA obteve pontuação inferior a idade cronológica em quase todos os subtestes. O pior desempenho foi observado nos subtestes que envolviam habilidades perceptivas auditivas. CONCLUSÕES: esses resultados indicam que, apesar de ambos terem o mesmo diagnóstico genético e viverem sob as mesmas condições familiares, o perfil fonoaudiológico difere. Pode-se especular que prejuízos mais graves em habilidades comunicativas de S1 podem estar relacionados a níveis mais elevados de exposição ao álcool durante etapas críticas do desenvolvimento fetal.

The influence of artificial cranial vault deformation on the expression of cranial nonmetric traits: its importance in the study of evolutionary relationships

Nonmetric cranial traits have been commonly used in evolutionary relationship studies. They develop during the growth and development of an individual, and for this reason its expression presents different sources of genetic and nongenetic variation. However, the use of these features in evolutionary relationship studies carries the implicit assumption that much of the nonmetric trait variation is essentially genetic. Among the nonheritable factors, cranial vault deformation has been the most studied in human populations. Because of the widespread distribution and elevated rate of artificial cranial vault deformation found in America, and the importance of nonmetric traits in evolutionary relationship studies in this area, the objectives of this paper are as follows: (a) to study the influence of artificial cranial vault deformation on the presence of nonmetric traits within samples of human craniofacial remains; and (b) to establish artificial cranial vault deformation influence on evolutionary relationships between local populations on a regional scale. Our results indicate that artificial cranial vault deformations alter the variation and covariation of metric and nonmetric traits in some samples. Wormian bones, placed in cranial vault sutures, are the most influenced by this factor. However, our results suggest that when all nonmetric traits were used the artificial cranial vault deformation did not influence the basic pattern of variation among samples. The exclusion or inclusion of wormians bones in evolutionary relationships analysis did not modify the results, but using only wormians bones lead to inconsistent results indicating that these traits have little value on these kind of studies.

Analysis of experimental cranial skin wounding from screwdriver trauma

As part of a more extensive investigation of skin wounding mechanisms, we studied wounds created by five common screwdrivers (straight, star, square or Robertson, Posidriv and Phillips) on the shaven foreheads of 12 freshly slaughtered pigs. We fixed the different screwdriver heads to a 5-kg metal cylinder which was directed vertically onto each pig head by a droptube of 700 mm length. We examined skin lesions by photography and also by scanning electron microscopy (SEM). Our evaluation of differences in wound shape and size was based on geometric morphometric methods. Our results show that there are obvious morphological differences between the straight head and the other types. The straight-headed screwdriver penetrates the skin by a mode II crack which results in a compressed skin plug with bundles of collagen fibres forming skin tabs within the actual wound. The sharper-tipped screwdrivers wedge open the skin (mode I), with a clearly defined edge with no skin plugs. Geometric morphometric analysis indicates that shapes of skin wounds created by the five screwdriver types could be classified into three different groups. The straight head results in the most differentiated wound profile, with the Robertson or square and some specimens of star, and also the Posidriv and Phillips giving similar wound outlines. SEM evaluation of wounds created by a new and worn straight-head screwdrivers shows that the outline of the worn screwdriver head is reflected in the shape of the wound it created.

Size and shape analysis of human molars: comparing traditional and geometric morphometric techniques

Dental size and shape have been widely used to study biological relationships among human populations. Although several techniques have been proposed to quantify dental form, few attempts have been made to compare results obtained by application of different techniques. This work aims at comparing the information about size and shape of molar contours obtained from linear measurements, landmarks and semi-landmarks as well as evaluating the variation patterns among populations obtained by each method. The crowns of 35 permanent upper second molars belonging to archaeological samples from three regions of Argentina were analyzed. Buccolingual and mesiodistal crown diameters were measured and centroid size and crown index were used as size and shape descriptors, respectively. Likewise, four landmarks and 79 semi-landmarks were collected from the molar outline and relative warps (RW) analysis was performed on partial warps and uniform vectors; centroid size was estimated to summarize tooth size. The results indicate that size was consistently estimated by the three variable types. On the contrary, noticeable differences were found when the results of molar shape described by linear measurements were compared with those obtained using either landmarks or semi-landmarks. This study shows that considerable information about molar contour is added by using landmarks instead of crown diameters and that some morphological features, such as degree of cusp development, can only be captured by means of semi-landmark analysis. Finally, the interpretation of similarities among samples differs according to the selected description system.

The Uniqueness of the Human Anterior Dentition: A Geometric Morphometric Analysis

The analysis of bitemarks has a significant bearing on forensic odontology and has attracted an increasingly sophisticated array of techniques in its evaluation. Two postulates underlie all bitemark analyses: firstly, that the characteristics of the anterior teeth involved in the bite are unique, and secondly, that this uniqueness is accurately recorded in the material bitten. Here, we investigate the question of the uniqueness of the anterior dentition. To do this, we use geometric morphometric techniques based on landmark and semilandmark data. The incisor and canine occlusal surfaces of 50 randomly selected orthodontic casts of young individuals (17-20 years) of both sexes form the material for this study. We analyzed the sizes of these teeth by means of landmark and semilandmark analysis to calculate Procrustes distances between tooth outlines. In order to analyze shape variation among individuals, we carried out principal components analyses on the partial warp scores. These are derived from Partial Procrustes coordinates aligned by means of thin-plate spline decomposition based on the bending energy matrix. The results indicate that there is no sexual dimorphism in the shape of the upper or lower arches. Plots of centroid size and first relative warps show less superposition among individuals than in shape analysis. This means that, when the size and shape are considered together, the difference between arches increases. Procrustes superimposition between the two individuals located most closely (0.0444) and the two most separated (0.1567) along the first axis of relative warp analyses show that individuals are not only differentiated by the relative position of their teeth but also by their arch shape. In conclusion, it appears that the incisal surfaces of the anterior dentition are in fact unique.

Abnormal cortical thickness and brain-behavior correlation patterns in individuals with heavy prenatal alcohol exposure

Quantitative magnetic resonance imaging (MRI) studies in children with fetal alcohol spectrum disorders (FASDs) have shown regional patterns of dysmorphology, most prominent in parietal and posterior temporal cortices. Various methods of image analysis have been employed in these studies, but abnormalities in cortical thickness have not yet been mapped over the entire cortical surface in individuals with FASD. Further, relationships between cognitive dysfunction and cortical thickness measures have not yet been explored. We applied cortical pattern matching algorithms and techniques for measuring cortical thickness in millimeters to the structural brain MRI images of 21 subjects with heavy prenatal alcohol exposure (8-22 years, mean age 12.6 years), and 21 normally developing control subjects (8-25 years, mean age 13.5 years). Dissociable cognitive measures, of verbal recall and visuospatial functioning, were correlated with cortical thickness, and group by test score interactions were evaluated for predicting cortical thickness. Significant cortical thickness excesses of up to 1.2 mm were observed in the FASD subjects in large areas of bilateral temporal, bilateral inferior parietal, and right frontal regions. Significant group by test score interactions were found in right dorsal frontal regions for the verbal recall measure and in left occipital regions for the visuospatial measure. These results are consistent with earlier analyses from our own and other research groups, but for the first time, we show that cortical thickness is also increased in right lateral frontal regions in children with prenatal alcohol exposure. Further, the significant interactions show for the first time that brain-behavior relationships are altered as a function of heavy prenatal alcohol exposure.

Many infants prenatally exposed to high levels of alcohol show one particular anomaly of the corpus callosum

INTRODUCTION

Effects of prenatal alcohol exposure on the brain are seen at every age. The earlier they can be quantified, the better the prognosis for the affected child. Here we show measurable alcohol effects at birth on a structure currently used for nosology only much later in life.

METHODS

Midline shape of the corpus callosum was imaged in infants via averaged unwarped transfontanelle ultrasound. We compared measures of these shapes among 23 infants prenatally exposed to high levels of alcohol and 21 infants unexposed to alcohol or only lightly exposed.

RESULTS

A particular feature of the corpus callosum, the appearance of a "hook" (obtuse angle) between the splenium and the long diameter of the arch in this plane, is strongly associated with prenatal alcohol exposure. In half of the high-exposed infants, the splenium angle is larger than in any of the unexposed brains. Simply characterizing this angle as less than or greater than 90 degrees detects 12 of the 23 exposed infants as anomalous with only 1 false positive among the unexposed. This apparently direct effect of prenatal ethanol exposure on the details of the callosum in about half the at-risk subjects cannot be attributed to any of several plausible competing exposures or other confounding factors applying during or after gestation.

CONCLUSION

An average of the images for the unexposed subjects has the geometry of textbook images of normal babies; but the average for the subgroup of high-angle subjects may serve as a template or guide to this regional damage parallel to the familiar photographic exemplars that help to assess facial signs.

Damage to the human cerebellum from prenatal alcohol exposure: the anatomy of a simple biometrical explanation

Since 1973, it has become clear that exposure of otherwise normal human fetuses to high levels of alcohol damages a substantial number of the exposed brains in a wide variety of ways nowadays referred to collectively as the fetal alcohol spectrum disorders (FASDs). Averages of images and measurements of brains with these disorders are quantitatively different from normal, and the cerebellum is one of the structures at which differences are typically noted. The present article extends these techniques to a simple, practical, and enlightening detection rule for fetal alcohol damage in adolescents and adults known to have been heavily exposed. The data arise from 180 clinical MR brain images (half of adolescents, half of adults; half male, half female; one-third each fetal alcohol syndrome, fetal alcohol effects, and unexposed). The 180 cerebellums were represented by 328-semilandmark triangulations covering most of the cerebellar surface. Statistical analysis exploited the now-conventional methods of Procrustes analysis in three dimensions, along with a recent extension to incorporate size information explicitly. If we reduce the data complexity even further, to just 23 points along the silhouette of the cerebellum as viewed from above along the aqueductal axis, the analysis becomes more precise. Now a single multivariate summary score, very strongly correlated with size, supports a discrimination (diagnosed vs. unexposed) with about 75% accuracy. About one-quarter of our FASD sample overlaps with the central range of the unexposed in the distribution of this size-based score, with the other three-quarters distinctly showing cerebellar damage. The finding, which corresponds quite closely to the fundamental finding of cerebellar hypoplasia in animal experiments, bears implications for fetal alcohol epidemiology, for geometric morphometrics, and for the geometric complexity of useful data structures derived from clinical brain imaging.

Defining the behavioral phenotype in children with fetal alcohol spectrum disorders: A review

While there exists a large body of literature on cognitive functions in children with prenatal alcohol exposure, it remains undetermined if these children exhibit a unique profile of cognitive-behavioral functioning or a behavioral phenotype. Researchers have consistently found that intellectual functioning, as assessed by IQ tests, of children with prenatal alcohol exposure is deficient. There is increasing evidence that prenatal alcohol exposure is associated with slow information processing and attentional problems, in particular inattentiveness. Studies examining specific cognitive abilities such as language, visual perception, and memory in alcohol-affected children have shown performance decrements associated with increased task complexity. Children with prenatal alcohol exposure have also been found to exhibit significant deficits in daily functional skills or adaptive behavior, with deficits in socialization becoming pronounced during adolescence. The above findings point to the conclusion that a generalized deficit in complex information processing constitutes the central cognitive-behavioral characteristic of children with prenatal alcohol exposure. Researchers have consistently documented that specific brain regions are more affected by alcohol than other regions. The problem of mapping focal anomalies of the brain with a generalized pattern of deficits can be solved by taking developmental processes into consideration.

Morphological differentiation of aboriginal human populations from Tierra del Fuego (Patagonia): Implications for South American peopling

This study aims to integrate the craniofacial morphological variation of southern South American populations with the results of mtDNA haplogroup variation, to discuss the South America peopling. Because the causes of morphological differentiation of Fueguian populations are still a controversial subject, the comparison with neutral variation could contribute to elucidate them. Samples of human remains from South America regions were used to analyze the evolutionary relationships. Several craniofacial traits observed in frontal and lateral view were analyzed by means of geometric morphometrics techniques, and the evolutionary relationships based on morphological and molecular data were established in base to ordination analyses. The results from the facial skeleton agree with those obtained from mtDNA haplogroup frequencies, with La Pampa/Chaco samples detached from the Patagonian samples. Hence, the same mechanism that accounts for the pattern of frequency of haplogroups could explain the variation found in facial skeleton among the samples. It is suggested that such geographic pattern of craniofacial and molecular diversity may reflect the effect of genetic drift that occurred in the small founding populations isolated by distance or geographic barriers. Conversely, the results obtained using the traits from the lateral view slightly differ from the molecular results, showing differences between southernmost Patagonian and the other samples. Therefore, mechanisms other than genetic drift (e.g., natural selection) could have acted to shape the pattern observed in some craniofacial structures present in the lateral view, characterized by the fact that the southernmost Patagonian samples display the most robust and dolichocephalic crania.

Diffusion tensor imaging in children with fetal alcohol spectrum disorders

BACKGROUND

Prenatal alcohol exposure, which is associated with macrostructural brain abnormalities, neurocognitive deficits, and behavioral disturbances, is characterized as fetal alcohol syndrome (FAS) in severe cases. The only published study thus far using diffusion tensor imaging (DTI) showed microstructural abnormalities in patients with FAS. The current study investigated whether similar abnormalities are present in less severely affected, prenatally exposed patients who did not display all of the typical FAS physical stigmata.

METHODS

Subjects included 14 children, ages 10 to 13, with fetal alcohol spectrum disorders (FASD) and 13 matched controls. Cases with full-criteria FAS, mental retardation, or microcephaly were excluded. Subjects underwent MRI scans including DTI.

RESULTS

Although cases with microcephaly were excluded, there was a trend toward smaller total cerebral volume in the FASD group (p=0.057, Cohen's d effect size =0.73). Subjects with FASD had greater mean diffusivity (MD) in the isthmus of the corpus callosum than controls (p=0.013, effect size =1.05), suggesting microstructural abnormalities in this region. There were no group differences in 5 other regions of the corpus callosum. Correlations between MD in the isthmus and facial dysmorphology were nonsignificant.

CONCLUSIONS

These results suggest that even relatively mild forms of fetal alcohol exposure may be associated with microstructural abnormalities in the posterior corpus callosum that are detectable with DTI.

Brain Metabolic Alterations in Adolescents and Young Adults With Fetal Alcohol Spectrum Disorders

BACKGROUND

Prenatal alcohol exposure affects brain structure and function. This study examined brain metabolism using magnetic resonance spectroscopy (MRS) and searched for regions of specific vulnerability in adolescents and young adults prenatally exposed to alcohol.

METHODS

Ten adolescents and young adults with confirmed heavy prenatal alcohol exposure and a diagnosis within the fetal alcohol spectrum disorders (FASD) were included. Three of them had fetal alcohol syndrome (FAS), 3 had partial FAS (PFAS), and 4 had alcohol-related neurobehavioral disorder (ARND). The control group consisted of 10 adolescents matched for age, sex, head circumference, handedness, and body mass. Exclusionary criteria were learning disorders and prenatal alcohol exposure. Three-dimensional (1)H magnetic resonance spectroscopic imaging ((1)H MRSI) was performed in the cerebrum and cerebellum. Metabolite ratios N-acetylaspartate/choline (NAA/Cho), NAA/creatine (Cr) and Cho/Cr, and absolute metabolite intensities were calculated for several anatomic regions.

RESULTS

In patients with FASD, lower NAA/Cho and/or NAA/Cr compared with controls were found in parietal and frontal cortices, frontal white matter, corpus callosum, thalamus, and cerebellar dentate nucleus. There was an increase in the absolute intensity of the glial markers Cho and Cr but no change in the neuronal marker NAA.

CONCLUSIONS

Our results suggest that prenatal alcohol exposure alters brain metabolism in a long-standing or permanent manner in multiple brain areas. These changes are in accordance with previous findings from structural and functional studies. Metabolic alterations represent changes in the glial cell pool rather than in the neurons.