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

Neuroimaging and fetal alcohol spectrum disorders

Heavy prenatal alcohol exposure causes permanent structural alterations to the brain and can lead to numerous cognitive and behavioral outcomes. Consistent with many of the neuropsychological and behavioral deficits that have been reported, neuroimaging studies reveal a pattern of structural abnormalities associated with prenatal alcohol exposure. This chapter systematically reviews structural anomalies by brain region, identifying cognitive and behavioral correlates when relevant. The consensus shows that in addition to the overall reduction of brain size, prominent brain shape abnormalities have been observed, with narrowing in the parietal region and reduced brain growth in portions of the frontal lobe. Commensurating with these anomalies, volumetric and tissue density findings cite disproportionate reductions in the parietal lobe, cerebellar vermis, corpus callosum, and the caudate nucleus, suggesting that certain areas of the brain may be especially vulnerable to prenatal alcohol exposure. In sum, neuroimaging techniques have greatly advanced our understanding of brain-behavior relationships in fetal alcohol spectrum disorders (FASD), and hopefully will lead to improved diagnosis and treatment options for those affected by prenatal exposure to alcohol.

Differences between sliding semi-landmark methods in geometric morphometrics, with an application to human craniofacial and dental variation

Over the last decade, geometric morphometric methods have been applied increasingly to the study of human form. When too few landmarks are available, outlines can be digitized as series of discrete points. The individual points must be slid along a tangential direction so as to remove tangential variation, because contours should be homologous from subject to subject whereas their individual points need not. This variation can be removed by minimizing either bending energy (BE) or Procrustes distance (D) with respect to a mean reference form. Because these two criteria make different assumptions, it becomes necessary to study how these differences modify the results obtained. We performed bootstrapped-based Goodall's F-test, Foote's measurement, principal component (PC) and discriminant function analyses on human molars and craniometric data to compare the results obtained by the two criteria. Results show that: (1) F-scores and P-values were similar for both criteria; (2) results of Foote's measurement show that both criteria yield different estimates of within- and between-sample variation; (3) there is low correlation between the first PC axes obtained by D and BE; (4) the percentage of correct classification is similar for BE and D, but the ordination of groups along discriminant scores differs between them. The differences between criteria can alter the results when morphological variation in the sample is small, as in the analysis of modern human populations.

Comparison of geometric morphometric outline methods in the discrimination of age-related differences in feather shape

BACKGROUND

Geometric morphometric methods of capturing information about curves or outlines of organismal structures may be used in conjunction with canonical variates analysis (CVA) to assign specimens to groups or populations based on their shapes. This methodological paper examines approaches to optimizing the classification of specimens based on their outlines. This study examines the performance of four approaches to the mathematical representation of outlines and two different approaches to curve measurement as applied to a collection of feather outlines. A new approach to the dimension reduction necessary to carry out a CVA on this type of outline data with modest sample sizes is also presented, and its performance is compared to two other approaches to dimension reduction.

RESULTS

Two semi-landmark-based methods, bending energy alignment and perpendicular projection, are shown to produce roughly equal rates of classification, as do elliptical Fourier methods and the extended eigenshape method of outline measurement. Rates of classification were not highly dependent on the number of points used to represent a curve or the manner in which those points were acquired. The new approach to dimensionality reduction, which utilizes a variable number of principal component (PC) axes, produced higher cross-validation assignment rates than either the standard approach of using a fixed number of PC axes or a partial least squares method.

CONCLUSION

Classification of specimens based on feather shape was not highly dependent of the details of the method used to capture shape information. The choice of dimensionality reduction approach was more of a factor, and the cross validation rate of assignment may be optimized using the variable number of PC axes method presented herein.

The importance of alcohol misuse, malnutrition and genetic susceptibility on brain growth and plasticity

The "dyad: alcoholic mother and foetus" is a very complex entity in which several elements such as genes, metabolism, diet, drugs and social habits play a role at different stages in the development of the fetal brain damage. The literature on the effects of alcohol consumption on the developing brain is extensive but very few evidences have been reported regarding the combined neurotoxic effects of poor nutrition and alcohol consumption. The consequences of ethanol intake alone or combined with poor maternal nutrition appear to be severe and life-long. Alcohol exerts its neurotoxic effects on the developing brain directly by acting on fetal brain tissues, and indirectly either by interfering with placental physiology or by impairing the mother's physiology. Alcohol misuse in pregnancy is also frequently associated with other conditions that can potentially increase the brain damage such as poor nutrition and smoking. This article reviews the effects of poor nutrition and alcohol misuse during pregnancy on the development of the fetal brain and discusses the cumulative effects of these two environmental factors and their interaction with maternal and fetal genetic make-ups.

The effects of moderate neonatal ethanol exposure on eyeblink conditioning and deep cerebellar nuclei neuron numbers in the rat

Heavy, bingelike patterns of exposure to ethanol during a portion of the early postnatal period in the rat, a time of rodent brain development corresponding to the human third trimester, has been shown to deplete cerebellar neurons and to produce deficits in cerebellar-dependent tasks. In the current study, we examined the impact of more moderate ethanol exposure, during an extended portion of the rat third trimester equivalent, on cerebellar-dependent learning (eyeblink conditioning) and deep cerebellar nuclei neuron numbers. Neonatal rats received 0, 1, 2, or 3g/kg/day of ethanol in milk formula via a single intragastric intubation each day across postnatal days 2-11, or were left untreated. Peak BACs for ethanol-exposed rats were 50, 150, and 225 mg/dl, respectively. Rats underwent eyeblink conditioning as young adults (70 days of age) and deep cerebellar nuclei neuron numbers were assessed at 100 days of age. In Experiment 1, all rats showed normal responsiveness to periorbital stimulation prior to conditioning. The 3-g/kg/day group was impaired in eyeblink conditioning and possessed fewer deep cerebellar nuclei neurons. A trend toward impairment was observed in the 2-g/kg/day group. However, the 0-g/kg/day group was also impaired in eyeblink conditioning. In Experiment 2, the unconditioned stimulus pretest phase was eliminated, the 0-g/kg/day group learned normally, and both the 2- and 3-g/kg/day groups were again impaired. These results suggest that more moderate doses of ethanol during the rat third-trimester equivalent can produce long-term effects on the cerebellum.

GABAergic miniature postsynaptic currents in septal neurons show differential allosteric sensitivity after binge-like ethanol exposure

Binge-like ethanol treatment of septal neurons blunts GABAAR-mediated miniature postsynaptic currents (mPSCs), suggesting it arrests synaptic development. Ethanol may disrupt postsynaptic maturation by blunting feedback signaling through immature GABAARs. Here, the impact of ethanol on the sensitivity of mPSCs to zolpidem, zinc and 3alpha-hydroxy-5alpha-pregnan-20-one (3alpha-OH-DHP) was tested. The decay phase of mPSCs showed concentration-dependent potentiation by zolpidem (0.03-100 microM), which was substantially blunted after ethanol exposure. Since zolpidem potentiation exhibited a substantial age-dependent increase in untreated neurons, this finding supported the idea that ethanol arrests synaptic development. GABAAR alpha1 subunit protein also increased with age in untreated neurons, paralleling enhanced sensitivity to zolpidem. Surprisingly, alpha1 levels were not reduced by binge ethanol even though mPSCs were relatively zolpidem-insensitive. Zinc (3-30 microM) decreased mPSC parameters in a concentration- and age-related manner with older untreated cells showing less inhibition. However, there was no increase in mPSC zinc sensitivity after binge ethanol as would be expected if a general arrest of synaptic maturation had occurred. 3alpha-OH-DHP (3-1000 nM) induced concentration-dependent potentiation of mPSC decay. Although potentiation was age-independent, binge ethanol treatment exaggerated sensitivity to this neurosteroid. Finally, chronic picrotoxin pretreatment (100 microM) intended to mimic GABAAR inhibition from ethanol pretreatment did not significantly change mPSC modulation by zolpidem, zinc or 3alpha-OH-DHP. These results suggest that binge ethanol treatment selectively arrests a subset of processes important for maturation of postsynaptic GABAA Rs. However, it is unlikely that ethanol causes a broad arrest of postsynaptic development through a direct inhibition of GABAAR signaling.

Evaluation of corpus callosum anisotropy in young adults with fetal alcohol syndrome according to diffusion tensor imaging

BACKGROUND

Fetal alcohol syndrome (FAS) and associated disorders resulting from maternal alcohol use during gestation are among the most common developmental disorders. However, they are rarely diagnosed and not fully understood in terms of their behavioral and neurocognitive phenotype. Prenatal exposure leads to alterations in facial morphology, growth, and neurocognition. The nature and extent of teratogenic effects on the brain and the relationship between such effects and observed behaviors remain in debate because there are no established markers for the neurological effects of exposure. In this study, we examined the impact of prenatal alcohol exposure on white-matter integrity in the corpus callosum by using diffusion tensor imaging (DTI) and herein describe the relationship between such effects and observed physical and behavioral outcomes.

METHODS

DTI was used to evaluate diffusion anisotropy in the genu and splenium of corpus callosum in 16 low-income, primarily African-American volunteers. Volunteers were recruited from a cohort of young adults who had received neuropsychological evaluations during adolescence. Nine had been prenatally exposed to alcohol and had characteristics of FAS, and seven were nonexposed controls.

RESULTS

Significant difference in the means for diffusion fractional anisotropy (t = 2.26, df = 9, p <0.002) and apparent diffusion coefficient (t = 2.14, df = 14, p < 0.008) were observed in the corpus callosum of alcohol-exposed youth compared with nonexposed youth. No significant differences were found in intracranial volume between these groups.

CONCLUSIONS

Our results illustrate that DTI can be used in evaluating the integrity of corpus callosum in alcohol-exposed individuals. If future studies support these findings, diffusion anisotropy, represented by fractional anisotropy, has the potential to be used as a clinical marker in the diagnosis of FAS.

Variation and causal factors of craniofacial robusticity in Patagonian hunter-gatherers from the late Holocene

Fueguian-Patagonian skulls have been characterized as some of the most robust of any modern crania. However, the causal factors of such robusticity remain unsettled. We assess within- and among-sample cranial robusticity of seven samples from continental Patagonia and Tierra del Fuego, using geometric morphometric techniques. In addition, the biomechanical, phylogenetic, and climatic hypotheses proposed to account for robusticity in such samples are discussed. Two Amerindian samples of farmers and two early middle Holocene samples from South America were included. The results show: 1) large variation in craniofacial robusticity among Patagonian samples, with the highest robusticity in samples from south continental Patagonia and Isla Grande of Tierra del Fuego, whereas central and north Patagonian samples display the same degree of robusticity as farmer samples; 2) that early middle Holocene samples display lower levels of robusticity than South Patagonian samples; and 3) strong association between latitude and craniofacial robusticity, with the most robust craniofacial morphologies occurring at the highest latitudes. In consequence, neither masticatory stress nor retention of ancestral features is supported by the morphological evidence analyzed. Hence it is hypothesized that endocrine changes related to cold climate may be a plausible explanation for several craniofacial features found in Fueguian and south continental Patagonian samples, such as their large masticatory component, and pronounced supraorbital ridge and glabellar region.

Serial neuropsychological assessment and evidence of shunt malfunction in spina bifida: a longitudinal case study

Myelomeningocele is often accompanied by hydrocephalus (MMH), making it a potentially unstable neurological condition requiring shunt placement and possible revisions. Serial neuropsychological assessment is an important tool in monitoring children with MMH, as cognitive changes can indicate shunt malfunction and hydrocephalus. We present the case of a girl with MMH who had five neuropsychological assessments (ages 5, 7, 11, 12, and 14). Despite a lack of overt neurological symptoms or report of behavioral decline, testing at age 11 revealed decline in multiple neurobehavioral domains, and imaging at that time showed increased hydrocephalus, requiring shunt revision. Subsequent neuropsychological assessment conducted after a 2-year period of medical stability showed improvement and/or a return to baseline levels in some skill areas (i.e., working memory, verbal memory, visuomotor integration, and sustained attention), yet more lasting impairments in others (i.e., Verbal IQ, processing speed, organization, and response inhibition). These lasting cognitive deficits potentially impact independent completion of complex medical self-care tasks. This pattern of recovery highlights vulnerability of brain systems supporting executive functions in children with hydrocephalus and shunt failure.

Effects of prenatal alcohol exposure on fine motor coordination and balance: A study of two adult samples

Motor coordination was assessed in two samples of adult subjects: one sample (n = 90) included adults previously diagnosed with one of a number of Fetal Alcohol Spectrum Disorders (FASD) and comparison peers, the second was a prospective longitudinal study of adults who were exposed to varying levels of alcohol as fetuses (n = 402). This comparative analysis sought to determine whether motor effects seen in both clinical and nonclinical children persist into adulthood, whether any individual motor tasks show significant effects of prenatal alcohol exposure across the age range, and whether motor assessments of adults have any role in diagnostic strategies for adults suspected of FASD. Motor tests included balance and unilateral, bilateral, finger, hand and foot coordination. Three-quarters of the subjects with FASD demonstrated deficits in motor function outside the range of comparison subjects. Adults with FASD performed more poorly, on average, on all individual tests including balance and fine motor control. In the prospective longitudinal sample, only subjects who had been previously identified in childhood as having a possible diagnosis on the Fetal Alcohol Spectrum were still in deficit as adults on motor tasks, relative to comparison subjects. Thus, the dose-dependent motor coordination effects of alcohol previously found in children do not appear to persist into adulthood, except in those most highly exposed children who also have other accompanying neuropsychological effects in childhood.

DTI tractography based parcellation of white matter: application to the mid-sagittal morphology of corpus callosum

Morphology of the corpus callosum (CC) at the mid-sagittal level has been a target of extensive studies. However, the lack of internal structures and its polymorphism make it a challenging task to quantitatively analyze shape differences among subjects. In this paper, diffusion tensor Imaging (DTI) and tract tracing technique were applied to incorporate cortical connectivity information to the morphological study. The CC was parcellated into six major subdivisions based on trajectories to different cortical areas. This subdivision was performed for eight normal subjects and one stroke patient. The parcellated CCs of the normal subjects were normalized for morphological analysis. When comparing the stroke patient to the normal population, we detected significant atrophy in the motor and sensory areas of the patient CC, in line with the clinical deficits. This approach provides a new tool to investigate callosal morphology and functional relationships.

Preliminary evidence that prenatal alcohol damage may be visible in averaged ultrasound images of the neonatal human corpus callosum

Brain damage consequent to prenatal alcohol exposure can be detected by measurements of the corpus callosum in the midline magnetic resonance (MR) brain image in adolescents and adults. The present article extends this finding into the neonatal period, when the power of detection to ameliorate the quality of the child's future life is greatest. The midline corpus callosum of the very young infant can be located reliably in multiple frames of clinical transfontanelle ultrasound. We studied a sample of 18 children aged 17 weeks or less, 7 of whom were exposed to high levels of alcohol prenatally and 11 of whom were not exposed or only minimally exposed. The midline callosum of each child was imaged up to 50 times by a standard clinical device, and coplanar subsets of these series were averaged with reference to fiducial image structures. On each average image four semilandmark points were set and their configuration quantified by standard landmark methods. The angle between the terminal bulb of splenium and the long axis of the callosal outline classifies four of the seven exposed infants as different from all 11 of the unexposed infants. This simple angle measurement upon averaged ultrasound images of the human neonatal midline corpus callosum, perhaps a version of the long-sought "biomarker of prenatal alcohol damage," may be able to discriminate baby brains affected by prenatal alcohol exposure from those that were unaffected.

Vitamin E does not protect against neonatal ethanol-induced cerebellar damage or deficits in eyeblink classical conditioning in rats

BACKGROUND

Rodent studies have shown that heavy binge-like ethanol (EtOH) exposure during the brain growth spurt [postnatal days (PD) 4-9] causes cerebellar neuronal loss and deficits in cerebellar-mediated eyeblink classical conditioning (ECC). Oxidative stress has been implicated in EtOH-mediated brain damage, and studies using vitamin E have reported amelioration of EtOH-induced tissue damage, including protection in rats against EtOH-induced cerebellar Purkinje cell (PC) loss on PD 4 to 5. The purpose of this study was to determine whether dietary supplementation with vitamin E concurrent with binge EtOH exposure on PD 4 to 9 in rats would attenuate the cerebellar cell death and ECC deficits.

METHODS

Rat pups were given one of five different neonatal treatments: (1) intubation with EtOH in milk formula (twice daily, total dose 5.25 g/kg/day), (2) intubation with EtOH in milk formula supplemented with vitamin E (12.26 mg/kg/feeding), (3) intubation with milk formula that contained vitamin E only, (4) sham intubations, or (5) normally reared unintubated controls. Between PD 26 and 33, subjects received short-delay ECC for 3 consecutive days. Unbiased stereological cell counts were performed on cerebellar PCs of left cerebellar lobules I to VI and neurons of the interpositus nucleus. In a separate study with PD 4 pups, the effects of vitamin E on EtOH-induced expression of caspase-3 active subunits were assessed using Western blot analysis.

RESULTS

EtOH-treated groups showed significant deficits in acquisition of conditioned eyeblink responses and reductions in cerebellar PCs and interpositus nucleus neurons compared with controls. Vitamin E supplementation failed to protect against these deficits. Vitamin E also failed to protect against increases in caspase-3 active subunit expression induced by acute binge EtOH exposure on PD 4.

CONCLUSIONS

In contrast to the previously reported neuroprotective potential of antioxidants on EtOH-mediated cerebellar damage, vitamin E supplementation did not diminish EtOH-induced structural and functional damage to the cerebellum in this model of binge EtOH exposure during the brain growth spurt in rats.

White matter development during childhood and adolescence: a cross-sectional diffusion tensor imaging study

Maturation of brain white matter pathways is an important factor in cognitive, behavioral, emotional and motor development during childhood and adolescence. In this study, we investigate white matter maturation as reflected by changes in anisotropy and white matter density with age. Thirty-four children and adolescents aged 6-19 years received diffusion-weighted magnetic resonance imaging scans. Among these, 30 children and adolescents also received high-resolution T1-weighed anatomical scans. A linear regression model was used to correlate fractional anisotropy (FA) values with age on a voxel-by-voxel basis. Within the regions that showed significant FA changes with age, a post hoc analysis was performed to investigate white matter density changes. With increasing age, FA values increased in prefrontal regions, in the internal capsule as well as in basal ganglia and thalamic pathways, the ventral visual pathways, and the corpus callosum. The posterior limb of the internal capsule, intrathalamic connections, and the corpus callosum showed the most significant overlaps between white matter density and FA changes with age. This study demonstrates that during childhood and adolescence, white matter anisotropy changes in brain regions that are important for attention, motor skills, cognitive ability, and memory. This typical developmental trajectory may be altered in individuals with disorders of development, cognition and behavior.

Interactive Effect of Alcohol and Nicotine on Developing Cerebellum: An Investigation of the Temporal Pattern of Alcohol and Nicotine Administration

BACKGROUND

Among individuals who use alcohol and tobacco products, pregnant women represent a unique subpopulation that generates a greater concern because of the toxic effects of alcohol and nicotine (from cigarettes and tobacco products) on the health of both the pregnant woman and her fetus. Therefore, it is imperative to understand the interactive effects of these two substances on the fetus. Previously, we found that concurrent exposure to alcohol and nicotine did not result in the loss of greater numbers of Purkinje cells compared with each drug treatment alone, possibly as a result of a nicotine-mediated decline in peak blood alcohol concentration (BAC). The present study tested the validity of this hypothesis.

METHODS

On postnatal day (PD) 4, Sprague-Dawley rat pups were assigned to five groups, GC (no alcohol [ALC], no nicotine [NIC]), ALC (4 g/kg/day), NIC (6 mg/kg/day), ALC/NIC (ALC and NIC given concurrently), or ALC-NIC (NIC administered 6 hr after ALC exposure). These rat pups were reared in an artificial-rearing apparatus from PDs 4 to 9, and the cerebellar tissues were obtained on PD 10. The total number of cerebellar Purkinje cells in the vermis was estimated using stereological methods.

RESULTS

The results showed that alcohol significantly reduced Purkinje cell numbers. The coexposure of alcohol and nicotine did not lead to further reduction in Purkinje cell number regardless of administration method, concurrent or sequential. However, alcohol and nicotine administered concurrently but not sequentially significantly lowered the BAC.

CONCLUSION

These findings suggest that the lack of increased Purkinje cell loss after the coexposure of alcohol and nicotine is independent of nicotine's ability to lower the BAC. An alternative hypothesis might be that alcohol and nicotine target the same subpopulation of Purkinje cells; therefore, no additional Purkinje cells were lost from the coexposure of these two drugs.

The effects of ethanol on the developing cerebellum and eyeblink classical conditioning

In rats, developmental ethanol exposure has been used to model the central nervous system deficits associated with human fetal alcohol syndrome. Binge-like ethanol exposure of neonatal rats depletes cells in the cerebellum, including Purkinje cells, granule cells, and deep nuclear cells, and produces deficits in simple tests of motor coordination. However, the extent to which anatomical damage is related to behavioral deficits has been difficult to estimate. Eyeblink classical conditioning is known to engage a discrete brain stem-cerebellar circuit, making it an ideal test of cerebellar functional integrity after developmental ethanol exposure. Eyeblink conditioning is a simple form of motor learning in which a neutral stimulus (such as a tone) comes to elicit an eyeblink when repeatedly paired with a stimulus that evokes an eyeblink prior to training (such as mild periorbital stimulation). In eyeblink conditioning, one of the deep cerebellar nuclei, the interpositus nucleus, as well as specific Purkinje cell populations, are sites of convergence for tone conditioned stimulus and somatosensory unconditioned stimulus information, and, together with brain stem nuclei, provide the necessary and sufficient substrate for the learned response. A series of studies have shown that eyeblink conditioning is impaired in both weanling and adult rats given binge-like exposure to ethanol as neonates. In addition, interpositus nucleus neurons from ethanol-exposed rats showed impaired activation during eyeblink conditioning. These deficits are accompanied by a permanent reduction In the deep cerebellar nuclear cell population. Because particular cerebellar cell populations are utilized in well-defined ways during eyeblink conditioning, conclusions regarding the underlying neural substrates of behavioral change after developmental ethanol exposure are greatly strengthened.

A pilot community intervention for young women with fetal alcohol spectrum disorders

Fetal Alcohol Syndrome, a permanent birth defect caused by maternal alcohol use during pregnancy, is a leading preventable cause of mental retardation. Neuropsychological deficits have been well documented, however interventions developed have not been evaluated. We describe a successful 12-month community pilot intervention with 19 young women with Fetal Alcohol Spectrum Disorders (FASD). Improved outcomes (including decreased alcohol and drug use, increased use of contraceptives and medical and mental health care services, and stable housing) were obtained by implementing a community intervention model of targeted education and collaboration with key service providers, and by using paraprofessional advocate case managers as facilitators.

Binge ethanol exposure delays development of GABAergic miniature postsynaptic currents in septal neurons

Whole cell GABA(A)R currents of septal neurons isolated from rat pups increase rapidly during the first weeks of life when inhibitory synapses are forming. Early postnatal binge ethanol intubation on days 4-9 delays this maturational up-regulation in septal neurons isolated several days later suggesting inhibitory synapse formation could be disrupted [S.-H. Hsiao, J.L. Acevedo, D.W. DuBois, K.R. Smith, J.R. West, G.D. Frye, Early postnatal ethanol intubation blunts GABA(A) receptor upregulation and modifies 3alpha-hydroxy-5alpha-pregnan-20-one sensitivity in rat MS/DB neurons, Brain Res. Dev. Brain Res. 130 (2001) 25-40]. Surprisingly, whole cell GABA(A)R function does not increase rapidly when septal neurons are grown for the same period in vitro and is not blunted by comparable ethanol exposure of the cultures [S.-H. Hsiao, D.W. DuBois, R.C. Miranda, G.D. Frye, Critically timed ethanol exposure reduces GABA(A)R function on septal neurons developing in vivo but not in vitro, Brain Res Dev. Brain Res. 1008 (2004) 69-80]. Because GABAergic miniature postsynaptic currents (mPSCs) show parallel patterns of maturation whether cortical neurons are growing in vivo or in vitro [D.D. Dunning, C.L. Hoover, I. Soltesz, M.A. Smith, D.K. ODowd, GABA(A) receptor-mediated miniature postsynaptic currents and alpha-subunit expression in developing cortical neurons, J. Neurophysiol. 82 (1999) 3286-3297], we examined the impact of binge ethanol exposure on synaptic receptors activated by these currents in septal cultures. Binge ethanol treatment of embryonic septal neurons over 6-11 days in vitro (DIV) slightly reduced GABA(A)R-mediated mPSC amplitude and frequency, but also substantially slowed decay kinetics when mPSCs were recorded later on DIV 13-18. Decreased frequency and slowed mPSC decay kinetics after ethanol were consistent with parameters measured in immature neurons. Untreated septal neurons exhibited decreased mPSC amplitude and frequency with acute 30-100 mM ethanol, without changing decay kinetics suggesting a direct inhibition of postsynaptic receptors. Sustained inhibition of GABA(A)Rs with 100 microM picrotoxin on DIV 6-11 decreased mPSC amplitude and frequency and slowed decay kinetics similar to binge ethanol exposure. These results suggest that binge ethanol exposure delays mPSC maturation by interfering with trophic postsynaptic GABA(A)R signaling during the early development of septal neurons.

Risk factors for adverse life outcomes in fetal alcohol syndrome and fetal alcohol effects

Clinical descriptions of patients with Fetal Alcohol Syndrome (FAS) and Fetal Alcohol Effects (FAE) suggest major problems with adaptive behavior. Five operationally defined adverse outcomes and 18 associated risk/protective factors were examined using a Life History Interview with knowledgeable informants of 415 patients with FAS or FAE (median age 14 years, range 6-51; median IQ 86, range 29-126). Eighty percent of these patients were not raised by their biological mothers. For adolescents and adults, the life span prevalence was 61% for Disrupted School Experiences, 60% for Trouble with the Law, 50% for Confinement (in detention, jail, prison, or a psychiatric or alcohol/drug inpatient setting), 49% for Inappropriate Sexual Behaviors on repeated occasions, and 35% for Alcohol/Drug Problems. The odds of escaping these adverse life outcomes are increased 2- to 4-fold by receiving the diagnosis of FAS or FAE at an earlier age and by being reared in good stable environments.

Bimanual coordination in alcohol-exposed children: role of the corpus callosum

The corpus callosum (CC) is one of several brain structures affected in children prenatally exposed to alcohol. This structure plays a major role in coordinating motor activity from opposite sides of the body, and deficits in bimanual coordination have been documented in individuals with agenesis of or damage to the CC, particularly when the task is performed without visual feedback. The Bimanual Coordination Test was used to assess speed and accuracy on a task where both hands must coordinate to guide a cursor through angled pathways providing measures of interhemispheric interaction or the ability of the two hemispheres to coordinate activity via the corpus callosum. Twenty-one children with fetal alcohol spectrum disorders (FASD) and 17 non-exposed control children (CON), matched closely in age, sex, and ethnicity were tested. For trials with visual feedback (WV), children with FASD were slower than CON children but were equally accurate. Although statistically significant group differences were not observed on most trials completed without visual feedback (WOV), accuracy of the FASD group on WOV trials was highly variable. Group differences in accuracy on WOV angles approached significance after accounting for performance on the WV angles, and children with FASD were significantly less accurate on an individual angle believed to be particularly sensitive to interhemispheric interaction. These results indicate that children with FASD are slower than CON children but equally accurate on basic visuomotor tasks. However, as task complexity and reliance on interhemispheric interaction increases, children with FASD demonstrate variable and inaccurate performance.

Executive functioning in preschool-age children prenatally exposed to alcohol, cocaine, and marijuana

BACKGROUND

Reports from clinical and experimental (animal) research converge on the suggestion that prenatal exposure to alcohol, cocaine, or marijuana undermines executive functioning (EF) and its neurological underpinnings. However, large, adequately controlled, prospective studies of alcohol and marijuana effects on EF have reported conflicting findings, and there have been no such studies of cocaine exposure.

METHODS

EF was investigated in a cohort (n = 316) of 4-year-old children the majority of whose mothers had used varying combinations of cocaine, alcohol, and marijuana during pregnancy. With use of postpartum maternal report and biological assay, children were assigned to overlapping prenatal cocaine-exposed, alcohol-exposed, and marijuana-exposed groups and to complementary control groups. The postnatal environmental assessment included measures of maternal intellectual and psychosocial functioning, current drug or alcohol use, and home environment.

RESULTS

The children in the alcohol-exposed group had worse tapping-inhibition performance than children in the non-alcohol-exposed group, and this effect persisted when potential confounding environmental variables, other drug variables, and concurrent verbal intelligence were controlled for.

CONCLUSIONS

Prenatal alcohol is predictive of decreased EF in early childhood that could not be attributed to environmental factors. The results are discussed in terms of the age and overall high-risk status of the children.

Differential vulnerability to motor deficits in second replicate HAS and LAS rats following neonatal alcohol exposure

Children exposed prenatally to alcohol suffer from a variety of behavioral alterations. However, variation exists in the pattern and severity of these alcohol-related neurodevelopmental disorders. We examined the influence of alcohol sensitivity in the etiology of fetal alcohol effects by studying rat lines selectively bred for extremes in alcohol-induced sleep time: high-alcohol-sensitive (HAS) and low-alcohol-sensitive (LAS) rats. Using subjects from the first replicate, we previously reported that HAS rats exposed to alcohol during development were more vulnerable to ethanol-induced hyperactivity and motor deficits compared to LAS rats. To determine if these effects were, in fact, related to the trait for which these subjects were selected, the present study examined the consequences of developmental alcohol exposure in second replicate HAS and LAS rats. Second replicate HAS and LAS rats, as well as Sprague-Dawley rats, were exposed to 6.0 g/kg/day ethanol on Postnatal Days (PD) 4-9, a period of brain development equivalent to the third trimester, via an artificial rearing procedure. Artificially and normally reared controls were included. Activity was measured on PD 18-21 and parallel bar motor coordination on PD 30-32. Ethanol exposure produced hyperactivity in all genetic groups, and there were no differences among HAS and LAS rats. In contrast, consistent with findings from the first replicate, ethanol-exposed HAS rats were more impaired on the motor coordination task compared with LAS rats. These data suggest that genetically mediated responses to alcohol may relate to behavioral vulnerability to motor deficits following developmental alcohol exposure. They also provide evidence that genetic factors play a role in fetal alcohol effects and suggest that phenotypic markers may indicate individuals at high risk for some fetal alcohol effects.

Executive functioning in preschool-age children prenatally exposed to alcohol, cocaine, and marijuana

BACKGROUND

Reports from clinical and experimental (animal) research converge on the suggestion that prenatal exposure to alcohol, cocaine, or marijuana undermines executive functioning (EF) and its neurological underpinnings. However, large, adequately controlled, prospective studies of alcohol and marijuana effects on EF have reported conflicting findings, and there have been no such studies of cocaine exposure.

METHODS

EF was investigated in a cohort (n = 316) of 4-year-old children the majority of whose mothers had used varying combinations of cocaine, alcohol, and marijuana during pregnancy. With use of postpartum maternal report and biological assay, children were assigned to overlapping prenatal cocaine-exposed, alcohol-exposed, and marijuana-exposed groups and to complementary control groups. The postnatal environmental assessment included measures of maternal intellectual and psychosocial functioning, current drug or alcohol use, and home environment.

RESULTS

The children in the alcohol-exposed group had worse tapping-inhibition performance than children in the non-alcohol-exposed group, and this effect persisted when potential confounding environmental variables, other drug variables, and concurrent verbal intelligence were controlled for.

CONCLUSIONS

Prenatal alcohol is predictive of decreased EF in early childhood that could not be attributed to environmental factors. The results are discussed in terms of the age and overall high-risk status of the children.

Midline corpus callosum is a neuroanatomical focus of fetal alcohol damage

Prenatal exposure to high levels of alcohol often induces birth defects that combine morphological stigmata with neurological or neuropsychological deficits. But it has proved problematic to diagnose these syndromes in adolescents and adults, in whom the morphological signs are absent or attenuated, the behavioral deficits nonspecific, and the exposure history often difficult to reconstruct. Localizing the associated brain abnormalities might circumvent most of these difficulties. To this end, three-dimensional (3D) locations were recorded for 67 homologous points on or near the corpus callosum in magnetic resonance (MR) brain images from 60 adolescents and adults who were normal, 60 diagnosed with fetal alcohol syndrome, and 60 diagnosed with fetal alcohol effects. We combined the standard statistical approach to this type of geometric data, Procrustes analysis, with a multivariate strategy focusing on differences in variability. In this data set, the shape of the corpus callosum and its vicinity proves systematically much more variable in the alcohol-affected brains than in those of the normal subjects. From this excess variability follows a promising classification rule, having both high sensitivity (100 out of 117) and high specificity (49 out of 60) in this sample. The discrimination uses four landmark points and two summary scores of callosal outline shape. The information from the corpus callosum and vicinity, as viewed in MR brain images of full-grown subjects, may serve as a permanent record of the prenatal effects of alcohol, even in patients who are first suspected of these syndromes relatively late in life or who lack the facial signs of prenatal alcohol damage. The statistical pattern underlying the callosal diagnosis also leads to speculations on mechanisms of the prenatal damage.

Mapping genetic influences on human brain structure

Recent advances in brain imaging and genetics have empowered the mapping of genetic and environmental influences on the human brain. These techniques shed light on the 'nature/nurture' debate, revealing how genes determine individual differences in intelligence quotient (IQ) or risk for disease. They visualize which aspects of brain structure and function are heritable, and to what degree, linking these features with behavioral or cognitive traits or disease phenotypes. In genetically transmitted disorders such as schizophrenia, patterns of brain structure can be associated with increased disease liability, and sites can be mapped where non-genetic triggers may initiate disease. We recently developed a large-scale computational brain atlas, including data components from the Finnish Twin registry, to store information on individual variations in brain structure and their heritability. Algorithms from random field theory, anatomical modeling, and population genetics were combined to detect a genetic continuum in which brain structure is heavily genetically determined in some areas but not others. These algorithmic advances motivate studies of disease in which the normative atlas acts as a quantitative reference for the heritability of structural differences and deficits in patient populations. The resulting genetic brain maps isolate biological markers for inherited traits and disease susceptibility, which may serve as targets for genetic linkage and association studies. Computational methods from brain imaging and genetics can be fruitfully merged, to shed light on the inheritance of personality differences and behavioral traits, and the genetic transmission of diseases that affect the human brain.