Human amygdala functional network development: A cross-sectional study from 3 months to 5 years of age

Although the amygdala's role in shaping social behavior is especially important during early post-natal development, very little is known of amygdala functional development before childhood. To address this gap, this study uses resting-state fMRI to examine early amygdalar functional network development in a cross-sectional sample of 80 children from 3-months to 5-years of age. Whole brain functional connectivity with the amygdala, and its laterobasal and superficial sub-regions, were largely similar to those seen in older children and adults. Functional distinctions between sub-region networks were already established. These patterns suggest many amygdala functional circuits are intact from infancy, especially those that are part of motor, visual, auditory and subcortical networks. Developmental changes in connectivity were observed between the laterobasal nucleus and bilateral ventral temporal and motor cortex as well as between the superficial nuclei and medial thalamus, occipital cortex and a different region of motor cortex. These results show amygdala-subcortical and sensory-cortex connectivity begins refinement prior to childhood, though connectivity changes with associative and frontal cortical areas, seen after early childhood, were not evident in this age range. These findings represent early steps in understanding amygdala network dynamics across infancy through early childhood, an important period of emotional and cognitive development.

Contribution to speech development of the right anterior putamen revealed with multivariate tensor-based morphometry

In our previous study1, we suggested that the difference between tensor-based metrics in the anterior part of the right putamen between 21 and 18 months age groups associated with speech development during this ages. Here we used a correlational analysis between verbal scores and determinant of the Jacobian matrix to confirm our hypothesis. Significant correlations in anterior part of the right putamen between verbal scores and surface metric were revealed in the 18 and 21 age groups.

Cranial thickness changes in early childhood

The neurocranium changes rapidly in early childhood to accommodate the developing brain. However, developmental disorders may cause abnormal growth of the neurocranium, the most common one being craniosynostosis, affecting about 1 in 2000 children. It is important to understand how the brain and neurocranium develop together to understand the role of the neurocranium in neurodevelopmental outcomes. However, the neurocranium is not as well studied as the human brain in early childhood, due to a lack of imaging data. CT is typically employed to investigate the cranium, but, due to ionizing radiation, may only be used for clinical cases. However, the neurocranium is also visible on magnetic resonance imaging (MRI). Here, we used a large dataset of MRI images from healthy children in the age range of 1 to 2 years old and extracted the neurocranium. A conformal geometry based analysis pipeline is implemented to determine a set of statistical atlases of the neurocranium. A growth model of the neurocranium will help us understand cranial bone and suture development with respect to the brain, which will in turn inform better treatment strategies for neurocranial disorders.

Central sulcus development in early childhood

Mapping out the development of the brain in early childhood is a critical part of understanding neurological disorders. The brain grows rapidly in early life, reaching 95% of the final volume by age 6. A normative atlas containing structural parameters that indicate development would be a powerful tool in understanding the progression of neurological diseases. Although some studies have begun exploring cortical development in pediatric imaging, sulci have not been examined extensively. Here, we study the changes in the Central Sulcus (CS), which is one of the earliest sulci to develop from the fetal stage, at early developmental age 1-3 years old using high resolution magnetic resonance images. Parameterization of the central sulcus was performed and results show us that the CS change corresponds to the development of the mouth and tongue regions.

Quantifying cortical development in typically developing toddlers and young children, 1-6 years of age

Cortical maturation, including age-related changes in thickness, volume, surface area, and folding (gyrification), play a central role in developing brain function and plasticity. Further, abnormal cortical maturation is a suspected substrate in various behavioral, intellectual, and psychiatric disorders. However, in order to characterize the altered development associated with these disorders, appreciation of the normative patterns of cortical development in neurotypical children between 1 and 6 years of age, a period of peak brain development during which many behavioral and developmental disorders emerge, is necessary. To this end, we examined measures of cortical thickness, surface area, mean curvature, and gray matter volume across 34 bilateral regions in a cohort of 140 healthy children devoid of major risk factors for abnormal development. From these data, we observed linear, logarithmic, and quadratic patterns of change with age depending on brain region. Cortical thinning, ranging from 10% to 20%, was observed throughout most of the brain, with the exception of posterior brain structures, which showed initial cortical thinning from 1 to 5 years, followed by thickening. Cortical surface area expansion ranged from 20% to 108%, and cortical curvature varied by 1–20% across the investigated age range. Right-left hemisphere asymmetry was observed across development for each of the 4 cortical measures. Our results present new insight into the normative patterns of cortical development across an important but under studied developmental window, and provide a valuable reference to which trajectories observed in neurodevelopmental disorders may be compared.

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Analysis of cortical thickness, surface area, curvature, and gray matter volume.

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Region specific trajectories of cortical maturation in infants and children.

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Analysis of significant asymmetry during early brain development.

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Differential brain development based on sex.

Putamen Development in Children 12 to 21 Months Old

We studied the developmental trajectory of the putamen in 13-21 months old children using multivariate surface tensor-based morphometry. Our results indicate surface changes between 12 and 15 months' age groups in the middle superior part the left putamen. The growth of the left putamen at earlier ages slows down after 15 months. The most important surface changes were detected in the right putamen between 18 and 21 months and were located in the anterior part of the structure. Our results demonstrate the heterochronic growth of the right and left putamen related to different functional subregions within putamen. Our results are compatible with previous studies devoted to total putamen volume changes during normal development.

YouTube as a crowd-generated water level archive

In view of the substantial costs associated with classic monitoring networks, participatory data collection methods can be deemed a promising option to obtain complementary data. An emerging trend in this field is social media mining, i.e., harvesting of pre-existing, crowd-generated data from social media. Although this approach is participatory in a broader sense, the users are mostly not aware of their participation in research. Inspired by this novel development, we demonstrate in this study that it is possible to derive a water level time series from the analysis of multiple YouTube videos. As an example, we studied the recent water level rise in Dahl Hith, a Saudi Arabian cave. To do so, we screened 16 YouTube videos of the cave for suitable reference points (e.g., cave graffiti). Then, we visually estimated the distances between these points and the water level and traced their changes over time. To bridge YouTube hiatuses, we considered own photos taken during two site visits. For the time period 2013-2014, we estimate a rise of 9.5m. The fact that this rise occurred at a somewhat constant rate of roughly 0.4m per month points towards a new and permanent water source, possibly two nearby lakes formed from treated sewage effluent. An anomaly in the rising rate is noted for autumn 2013 (1.3m per month). As this increased pace coincides with a cluster of rain events, we deem rapid groundwater recharge along preferential flow paths a likely cause. Despite the sacrifice in precision, we believe that YouTube harvesting may represent a viable option to gather historical water levels in data-scarce settings and that it could be adapted to other environments (e.g., flood extents). In certain areas, it might provide an additional tool for the monitoring toolbox, thereby possibly delivering hydrological data for water resources management.

Viral load strategy: impact on risk behaviour and serocommunication of men who have sex with men in specialized care

BACKGROUND

Incidence and prevalence of HIV are continuously high in German men, who have sex with men (MSM). Different transmission risk minimizing strategies have been observed. The viral load strategy rates patients unlikely to be sexually infectious if their viral load under effective therapy is stably suppressed during 6 months and no other sexually transmitted infections are present.

OBJECTIVES

We aim to objectify the current popularity of the viral load strategy, the adherence to basic conditions and its impact on risk behaviour and serocommunication. Until now, no data on a German sample of HIV-positive MSM in regular specialized outpatient care are available.

METHODS

Cross-sectional study with group comparisons between user group and non-user-group of the viral load strategy. Self-report questionnaires were conducted with 269 sexually active German HIV+MSM under effective treatment in specialized outpatient care. Structured interviews gathered additional information about approach to and realization of definite action levels concerning sexual risk behaviour and transmission risk minimizing strategies.

RESULTS

Twenty-seven of 269 participants (10%) affirmed knowledge of having an undetectable viral load and stated this to be criteria for unprotected sexual behaviour. This subgroup reported more unprotected insertive (P = 0.018) and receptive anal intercourse (P = 0.042), more anonymous sex partners (P = 0.008) and less consistent safer sex. Analysing serocommunication, less addressing HIV/AIDS in general (P = 0.043) and less disclosing to sex partners (P = 0.023) was found, especially in anonymous settings. Differentiating serocommunication characteristics, a focus on seroguessing was depicted.

CONCLUSIONS

The user group of the viral load strategy is small. But a less frequent, more reactive and assumptive serocommunication leads to an imprecise information exchange paired with higher frequency of risky behaviour, especially in anonymous settings, where frank serocommunication is often avoided. The targeted group of the viral load strategy diverges greatly from the user group.

Mapping an index of the myelin g-ratio in infants using magnetic resonance imaging

Optimal myelination of neuronal axons is essential for effective brain and cognitive function. The ratio of the axon diameter to the outer fiber diameter, known as the g-ratio, is a reliable measure to assess axonal myelination and is an important index reflecting the efficiency and maximal conduction velocity of white matter pathways. Although advanced neuroimaging techniques including multicomponent relaxometry (MCR) and diffusion tensor imaging afford insight into the microstructural characteristics of brain tissue, by themselves they do not allow direct analysis of the myelin g-ratio. Here, we show that by combining myelin content information (obtained with mcDESPOT MCR) with neurite density information (obtained through NODDI diffusion imaging) an index of the myelin g-ratio may be estimated. Using this framework, we present the first quantitative study of myelin g-ratio index changes across childhood, examining 18 typically developing children 3months to 7.5years of age. We report a spatio-temporal pattern of maturation that is consistent with histological and developmental MRI studies, as well as theoretical studies of the myelin g-ratio. This work represents the first ever in vivo visualization of the evolution of white matter g-ratio indices throughout early childhood.

Characterization of the central sulcus in the brain in early childhood

Characterization of the developing brain during early childhood is of interest for both neuroscience and medicine, and in particular, is key to understanding what goes wrong in neurodevelopmental disorders. In particular, the cortex grows rapidly in the first 3 years of life, and creating a normative atlas can provide a comparison tool to diagnose disorders at an early stage, thereby empowering early interventional therapies. Zooming in on specific sulci may provide additional targeted information, and notably, an understanding of central sulcus growth can provide important insight on the development of laterality. However, there currently do not exist any atlases of specific changes in sulci as the brain grows. In this pilot study, we explore regional differences in the depth of the central sulcus between two and three year old infants using brain magnetic resonance images.

Examining the relationships between cortical maturation and white matter myelination throughout early childhood

Cortical development and white matter myelination are hallmark processes of infant and child neurodevelopment, and play a central role in the evolution of cognitive and behavioral functioning. Non-invasive magnetic resonance imaging (MRI) has been used to independently track these microstructural and morphological changes in vivo, however few studies have investigated the relationship between them despite their concurrency in the developing brain. Further, because measures of cortical morphology rely on underlying gray–white matter tissue contrast, which itself is a function of white matter myelination, it is unclear if contrast-based measures of cortical development accurately reflect cortical architecture, or if they merely represent adjacent white matter maturation. This may be particularly true in young children, in whom brain structure is rapidly maturing. Here for the first time, we investigate the dynamic relationship between cortical and white matter development across early childhood, from 1 to 6 years. We present measurements of cortical thickness with respect to cortical and adjacent myelin water fraction (MWF) in 33 bilateral cortical regions. Significant results in only 14 of 66 (21%) cortical regions suggest that cortical thickness measures are not heavily driven by changes in adjacent white matter, and that brain imaging studies of cortical and white matter maturation reflect distinct, but complimentary, neurodevelopmental processes.

Cortical maturation and myelination in healthy toddlers and young children

The maturation of cortical structures, and the establishment of their connectivity, are critical neurodevelopmental processes that support and enable cognitive and behavioral functioning. Measures of cortical development, including thickness, curvature, and gyrification have been extensively studied in older children, adolescents, and adults, revealing regional associations with cognitive performance, and alterations with disease or pathology. In addition to these gross morphometric measures, increased attention has recently focused on quantifying more specific indices of cortical structure, in particular intracortical myelination, and their relationship to cognitive skills, including IQ, executive functioning, and language performance. Here we analyze the progression of cortical myelination across early childhood, from 1 to 6 years of age, in vivo for the first time. Using two quantitative imaging techniques, namely T1 relaxation time and myelin water fraction (MWF) imaging, we characterize myelination throughout the cortex, examine developmental trends, and investigate hemispheric and gender-based differences. We present a pattern of cortical myelination that broadly mirrors established histological timelines, with somatosensory, motor and visual cortices myelinating by 1 year of age; and frontal and temporal cortices exhibiting more protracted myelination. Developmental trajectories, defined by logarithmic functions (increasing for MWF, decreasing for T1), were characterized for each of 68 cortical regions. Comparisons of trajectories between hemispheres and gender revealed no significant differences. Results illustrate the ability to quantitatively map cortical myelination throughout early neurodevelopment, and may provide an important new tool for investigating typical and atypical development.

Estimating the age of healthy infants from quantitative myelin water fraction maps

The trajectory of the developing brain is characterized by a sequence of complex, nonlinear patterns that occur at systematic stages of maturation. Although significant prior neuroimaging research has shed light on these patterns, the challenge of accurately characterizing brain maturation, and identifying areas of accelerated or delayed development, remains. Altered brain development, particularly during the earliest stages of life, is believed to be associated with many neurological and neuropsychiatric disorders. In this work, we develop a framework to construct voxel-wise estimates of brain age based on magnetic resonance imaging measures sensitive to myelin content. 198 myelin water fraction (VF(M) ) maps were acquired from healthy male and female infants and toddlers, 3 to 48 months of age, and used to train a sigmoidal-based maturational model. The validity of the approach was then established by testing the model on 129 different VF(M) datasets. Results revealed the approach to have high accuracy, with a mean absolute percent error of 13% in males and 14% in females, and high predictive ability, with correlation coefficients between estimated and true ages of 0.945 in males and 0.94 in females. This work represents a new approach toward mapping brain maturity, and may provide a more faithful staging of brain maturation in infants beyond chronological or gestation-corrected age, allowing earlier identification of atypical regional brain development.

White matter maturation profiles through early childhood predict general cognitive ability

Infancy and early childhood are periods of rapid brain development, during which brain structure and function mature alongside evolving cognitive ability. An important neurodevelopmental process during this postnatal period is the maturation of the myelinated white matter, which facilitates rapid communication across neural systems and networks. Though prior brain imaging studies in children (4 years of age and above), adolescents, and adults have consistently linked white matter development with cognitive maturation and intelligence, few studies have examined how these processes are related throughout early development (birth to 4 years of age). Here, we show that the profile of white matter myelination across the first 5 years of life is strongly and specifically related to cognitive ability. Using a longitudinal design, coupled with advanced magnetic resonance imaging, we demonstrate that children with above-average ability show differential trajectories of myelin development compared to average and below average ability children, even when controlling for socioeconomic status, gestation, and birth weight. Specifically, higher ability children exhibit slower but more prolonged early development, resulting in overall increased myelin measures by ~3 years of age. These results provide new insight into the early neuroanatomical correlates of cognitive ability, and suggest an early period of prolonged maturation with associated protracted white matter plasticity may result in strengthened neural networks that can better support later development. Further, these results reinforce the necessity of a longitudinal perspective in investigating typical or suspected atypical cognitive maturation.

Nutritional influences on early white matter development: response to Anderson and Burggren

Does breastfeeding alter early brain development? In a recent retrospective study, our group examined the cross-sectional relationship between early infant feeding practice and white matter maturation and cognitive development. In groups matched for child and mother age, gestation duration, birth weight, gender distribution, and socio-economic status; we observed that children who were breastfed exclusively for at least 3 months showed, on average, increased white matter myelin development compared to children who either were exclusively formula-fed, or received a mixture of breast milk and formula. In secondary analysis on sub-sets of these children, again matched for important confounding variables, we found improved cognitive test scores of receptive language in the exclusively breast-fed children compared to formula or formula+breast-fed children; and that prolonged breastfeeding was associated with increased motor, language, and visual functioning in exclusively breast-fed children. In response to this work, Anderson and Burggren have questioned our methodology and, by association, our findings. Further, they use their critique as a platform for advancing an alternative interpretation of our findings: that observed results were not associated with prolonged breast-feeding, but rather delayed the introduction of cow's milk. In this response, we address and clarify some of the misconceptions presented by Anderson and Burggren.

Characterizing longitudinal white matter development during early childhood

Post-mortem studies have shown the maturation of the brain’s myelinated white matter, crucial for efficient and coordinated brain communication, follows a nonlinear spatio-temporal pattern that corresponds with the onset and refinement of cognitive functions and behaviors. Unfortunately, investigation of myelination in vivo is challenging and, thus, little is known about the normative pattern of myelination, or its association with functional development. Using a novel quantitative magnetic resonance imaging technique sensitive to myelin we examined longitudinal white matter development in 108 typically developing children ranging in age from 2.5 months to 5.5 years. Using nonlinear mixed effects modeling, we provide the first in vivo longitudinal description of myelin water fraction development. Moreover, we show distinct male and female developmental patterns, and demonstrate significant relationships between myelin content and measures of cognitive function. These findings advance a new understanding of healthy brain development and provide a foundation from which to assess atypical development.

Brain differences in infants at differential genetic risk for late-onset Alzheimer disease: a cross-sectional imaging study

IMPORTANCE

Converging evidence suggests brain structure alterations may precede overt cognitive impairment in Alzheimer disease by several decades. Early detection of these alterations holds inherent value for the development and evaluation of preventive treatment therapies.

OBJECTIVE

To compare magnetic resonance imaging measurements of white matter myelin water fraction (MWF) and gray matter volume (GMV) in healthy infant carriers and noncarriers of the apolipoprotein E (APOE) ε4 allele, the major susceptibility gene for late-onset AD.

DESIGN, SETTING, AND PARTICIPANTS

Quiet magnetic resonance imaging was performed at an academic research imaging center on 162 healthy, typically developing 2- to 25-month-old infants with no family history of Alzheimer disease or other neurological or psychiatric disorders. Cross-sectional measurements were compared in the APOE ε4 carrier and noncarrier groups. White matter MWF was compared in one hundred sixty-two 2- to 25-month-old sleeping infants (60 ε4 carriers and 102 noncarriers). Gray matter volume was compared in a subset of fifty-nine 6- to 25-month-old infants (23 ε4 carriers and 36 noncarriers), who remained asleep during the scanning session. The carrier and noncarrier groups were matched for age, gestational duration, birth weight, sex ratio, maternal age, education, and socioeconomic status.

MAIN OUTCOMES AND MEASURES

Automated algorithms compared regional white matter MWF and GMV in the carrier and noncarrier groups and characterized their associations with age.

RESULTS

Infant ε4 carriers had lower MWF and GMV measurements than noncarriers in precuneus, posterior/middle cingulate, lateral temporal, and medial occipitotemporal regions, areas preferentially affected by AD, and greater MWF and GMV measurements in extensive frontal regions and measurements were also significant in the subset of 2- to 6-month-old infants (MWF differences, P < .05, after correction for multiple comparisons; GMV differences, P < .001, uncorrected for multiple comparisons). Infant ε4 carriers also exhibited an attenuated relationship between MWF and age in posterior white matter regions.

CONCLUSIONS AND RELEVANCE

While our findings should be considered preliminary, this study demonstrates some of the earliest brain changes associated with the genetic predisposition to AD. It raises new questions about the role of APOE in normal human brain development, the extent to which these processes are related to subsequent AD pathology, and whether they could be targeted by AD prevention therapies.

White matter development and early cognition in babies and toddlers

The normal myelination of neuronal axons is essential to neurodevelopment, allowing fast inter-neuronal communication. The most dynamic period of myelination occurs in the first few years of life, in concert with a dramatic increase in cognitive abilities. How these processes relate, however, is still unclear. Here we aimed to use a data-driven technique to parcellate developing white matter into regions with consistent white matter growth trajectories and investigate how these regions related to cognitive development. In a large sample of 183 children aged 3 months to 4 years, we calculated whole brain myelin volume fraction (VFM ) maps using quantitative multicomponent relaxometry. We used spatial independent component analysis (ICA) to blindly segment these quantitative VFM images into anatomically meaningful parcels with distinct developmental trajectories. We further investigated the relationship of these trajectories with standardized cognitive scores in the same children. The resulting components represented a mix of unilateral and bilateral white matter regions (e.g., cortico-spinal tract, genu and splenium of the corpus callosum, white matter underlying the inferior frontal gyrus) as well as structured noise (misregistration, image artifact). The trajectories of these regions were associated with individual differences in cognitive abilities. Specifically, components in white matter underlying frontal and temporal cortices showed significant relationships to expressive and receptive language abilities. Many of these relationships had a significant interaction with age, with VFM becoming more strongly associated with language skills with age. These data provide evidence for a changing coupling between developing myelin and cognitive development.

Advances in myelin imaging with potential clinical application to pediatric imaging

White matter development and myelination are critical processes in neurodevelopment. Myelinated white matter facilitates the rapid and coordinated brain messaging required for higher-order cognitive and behavioral processing. Whereas several neurological disorders such as multiple sclerosis are associated with gross white matter damage and demyelination, other disorders such as epilepsy may involve altered myelination in the efferent or afferent white matter pathways adjoining epileptic foci. Current MRI techniques including T1 weighting, T2 weighting, FLAIR, diffusion tensor imaging, and MR spectroscopy permit visualization of gross white matter abnormalities and evaluation of underlying white matter fiber architecture and integrity, but they provide only qualitative information regarding myelin content. Quantification of these myelin changes could provide new insight into disease severity and prognosis, reveal information regarding spatial location of foci or lesions and the associated affected neural systems, and create a metric to evaluate treatment efficacy. Multicomponent analysis of T1 and T2 relaxation data, or multicomponent relaxometry (MCR), is a quantitative imaging technique that is sensitive and specific to myelin content alteration. In the past, MCR has been associated with lengthy imaging times, but a new, faster MCR technique (mcDESPOT) has made quantitative analysis of myelin content more accessible for clinical research applications. The authors briefly summarize traditional white matter imaging techniques, describe MCR and mcDESPOT, and discuss current and future clinical applications of MCR, with a particular focus on pediatric epilepsy.

Pediatric neuroimaging using magnetic resonance imaging during non-sedated sleep

BACKGROUND

Etiological studies of many neurological and psychiatric disorders are increasingly turning toward longitudinal investigations of infant brain development in order to discern predisposing structural and/or functional differences prior to the onset of overt clinical symptoms. While MRI provides a noninvasive window into the developing brain, MRI of infants and toddlers is challenging due to the modality's extreme motion sensitivity and children's difficulty in remaining still during image acquisition.

OBJECTIVE

Here, we outline a broad research protocol for successful MRI of children under 4 years of age during natural, non-sedated sleep.

MATERIALS AND METHODS

All children were imaged during natural, non-sedated sleep. Active and passive measures to reduce acoustic noise were implemented to reduce the likelihood of the children waking up during acquisition. Foam cushions and vacuum immobilizers were used to limit intra-scan motion artifacts.

RESULTS

More than 380 MRI datasets have been successfully acquired from 220 children younger than 4 years of age within the past 39 months. Implemented measures permitted children to remain asleep for the duration of the scan and allowed the data to be acquired with an overall 97% success rate.

CONCLUSION

The proposed method greatly advances current pediatric imaging techniques and may be readily implemented in other research and clinical settings to facilitate and further improve pediatric neuroimaging.

Breastfeeding and early white matter development: A cross-sectional study

Does breastfeeding alter early brain development? The prevailing consensus from large epidemiological studies posits that early exclusive breastfeeding is associated with improved measures of IQ and cognitive functioning in later childhood and adolescence. Prior morphometric brain imaging studies support these findings, revealing increased white matter and sub-cortical gray matter volume, and parietal lobe cortical thickness, associated with IQ, in adolescents who were breastfed as infants compared to those who were exclusively formula-fed. Yet it remains unknown when these structural differences first manifest and when developmental differences that predict later performance improvements can be detected. In this study, we used quiet magnetic resonance imaging (MRI) scans to compare measures of white matter microstructure (mcDESPOT measures of myelin water fraction) in 133 healthy children from 10 months through 4 years of age, who were either exclusively breastfed a minimum of 3 months; exclusively formula-fed; or received a mixture of breast milk and formula. We also examined the relationship between breastfeeding duration and white matter microstructure. Breastfed children exhibited increased white matter development in later maturing frontal and association brain regions. Positive relationships between white matter microstructure and breastfeeding duration are also exhibited in several brain regions, that are anatomically consistent with observed improvements in cognitive and behavioral performance measures. While the mechanisms underlying these structural differences remains unclear, our findings provide new insight into the earliest developmental advantages associated with breastfeeding, and support the hypothesis that breast milk constituents promote healthy neural growth and white matter development.

Modeling healthy male white matter and myelin development: 3 through 60months of age

An emerging hypothesis in developmental and behavioral disorders is that they arise from disorganized brain messaging or reduced connectivity. Given the importance of myelin to efficient brain communication, characterization of myelin development in infancy and childhood may provide salient information related to early connectivity deficits. In this work, we investigate regional and whole brain growth trajectories of the myelin water fraction, a quantitative magnetic resonance imaging measure sensitive and specific to myelin content, in data acquired from 122 healthy male children from 3 to 60 months of age. We examine common growth functions to find the most representative model of myelin maturation and subsequently use the best of these models to develop a continuous population-averaged, four-dimensional model of normative myelination. Through comparisons with an independent sample of 63 male children across the same age span, we show that the developed model is representative of this population. This work contributes to understanding the trajectory of myelination in healthy infants and toddlers, furthering our knowledge of early brain development, and provides a model that may be useful for identifying developmental abnormalities.

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Proposes various growth models for modeling MWF trajectories

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Demonstrates modeling of MWF trajectories of 122 male infants under 5 years

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Statistically compares tested models using Bayesian information criterion

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Generates first four-dimensional model of whole-brain myelination of early childhood

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Discusses the utility of developed model

Investigating white matter development in infancy and early childhood using myelin water faction and relaxation time mapping

The elaboration of the myelinated white matter is essential for normal neurodevelopment, establishing and mediating rapid communication pathways throughout the brain. These pathways facilitate the synchronized communication required for higher order behavioral and cognitive functioning. Altered neural messaging (or ‘disconnectivity’) arising from abnormal white matter and myelin development may underlie a number of neurodevelopmental psychiatric disorders. Despite the vital role myelin plays, few imaging studies have specifically examined its maturation throughout early infancy and childhood. Thus, direct investigations of the relationship(s) between evolving behavioral and cognitive functions and the myelination of the supporting neural systems have been sparse. Further, without knowledge of the ‘normative’ developmental time-course, identification of early abnormalities associated with developmental disorders remains challenging. In this work, we examined the use of longitudinal (T₁) and transverse (T₂) relaxation time mapping, and myelin water fraction (MWF) imaging to investigate white matter and myelin development in 153 healthy male and female children, 3 months through 60 months in age. Optimized age-specific acquisition protocols were developed using the DESPOT and mcDESPOT imaging techniques; and mean T₁, T₂ and MWF trajectories were determined for frontal, temporal, occipital, parietal and cerebellar white matter, and genu, body and splenium of the corpus callosum. MWF results provided a spatio-temporal pattern in-line with prior histological studies of myelination. Comparison of T₁, T₂ and MWF measurements demonstrates dissimilar sensitivity to tissue changes associated with neurodevelopment, with each providing differential but complementary information.

Substance use and sexual risk behaviour among HIV-positive men who have sex with men in specialized out-patient clinics

OBJECTIVES

Unprotected sexual intercourse between men who have sex with men (MSM) is the most common route of HIV infection in Germany. Approximately 70% of newly infected people are MSM. Substance use is a determinant of sexual risk behaviour in the general population, but also in the MSM subpopulation. There are only a few studies, from the USA, on the correlation between substance use and sexual risk behaviour in HIV-infected MSM in specialized care.

METHODS

In a German sample of 445 HIV-infected MSM treated in specialized out-patient clinics, the influence of substance use on sexual risk behaviour was investigated. Information was obtained from subjects using self-report questionnaires and a structured interview.

RESULTS

Recreational drug use was common. The prevalences of cannabis addiction (4.5%), harmful use of cannabis (4.3%) and harmful use of dissociative anaesthetics (0.4%) were higher than in the general German male population. A substantial proportion of patients reported unprotected insertive (32.9%) and receptive (34.6%) anal intercourse during the last 12 months. Use of cannabis, amyl nitrite, dissociative anaesthetics, cocaine, amphetamines and erectile dysfunction medication was significantly correlated with unprotected sexual contacts. Substance use in the context of sexual activity significantly increased sexual risk behaviour.

CONCLUSIONS

Substance use, especially in the context of sexual activity, should be taken into account when developing new prevention and intervention programmes aimed at reducing sexual risk behaviour in HIV-infected MSM currently in specialized care.

Localization of phosphoserine residues in the alpha subunit of rabbit skeletal muscle phosphorylase kinase

The alpha subunit of skeletal muscle phosphorylase kinase, as isolated, carries phosphate at the serine residues 1018, 1020 and 1023. Employing the S-ethyl-cysteine method, these residues are found to be phosphorylated partially, i.e. differently phosphorylated species exist in muscle. Serine 1018 is a site which can be phosphorylated by the cyclic-AMP-dependent protein kinase. The serine residues 972, 985 and 1007 are phosphorylated by phosphorylase kinase itself when its activity is stimulated by micromolar concentrations of Ca2+. These phosphorylation sites are not identical to those found to be phosphorylated already in the enzyme as prepared from freshly excised muscle. A 'multiphosphorylation loop' uniquely present in this but not in the homologous beta subunit contains all the phosphoserine residues so far identified in the alpha subunit.

[Diagnostic problems of hyperthyroidism in the older age group (author's transl)]

Seventy-seven patients aged more than 60 years from the iodine deficiency area of southern Lower Saxony with hyperthyroidism, diagnosed by assessment of thyroid parameters, showed a nonspecific disease picture with surprising frequency when compared with younger patients. Predominant characteristics were weight loss (86%), general weakness (78%), tachycardia (74%), reduced appetite (66%), exertional dyspnoea (60%), apathy, lack of initiative or depression (48%), and uncharacteristic abdominal complaints (20%). A goitre was not palpable in 30 patients (39%). Laboratory diagnosis was hampered by relative or absolute TBG deficiency and conversion inhibition in the form of a low-T3 syndrome as evidence of non-thyroidal changes in generalised disorders. Neither thyroxine nor triiodothyronine were increased in ten patients (13%). Only by additional routine estimation of the thyroxine-binding index (T3 in vitro test) as indicator of free binding capacity could the diagnosis be ascertained in these cases. The poor prognosis be ascertained in these cases. The poor prognosis of hyperthyroidism in the older age group necessitates generous use of specific diagnostic laboratory investigations in cases with suspicious symptoms.

Metabolic and clinical studies on patients with acromegaly treated with bromocriptine over 22 months

In twenty-two patients with active acromegaly who were untreated or unsuccessfully operated or irradiated (mean growth hormone (GH) values greater than 4 ng/ml) the following investigations were performed: routine laboratory tests, tomography of pituitary fossa, oral glucose tolerance tests, TRH and other pituitary function tests and GH profiles over 5-10 h before and during bromocriptine treatment with daily doses between 7.5 and 50 mg. In seventeen patients GH was suppressed to less than 50% by bromocriptine, in thirteen of them it was normalized on at least one occasion. A TRH induced GH release was observed in all but two responders to bromocriptine before therapy. This effect of TRH was not blunted during treatment with bromocriptine and also in the two patients with negative tests before therapy a significant GH increase was observed. In no non-responder to bromocriptine was a significant increase of GH after TRH observed. One patient showed a secondary resistance to bromocriptine during a period of treatment with griseofulvin. In the remaining sixteen patients the GH suppression has been consistent for between 3 and 22 months. A single dose of pimozide abolished the bromocriptine effect on GH totally in one patient; in others a slight or no significant effect was observed. Tissue swelling and sweating decreased in all bromocriptine responders and glucose tolerance improved in five patients. In four diabetic patients a partial or full remission of diabetes occurred. Apart from postural hypotension after the first administration in two patients no other severe side effects have been observed. Sella size and the other pituitary functions did not change during the time of the study. It seems that a high percentage of acromegalics may be successfully treated with bromocriptine.

[Therapy of acromegaly using bromocriptine]

Oral administration of 1.0 or 2.5 mg bromocriptine (CB 154: 2-brom-alpha-ergocryptine) in nine of twelve patients with active acromegaly resulted in a reduction of growth hormone level by 80-90% over 8-10 hours. During treatment for 2-9 months with daily doses of 4.0 to 10.0 mg bromocriptine, there was a sustained reduction of growth hormone levels in these patients. At the same time soft-tissue swellings and tendency towards sweating decreased. In two patients with diabetes mellitus the blood sugar profile improved and in one of them the insulin dose could be markedly reduced. The rise in growth hormone levels after TRH administration also occurred during bromocriptine treatment. In those patients in whom growth hormone levels failed to react to either acute or chronic administration of bromocriptine no rise followed TRH administration. It is possible that in these patients there is a hypophyseal adenoma without hypothalamic control. On gradually increasing dosage bromocriptine was tolerated without side effects.