From Alpha Diversity to Zzz: Interactions among sleep, the brain, and gut microbiota in the first year of life

Sleep disorders have been linked to alterations of gut microbiota composition in adult humans and animal models, but it is unclear how this link develops. With longitudinal assessments in 162 healthy infants, we present a so far unrecognized sleep-brain-gut interrelationship. First, we report a link between sleep habits and gut microbiota: daytime sleep is associated with bacterial diversity, and nighttime sleep fragmentation and variability link with bacterial maturity and enterotype. Second, we demonstrate a sleep-brain-gut link: bacterial diversity and enterotype are associated with sleep neurophysiology. Third, we show that the sleep-brain-gut link is relevant in development: sleep habits and bacterial markers predict behavioral-developmental outcomes. Our results demonstrate the dynamic interplay between sleep, gut microbiota, and the maturation of brain and behavior during infancy, which aligns with the lately emerging concept of a sleep-brain-gut axis. Importantly, sleep and gut microbiota represent promising health targets since both can be modified non-invasively. As many adult diseases root in early childhood, leveraging protective factors of adequate sleep and age-appropriate gut microbiota in infancy could constitute a health promoting factor across the entire human lifespan.

0321 Increased Slow-Wave Activity Predicts Slower Processing Speed in Toddlers

Introduction

Slow-wave activity (SWA) shows an inverted U-shaped time course during development. Specifically, maximal SWA undergoes a posteroanterior shift from 2 to 20 years of age, which may reflect cortical maturation. Previously, we showed that greater slow sigma power during sleep predicted faster reaction time in preschool-aged children. To date, little is known about the relationship between SWA and processing speed (PS), a basic fundament underlying complex cognitive skills in early development.

Methods

This project examined the relationship between SWA and PS in 2.5-3.0-year-old children (n=26, 50% males) via home-based assessments. After a 5-day stabilization sleep schedule, a baseline sleep EEG recording was performed on participants at 4 electrode placements: Fz, Oz, C3, and C4. SWA EEG spectral power was quantified in the 0.75-4.5 Hz rangeduring the first 60 minutes of NREM sleep. PS was obtained as part of a standard cognitive assessment via a computer-based task one hour after waking from a midday nap.

Results

On average, reaction time (PS) was 2111 ± 08 ms and SWA was 856.4 ± 300.7 µV2/Hz. Increased SWA in the occipital region was predictive of a longer reaction time and therefore slower PS (r = 0.44, p = 0.03). This relationship showed differences between sexes, suggesting that females (r = 0.26, p = 0.07) may show a stronger association between SWA in the occipital brain region and PS than males (r = 0.09, p = 0.33).

Conclusion

Interestingly, these findings contradict our hypothesis based on previous data with older children indicating that greater SWA was associated with more advanced behavioral and cognitive skills. This discrepancy may reflect the stark individual differences present within this rapidly maturing age group.

Support

Research support from NIH R01-MH086566 to MKL.

Transport through correlated systems with density functional theory

We present recent advances in density functional theory (DFT) for applications in the field of quantum transport, with particular emphasis on transport through strongly correlated systems. We review the foundations of the popular Landauer-Büttiker(LB)  +  DFT approach. This formalism, when using approximations to the exchange-correlation (xc) potential with steps at integer occupation, correctly captures the Kondo plateau in the zero bias conductance at zero temperature but completely fails to capture the transition to the Coulomb blockade (CB) regime as the temperature increases. To overcome the limitations of LB  +  DFT, the quantum transport problem is treated from a time-dependent (TD) perspective using TDDFT, an exact framework to deal with nonequilibrium situations. The steady-state limit of TDDFT shows that in addition to an xc potential in the junction, there also exists an xc correction to the applied bias. Open shell molecules in the CB regime provide the most striking examples of the importance of the xc bias correction. Using the Anderson model as guidance we estimate these corrections in the limit of zero bias. For the general case we put forward a steady-state DFT which is based on one-to-one correspondence between the pair of basic variables, steady density on and steady current across the junction and the pair local potential on and bias across the junction. Like TDDFT, this framework also leads to both an xc potential in the junction and an xc correction to the bias. Unlike TDDFT, these potentials are independent of history. We highlight the universal features of both xc potential and xc bias corrections for junctions in the CB regime and provide an accurate parametrization for the Anderson model at arbitrary temperatures and interaction strengths, thus providing a unified DFT description for both Kondo and CB regimes and the transition between them.

Steady-State Density Functional Theory for Finite Bias Conductances

In the framework of density functional theory, a formalism to describe electronic transport in the steady state is proposed which uses the density on the junction and the steady current as basic variables. We prove that, in a finite window around zero bias, there is a one-to-one map between the basic variables and both local potential on as well as bias across the junction. The resulting Kohn-Sham system features two exchange-correlation (xc) potentials, a local xc potential, and an xc contribution to the bias. For weakly coupled junctions the xc potentials exhibit steps in the density-current plane which are shown to be crucial to describe the Coulomb blockade diamonds. At small currents these steps emerge as the equilibrium xc discontinuity bifurcates. The formalism is applied to a model benzene junction, finding perfect agreement with the orthodox theory of Coulomb blockade.

The effects of caffeine on sleep and maturational markers in the rat

Adolescence is a critical period for brain maturation during which a massive reorganization of cortical connectivity takes place. In humans, slow wave activity (<4.5 Hz) during NREM sleep was proposed to reflect cortical maturation which relies on use-dependent processes. A stimulant like caffeine, whose consumption has recently increased especially in adolescents, is known to affect sleep wake regulation.

The goal of this study was to establish a rat model allowing to assess the relationship between cortical maturation and sleep and to further investigate how these parameters are affected by caffeine consumption. To do so, we assessed sleep and markers of maturation by electrophysiological recordings, behavioral and structural readouts in the juvenile rat. Our results show that sleep slow wave activity follows a similar inverted U-shape trajectory as already known in humans. Caffeine treatment exerted short-term stimulating effects and altered the trajectory of slow wave activity. Moreover, caffeine affected behavioral and structural markers of maturation. Thus, caffeine consumption during a critical developmental period shows long lasting effects on sleep and brain maturation.

Dynamical correction to linear Kohn-Sham conductances from static density functional theory

For molecules weakly coupled to leads the exact linear Kohn-Sham (KS) conductance can be orders of magnitude larger than the true linear conductance due to the lack of dynamical exchange-correlation (xc) corrections. In this work we show how to incorporate dynamical effects in KS transport calculations. The only quantity needed is the static xc potential in the molecular junction. Our scheme provides a comprehensive description of Coulomb blockade without breaking the spin symmetry. This is explicitly demonstrated in single-wall nanotubes where the corrected conductance is in good agreement with experimental data whereas the KS conductance fails dramatically.

The sleep EEG topography in children and adolescents shows sex differences in language areas

The topographic distribution of slow wave activity (SWA, EEG power between 0.75 and 4.5 Hz) during non-rapid eye movement (NREM) sleep was proposed to mirror cortical maturation with a typical age-related pattern. Here, we examined whether sex differences occur in SWA topography of children and adolescents (22 age-matched subjects, 11 boys, mean age 13.4 years, range: 8.7-19.4, and 11 girls, mean age 13.4 years, range: 9.1-19.0 years). In females, SWA during the first 60 min of NREM sleep was higher over bilateral cortical areas that are related to language functions, while in males SWA was increased over the right prefrontal cortex, a region also involved in spatial abilities. We conclude that cortical areas governing functions in which one sex outperforms the other exhibit increased sleep SWA and, thus, may indicate maturation of sex-specific brain function and higher cortical plasticity during development.

Towards a description of the Kondo effect using time-dependent density-functional theory

We demonstrate that the zero-temperature conductance of the Anderson model can be calculated within the Landauer formalism combined with static density-functional theory. The proposed approximate functional is based on finite-temperature density-functional theory and yields the exact Kohn-Sham potential at the particle-hole symmetric point. Furthermore, in the limit of zero temperature it correctly exhibits a derivative discontinuity which is shown to be essential to reproduce the conductance plateau. On the other hand, at the Kondo temperature the exact Kohn-Sham conductance overestimates the real one by an order of magnitude. To understand the failure of density-functional theory, we resort to its time-dependent version and conclude that the suppression of the Kondo resonance must be attributed to dynamical exchange-correlation corrections.

The sleep EEG as a marker of intellectual ability in school age children

STUDY OBJECTIVES

To investigate the within-subject stability in the sleep EEG and the association between the sleep EEG and intellectual abilities in 9- to 12-year-old children.

DESIGN

Intellectual ability (WISC-IV, full scale, fluid, and verbal IQ, working memory, speed of processing) were examined and all-night polysomnography was performed (2 nights per subject).

SETTING

Sleep laboratory.

PARTICIPANTS

Fourteen healthy children (mean age 10.5 ± 1.0 years; 6 girls).

MEASUREMENTS AND RESULTS

Spectral analysis was performed on artifact-free NREM sleep epochs (C3/A2). To determine intra-individual stability and inter-individual variability of the sleep EEG, power spectra were used as feature vectors for the estimation of Euclidean distances, and intraclass correlation coefficients (ICC) were calculated for the 2 nights. Sleep spindle peaks were identified for each individual and individual sigma band power was determined. Trait-like aspects of the sleep EEG were observed for sleep stage variables and spectral power. Within-subject distances were smaller than between-subject distances and ICC values ranged from 0.72 to 0.96. Correlations between spectral power in individual frequency bins and intelligence scores revealed clusters of positive associations in the alpha, sigma, and beta range for full scale IQ, fluid IQ, and working memory. Similar to adults, sigma power correlated with full scale (r = 0.67) and fluid IQ (r = 0.65), but not with verbal IQ. Spindle peak frequency was negatively related to full scale IQ (r = -0.56).

CONCLUSIONS

The sleep EEG during childhood shows high within-subject stability and may be a marker for intellectual ability.

EEG sleep slow-wave activity as a mirror of cortical maturation

Deep (slow wave) sleep shows extensive maturational changes from childhood through adolescence, which is reflected in a decrease of sleep depth measured as the activity of electroencephalographic (EEG) slow waves. This decrease in sleep depth is paralleled by massive synaptic remodeling during adolescence as observed in anatomical studies, which supports the notion that adolescence represents a sensitive period for cortical maturation. To assess the relationship between slow-wave activity (SWA) and cortical maturation, we acquired sleep EEG and magnetic resonance imaging data in children and adolescents between 8 and 19 years. We observed a tight relationship between sleep SWA and a variety of indexes of cortical maturation derived from magnetic resonance (MR) images. Specifically, gray matter volumes in regions correlating positively with the activity of slow waves largely overlapped with brain areas exhibiting an age-dependent decrease in gray matter. The positive relationship between SWA and cortical gray matter was present also for power in other frequency ranges (theta, alpha, sigma, and beta) and other vigilance states (theta during rapid eye movement sleep). Our findings indicate a strong relationship between sleep EEG activity and cortical maturation. We propose that in particular, sleep SWA represents a good marker for structural changes in neuronal networks reflecting cortical maturation during adolescence.

Dynamical Coulomb blockade and the derivative discontinuity of time-dependent density functional theory

The role of the discontinuity of the exchange-correlation potential of density functional theory is studied in the context of electron transport and shown to be intimately related to Coulomb blockade. By following the time evolution of an interacting nanojunction attached to biased leads, we find that, instead of evolving to a steady state, the system reaches a dynamical state characterized by correlation-induced current oscillations. Our results establish a dynamical picture of Coulomb blockade manifesting itself as a periodic sequence of charging and discharging of the nanostructure.

Characteristics of sleep slow waves in children and adolescents

STUDY OBJECTIVES

Slow waves, a major electrophysiological characteristic of non-rapid eye movement sleep, undergo prominent changes across puberty. This study provides a detailed description of sleep slow waves of prepubertal children and mature adolescents to better understand the mechanisms underlying the decrease of activity in the slow-wave frequency range across puberty.

DESIGN

All-night sleep electroencephalographic recordings were performed for baseline and after sleep deprivation.

SETTING

N/A.

PARTICIPANTS

Eight prepubertal children (Tanner 1/2, 11.9 +/- 0.8 years, 3 boys) and 6 mature adolescents (Tanner 4/5, 14.3 +/- 1.4 years, 3 boys).

INTERVENTIONS

Thirty-six hours of sleep deprivation.

MEASUREMENTS AND RESULTS

Both during baseline and after sleep deprivation, a steeper slope of slow waves was observed in prepubertal children (351.0 +/- 49.5 microV/s), compared with mature adolescents (215.0 +/- 27.2 microV/s, P<0.05; mean of first 5 NREM sleep episodes from baseline), even accounting for overall amplitude differences.

CONCLUSIONS

Based on a recent thalamocortical computer model, these findings may indicate a greater synaptic strength of neurons involved in the generation of sleep slow waves in prepubertal children, compared with mature adolescents. Such increased synaptic strength may be due to greater density or greater efficacy of cortical synapses or both.

Orbital currents in the Colle-Salvetti correlation energy functional and the degeneracy problem

Popular density functionals for the exchange-correlation energy typically fail to reproduce the degeneracy of different ground states of open-shell atoms. As a remedy, functionals which explicitly depend on the current density have been suggested. We present an analysis of this problem by investigating functionals that explicitly depend on the Kohn-Sham orbitals. Going beyond the exact-exchange approximation by adding correlation in the form of the Colle-Salvetti functional, we show how current-dependent terms enter the Colle-Salvetti expression and their relevance is evaluated. A very good description of the degeneracy of ground states for atoms of the first and second rows of the Periodic Table is obtained.

First-principles approach to noncollinear magnetism: towards spin dynamics

A description of noncollinear magnetism in the framework of spin-density functional theory is presented for the exact exchange energy functional which depends explicitly on two-component spinor orbitals. The equations for the effective Kohn-Sham scalar potential and magnetic field are derived within the optimized effective potential (OEP) framework. With the example of a magnetically frustrated Cr monolayer it is shown that the resulting magnetization density exhibits much more noncollinear structure than standard calculations. Furthermore, a time-dependent generalization of the noncollinear OEP method is well suited for an ab initio description of spin dynamics. We also show that the magnetic moments of solids Fe, Co, and Ni are well reproduced.

On the degeneracy of atomic states within exact-exchange (spin-) density functional theory

The problem of degenerate ground states of open-shell atoms is investigated in spin-restricted and spin-unrestricted density functional theories using the exact-exchange energy functional. For the spin-unrestricted case, spurious energy splittings of the order of 2-3 kcal/mol are found for atoms of the second and third periods which are larger than the splittings obtained from recently proposed approximate exchange functionals depending explicitly on the current density. In remarkable contrast, for spin-restricted calculations the degeneracy of different atomic ground states is recovered to within less than 0.6 kcal/mol.

Simulation of all-order density-functional perturbation theory, using the second order and the strong-correlation limit

To boost the accuracy of electronic structure calculations, the exchange-correlation energy may be constructed from the Kohn-Sham orbitals. A formally exact construction is the density-functional perturbation series, which appears to diverge for many real systems. We predict the radius of convergence and resum this series, using only exact exchange and second-order correlation plus explicit density functionals for the strong-interaction limit. Our new correlation functional, along with exact exchange, predicts atomization energies with competitive accuracy and without the usual error cancellation.

Combined schedule of 7-valent pneumococcal conjugate vaccine followed by 23-valent pneumococcal vaccine in children and young adults with sickle cell disease

We compared the immunogenicity of 7-valent pneumococcal-conjugate vaccine plus 23-valent pneumococcal vaccine to immunization with 23-valent vaccine only in individuals > or = 2 years of age with sickle cell disease. IgG pneumococcal antibody concentrations were higher in the combined schedule group with no increase in side effects observed after immunization with 23-valent vaccine.

Intraarterial hepatic chemotherapy with fluorouracil, fluorodeoxyuridine, mitomycin C, cisplatin or methotrexate as single-agent anticancer drugs for a transplanted experimental liver tumor in rats

A prospective, controlled and standardized animal experiment was performed to study the influence of various anticancer drugs. The Novikoff hepatoma transplanted into male Sprague-Dawley rats was treated with fluorouracil (FUra), mitomycin C, methotrexate, cisplatin and fluorodeoxyuridine (FdUrd) at equi-effective dosage, in terms of side effects (weight loss), in comparison to a control group (0.9% saline solution) by locoregional application via the hepatic artery. The tumor multiplication factor (TMF = tumor volume day 12/tumor volume day 5) served as the parameter to compare the tumor growth of the various groups. All drugs showed a significant (P < 0.05) effect on the tumor growth. In comparison to the control group (mean TMF 9.66), FdUrd (3.78) and FUra (3.03) only limited the tumor growth, mitomycin C (0.96) produced stable tumor, cisplatin (0.64) and methotrexate (0.15) significantly reduced (P < 0.01) the tumor size. We suggest that, in addition to the established (FUra, FdUrd, mitomycin C) drugs, methotrexate and cisplatin should be considered in further studies of the treatment of primary and secondary liver malignancies.

Therapy with oral clotrimazole induces inhibition of the Gardos channel and reduction of erythrocyte dehydration in patients with sickle cell disease

Pathologic water loss from sickle erythrocytes concentrates the abnormal hemoglobin and promotes sickling. The Ca2+-activated K+ channel (Gardos channel) contributes to this deleterious dehydration in vitro, and blockade of K+ and water loss via this channel could be a potential therapy in vivo. We treated five subjects who have sickle cell anemia with oral clotrimazole, a specific Gardos channel inhibitor. Patients were started on a dose of 10 mg clotrimazole/kg/d for one week. Protocol design allowed the daily dose to be escalated by 10 mg/kg each week until significant changes in erythrocyte density and K+ transport were achieved. Blood was sampled three times a week for hematological and chemical assays, erythrocyte density, cation content, and K+ transport. At dosages of 20 mg clotrimazole/kg/d, all subjects showed Gardos channel inhibition, reduced erythrocyte dehydration, increased cell K+ content, and somewhat increased hemoglobin levels. Adverse effects were limited to mild/moderate dysuria in all subjects, and a reversible increase in plasma alanine transaminase and aspartic transaminase levels in two subjects treated with 30 mg clotrimazole/kg/d. This is the first in vivo evidence that the Gardos channel causes dehydration of sickle erythrocytes, and that its pharmacologic inhibition provides a realistic antisickling strategy.

Quantitative volumetric analysis of brain MR: normative database spanning 5 decades of life

PURPOSE

To present a normative volumetric database, spanning 5 decades of life, of cerebrospinal fluid, subarachnoid cerebrospinal fluid, total brain volume, total ventricular volume (component ventricular volumes of lateral, temporal horn, and third and fourth ventricles) and estimates of white and gray matter, based on a multispectral segmentation of brain MR. This database is presented as a reference for future studies comparing pathologic states.

METHOD

One hundred ninety-four healthy subjects, ranging in age from 16 to 65 years, received standard axial intermediate- and T2-weighted spin-echo MR images. Multispectral segmentation and volume analysis were performed using ANALYZE.

RESULTS

Normative volumetric estimates, both uncorrected and corrected for differences in total intracranial volume, were obtained for all subjects and presented by decade and sex. Age-related cerebrospinal fluid changes were evident for both male and female subjects. Most gender differences were eliminated by correction for differences in total intracranial volume. Standard and fast spin-echo acquisition methods gave comparable volume estimates. Total brain volume measurements from MR compare favorably with data from large autopsy series.

CONCLUSION

Although there may be limitations to generalizations, these normative data tables can provide a comparison index for contrasting pathologic groups with a normative sample.

Day of injury CT scan as an index to pre-injury brain morphology

This study compared the ventricle-to-brain ratio (VBR) of the day-of-injury (DOI) computerized tomogram (CT) in traumatic brain-injured (TBI) patients with post-injury (2 months or greater) magnetic resonance (MR) VBRs in the same patients and in medical control subjects. The DOI VBR did not differ significantly from the medical controls, but both (DOI and medical control VBR) differed significantly from post-injury VBR. Additionally, a case study is presented wherein MR imaging studies were obtained prior to TBI so that a direct comparison of pre-injury to DOI to post-injury changes could be made. In this case the pre-injury and DOI VBRs were within approximately 9% of each other. In contrast, the post-injury VBR demonstrated over a 100% increase in comparison to either the pre-injury or DOI scan. This case and another case are illustrated using three-dimensional image analysis to represent ventricular change over time. These cases, along with the similarity of the DOI VBR with the medical controls, suggests that the DOI VBR can be utilized as an estimate or index of pre-injury ventricle/brain morphology. This will permit the use of DOI CT data for within-subject designs in TBI research that examines the course of degenerative changes over time.

Day-of-injury CT as an index to pre-injury brain morphology: degree of post-injury degenerative changes identified by CT and MR neuroimaging

A detailed case study is presented in which pre-injury CT scan findings are compared and contrasted with post-injury CT and MR results in a case of traumatic brain injury (TBI). The day-of-injury scan represented an adequate estimate of pre-injury morphological status based on cross-sectional area measurements of the ventricular system. By comparing pre-injury CT measurements with those obtained on the day of injury, 2 days post-injury and 16 months post-injury via assessing cross-sectional area of select ventricular regions (e.g. anterior and temporal horns, body and third ventricle) it was demonstrated that the TBI induced over a 50% ventricular expansion. Such ventricular expansions are felt to provide some index into diffuse axonal injury which may provide a means of eventually quantifying the degree of structural damage secondary to TBI. This analysis also demonstrated that there were no significant differences between selected cross-sectional ventricular areas in the 15 day and 16 month post-injury MR scans. This finding suggests that the degenerative effects of TBI have a rapid onset and are becoming readily apparent by 15 days post-injury. Thus, early imaging may provide a good index of long-term morphological outcome in TBI.