Delay of cortical thinning in very preterm born children

BACKGROUND: Cortical gray matter thinning occurs during childhood due to pruning of inefficient synaptic connections and an increase in myelination. Preterms show alterations in brain structure, with prolonged maturation of the frontal lobes, smaller cortical volumes and reduced white matter volume. These findings give rise to the question if there is a differential influence of age on cortical thinning in preterms compared to controls. AIMS: To investigate the relationship between age and cortical thinning in school-aged preterms compared to controls. STUDY DESIGN AND OUTCOME MEASURES: The automated surface reconstruction software FreeSurfer was applied to obtain measurements of cortical thickness based on T1-weighted MRI images. SUBJECTS: Forty-one preterms (<32weeks gestational age and/or <1500g birth weight) and 30 controls were included in the study (7-12years). RESULTS: In preterms, age correlated negatively with cortical thickness in right frontal, parietal and inferior temporal regions. Furthermore, young preterms showed a thicker cortex compared to old preterms in bilateral frontal, parietal and temporal regions. In controls, age was not associated with cortical thickness. CONCLUSION: In preterms, cortical thinning still seems to occur between the age of 7 and 12years, mainly in frontal and parietal areas whereas in controls, a substantial part of cortical thinning appears to be completed before they reach the age of 7years. These data indicate slower cortical thinning in preterms than in controls.

Limbic white matter microstructure plasticity reflects recovery from depression

BACKGROUND White matter microstructure alterations of limbic and reward pathways have been reported repeatedly for depressive episodes in major depressive disorder (MDD) and bipolar disorder (BD). However, findings during remission are equivocal. It was the aim of this study to investigate if white matter microstructure changes during the time course of clinical remission. METHODS Fifteen depressed patients (11 MDD, 4 BD) underwent diffusion-weighted MRI both during depression, and during remission following successful antidepressive treatment (average time interval between scans=6 months). Fractional anisotropy (FA) was sampled along reconstructions of the supero-lateral medial forebrain bundle (slMFB), the cingulum bundle (CB), the uncinate fasciculus (UF), the parahippocampal cingulum (PHC) and the fornix. Repeated measures ANCOVAs controlling for the effect of age were calculated for each tract. RESULTS There was a significant main effect of time (inter-scan interval) for mean-FA for the right CB and for the left PHC. For both pathways there was a significant time×age interaction. In the right CB, FA increased in younger patients, while FA decreased in older patients. In the left PHC, a reverse pattern was seen. FA changes in the right CB correlated positively with symptom reductions. Mean-FA of UF, slMFB and fornix did not change between the two time points. LIMITATIONS All patients were medicated, sample size, and lack of control group. CONCLUSIONS Right CB and left PHC undergo age-dependent plastic changes during the course of remission and may serve as a state marker in depression. UF, slMFB and FO microstructure remains stable.

Structural brain changes related to bilingualism: does immersion make a difference?

Abstract Within the field of neuroscientific research on second language learning, considerable attention has been devoted to functional and recently also structural changes related to second language acquisition. The present literature review summarizes studies that investigated structural changes related to bilingualism. Furthermore, as recent evidence has suggested that native-like exposure to a second language (i.e., a naturalistic learning setting or immersion) considerably impacts second language learning, all findings are reflected with respect to the learning environment. Aggregating the existing evidence, we conclude that structural changes in left inferior frontal and inferior parietal regions have been observed in studies on cortical gray matter changes, while the anterior parts of the corpus callosum have been repeatedly found to reflect bilingualism in studies on white matter (WM) connectivity. Regarding the learning environment, no cortical alterations can be attributed specifically to naturalistic or classroom learning. With regard to WM changes, one might tentatively propose that changes in IFOF and SLF are possibly more prominently observed in studies investigating bilinguals with a naturalistic learning experience. However, future studies are needed to replicate and strengthen the existing evidence and to directly test the impact of naturalistic exposure on structural brain plasticity.

Compact low-power cortical recording architecture for compressive multichannel data acquisition

This paper introduces an area- and power-efficient approach for compressive recording of cortical signals used in an implantable system prior to transmission. Recent research on compressive sensing has shown promising results for sub-Nyquist sampling of sparse biological signals. Still, any large-scale implementation of this technique faces critical issues caused by the increased hardware intensity. The cost of implementing compressive sensing in a multichannel system in terms of area usage can be significantly higher than a conventional data acquisition system without compression. To tackle this issue, a new multichannel compressive sensing scheme which exploits the spatial sparsity of the signals recorded from the electrodes of the sensor array is proposed. The analysis shows that using this method, the power efficiency is preserved to a great extent while the area overhead is significantly reduced resulting in an improved power-area product. The proposed circuit architecture is implemented in a UMC 0.18 [Formula: see text]m CMOS technology. Extensive performance analysis and design optimization has been done resulting in a low-noise, compact and power-efficient implementation. The results of simulations and subsequent reconstructions show the possibility of recovering fourfold compressed intracranial EEG signals with an SNR as high as 21.8 dB, while consuming 10.5 [Formula: see text]W of power within an effective area of 250 [Formula: see text]m × 250 [Formula: see text]m per channel.

HMG-CoA Reductase Inhibition Promotes Neurological Recovery, Peri-Lesional Tissue Remodeling, and Contralesional Pyramidal Tract Plasticity after Focal Cerebral Ischemia

3-Hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors are widely used for secondary stroke prevention. Besides their lipid-lowering activity, pleiotropic effects on neuronal survival, angiogenesis, and neurogenesis have been described. In view of these observations, we were interested whether HMG-CoA reductase inhibition in the post-acute stroke phase promotes neurological recovery, peri-lesional, and contralesional neuronal plasticity. We examined effects of the HMG-CoA reductase inhibitor rosuvastatin (0.2 or 2.0 mg/kg/day i.c.v.), administered starting 3 days after 30 min of middle cerebral artery occlusion for 30 days. Here, we show that rosuvastatin treatment significantly increased the grip strength and motor coordination of animals, promoted exploration behavior, and reduced anxiety. It was associated with structural remodeling of peri-lesional brain tissue, reflected by increased neuronal survival, enhanced capillary density, and reduced striatal and corpus callosum atrophy. Increased sprouting of contralesional pyramidal tract fibers crossing the midline in order to innervate the ipsilesional red nucleus was noticed in rosuvastatin compared with vehicle-treated mice, as shown by anterograde tract tracing experiments. Western blot analysis revealed that the abundance of HMG-CoA reductase was increased in the contralesional hemisphere at 14 and 28 days post-ischemia. Our data support the idea that HMG-CoA reductase inhibition promotes brain remodeling and plasticity far beyond the acute stroke phase, resulting in neurological recovery.

Delay of cortical thinning in very preterm born children

Objective: Cortical gray matter thinning takes place during childhood due to pruning of inefficient synaptic connections and an increase in myelination. Alterations in brain structure occur in very preterm born children with prolonged maturation of the frontal lobes and smaller cortical and white matter volume. These findings give rise to the question if age affects cortical thinning differently in very preterm born children compared to controls. The aim of the present study was to investigate the relationship between age and cortical thickness in very preterm born children when compared to controls. Participants and Methods: Forty-one very preterm born children (<32 weeks gestational age and/or < 1500 gram birth weight) and 30term born controls were included in the study (7-12 years). The automated surface reconstruction software FreeSurfer was applied to obtain measurements of cortical thickness based on T1-weighted MRI images. Results: Cortical thickness was lower in bilateral frontal and left parietal regions and higher in left temporal gyri in very preterm born children compared to controls. However, these differences depended on age. In very preterm born children, age correlated negatively with cortical thickness in right frontal, parietal and inferior temporal regions. Accordingly, cortical thickness was higher in young compared to old very preterm born children in bilateral frontal, parietal and temporal regions. In controls, age was not associated with cortical thickness. Conclusions: In very preterm born children, cortical thinning still occurs between the age of 7 and 12 years, mainly in frontal and parietal areas. In controls, however, a substantial part of cortical thinning appears to be completed in these regions before they reach the age of 7 years. These data indicate a delay in cortical thinning in very preterm born children.

Cortical thickness decreases with age in very preterm born school-children but not in term born controls

Background: Cortical gray matter thinning occurs during childhood due to pruning of inefficient synaptic connections and an increase in myelination. Preterms show alterations in brain structure, with prolonged maturation of the frontal lobes, smaller cortical volumes and reduced white matter volume. These findings give rise to the question if there is a differential influence of age on cortical thinning in preterms compared to controls. Aims: To investigate the relationship between age and cortical thickness in preterms when compared to controls. Study design and outcome measures: The automated surface reconstruction software FreeSurfer was applied to obtain measurements of cortical thickness based on T1-weighted MRI images. Subjects: Forty-one preterms (< 32 weeks gestational age and/or < 1500 gram birth weight) and 30 controls were included in the study (7-12 years). Results: Cortical thickness was lower in bilateral frontal and left parietal regions and higher in left temporal gyri in preterms compared to controls. However, these differences depended on age. In preterms, age correlated negatively with cortical thickness in right frontal, parietal and inferior temporal regions. Accordingly, cortical thickness was higher in young compared to old preterms in bilateral frontal, parietal and temporal regions. In controls, age was not associated with cortical thickness. Conclusion: In preterms, cortical thinning still seems to occur between the age of 7 and 12 years, mainly in frontal and parietal areas whereas in controls, a substantial part of cortical thinning appears to be completed before they reach the age of 7 years. These data indicate slower cortical thinning in preterms than in controls.

Altered structure of cortical sulci in gilles de la Tourette syndrome: Further support for abnormal brain development.

Gilles de la Tourette syndrome is a neurodevelopmental disorder characterized by the presence of motor and vocal tics. We hypothesized that patients with this syndrome would present an aberrant pattern of cortical formation, which could potentially reflect global alterations of brain development. Using 3 Tesla structural neuroimaging, we compared sulcal depth, opening, and length and thickness of sulcal gray matter in 52 adult patients and 52 matched controls. Cortical sulci were automatically reconstructed and identified over the whole brain, using BrainVisa software. We focused on frontal, parietal, and temporal cortical regions, in which abnormal structure and functional activity were identified in previous neuroimaging studies. Partial correlation analysis with age, sex, and treatment as covariables of noninterest was performed amongst relevant clinical and neuroimaging variables in patients. Patients with Gilles de la Tourette syndrome showed lower depth and reduced thickness of gray matter in the pre- and post-central as well as superior, inferior, and internal frontal sulci. In patients with associated obsessive-compulsive disorder, additional structural changes were found in temporal, insular, and olfactory sulci. Crucially, severity of tics and of obsessive-compulsive disorder measured by Yale Global Tic severity scale and Yale-Brown Obsessive-Compulsive scale, respectively, correlated with structural sulcal changes in sensorimotor, temporal, dorsolateral prefrontal, and middle cingulate cortical areas. Patients with Gilles de la Tourette syndrome displayed an abnormal structural pattern of cortical sulci, which correlated with severity of clinical symptoms. Our results provide further evidence of abnormal brain development in GTS. © 2015 International Parkinson and Movement Disorder Society.

Implant-supported mandibular overdentures and cortical bone formation: clinical and radiographic results

PURPOSE: The aim of this study was to evaluate the hard and soft tissue parameters around implants supporting overdentures and the possible influence of increased periimplant bone density (IPBD) on implant success. MATERIALS AND METHODS: A total of 44 dental implants placed in the mandible of 12 patients were included in the study. Implants were divided in 2 groups in relation to the optically detected IPBD. Periimplant clinical and radiographic variables were collected over the period of 5 years. RESULTS: Periimplant clinical and radiographic parameters for all implants did not change significantly throughout the observation period (P > 0.05). Significant differences were observed between implants with and without IPBD for periimplant soft tissue parameters and Periotest values (P < 0.05). Implants with and without IPBD at 5-year control showed mean bone loss of 0.04 ± 0.48 mm and 0.55 ± 0.96 mm, respectively (P = 0.026). All density values decreased throughout the observation period, except maximal values for implants with IPBD that overcome the initial values at the 5-year control. CONCLUSIONS: Implants supporting overdentures were clinically successful over the period of follow-up. IPBD may be related to the maintenance of the periimplant bone level.

Ecological speciation and phenotypic plasticity affect ecosystems

Phenotypic differences among closely related populations and species can cause contrasting effects on ecosystems; however, it is unknown whether such effects result from genetic divergence, phenotypic plasticity, or both. To test this, we reared sympatric limnetic and benthic species of whitefish from a young adaptive radiation in a common garden, where the benthic species was raised on two distinct food types. We then used these fish in a mesocosm experiment to test for contrasting ecosystem effects of closely related species and of plastically induced differences within a species. We found that strong contrasting ecosystem effects resulted more frequently from genetic divergence, although they were not stronger overall than those resulting from phenotypic plasticity. Overall, our results provide evidence that genetically based differences among closely related species that evolved during a young adaptive radiation can affect ecosystems, and that phenotypic plasticity can modify the ecosystem effects of such species.

Disentangling the role of phenotypic plasticity and genetic divergence in contemporary ecotype formation during a biological invasion

The occurrence of contemporary ecotype formation through adaptive divergence of populations within the range of an invasive species typically requires standing genetic variation but can be facilitated by phenotypic plasticity. The relative contributions of both of these to adaptive trait differentiation have rarely been simultaneously quantified in recently diverging vertebrate populations. Here we study a case of intraspecific divergence into distinct lake and stream ecotypes of threespine stickleback that evolved in the past 140 years within the invasive range in Switzerland. Using a controlled laboratory experiment with full-sib crosses and treatments mimicking a key feature of ecotypic niche divergence, we test if the phenotypic divergence that we observe in the wild results from phenotypic plasticity or divergent genetic predisposition. Our experimental groups show qualitatively similar phenotypic divergence as those observed among wild adults. The relative contribution of plasticity and divergent genetic predisposition differs among the traits studied, with traits related to the biomechanics of feeding showing a stronger genetic predisposition, whereas traits related to locomotion are mainly plastic. These results implicate that phenotypic plasticity and standing genetic variation interacted during contemporary ecotype formation in this case.