Amputation in adults is associated with an extensive remapping of cortical topography in primary and secondary sensorimotor areas. Here, we used tactile residual limb stimulation and 3T functional ...magnetic resonance imaging in humans to investigate functional connectivity changes in the sensorimotor network of patients with long-term lower limb traumatic amputations with phantom sensation, but without pain. We found a pronounced reduction of inter-hemispheric functional connectivity between homologous sensorimotor cortical regions in amputees, including the primary (S1) and secondary (S2) somatosensory areas, and primary (M1) and secondary (M2) motor areas. We additionally observed an intra-hemispheric increased functional connectivity between primary and secondary somatosensory regions, and between the primary and premotor areas, contralateral to amputation. These functional connectivity changes in specialized small-scale sensory-motor networks improve our understanding of the functional impact of lower limb amputation in the brain. Our findings in a selective group of patients with phantom limb sensations, but without pain suggest that disinhibition of neural inputs following traumatic limb amputation disrupts sensorimotor topology, unbalancing functional brain network organization. These findings step up the description of brain plasticity related with phantom sensations by showing that pain is not critical for sensorimotor network changes after peripheral injury.
Abstract Background The medial forebrain bundle (MFB) is a key structure of the reward system and connects the ventral tegmental area (VTA) with the nucleus accumbens (NAcc), the medial and lateral ...orbitofrontal cortex (mOFC, lOFC) and the dorsolateral prefrontal cortex (dlPFC). Previous diffusion tensor imaging (DTI) studies in major depressive disorder point to white matter alterations of regions which may be incorporated in the MFB. Therefore, it was the aim of our study to probe white matter integrity of the MFB using a DTI-based probabilistic fibre tracking approach. Methods 22 patients with major depressive disorder (MDD) (12 melancholic-MDD patients, 10 non-melancholic-MDD patients) and 21 healthy controls underwent DTI scans. We used a bilateral probabilistic fibre tracking approach to extract pathways between the VTA and NACC, mOFC, lOFC, dlPFC respectively. Mean fractional anisotropy (FA) values were used to compare structural connectivity between groups. Results Mean-FA did not differ between healthy controls and all MDD patients. Compared to healthy controls melancholic MDD-patients had reduced mean-FA in right VTA-lOFC and VTA-dlPFC connections. Furthermore, melancholic-MDD patients had lower mean-FA than non-melancholic MDD-patients in the right VTA-lOFC connection. Mean-FA of these pathways correlated negatively with depression scale rating scores. Limitations Due to the small sample size and heterogeneous age group comparisons between melancholic and non-melancholic MDD-patients should be regarded as preliminary. Conclusions Our results suggest that the melancholic subtype of MDD is characterized by white matter microstructure alterations of the MFB. White matter microstructure is associated with both depression severity and anhedonia.
Abstract Altered frontal white matter integrity has been reported in major depression. Still, the behavioral correlates of these alterations are not established. In healthy subjects, motor activity ...correlated with white matter integrity in the motor system. To explore the relation of white matter integrity and motor activity in major depressive disorder, we investigated 21 medicated patients with major depressive disorder and 21 matched controls using diffusion tensor imaging and wrist actigraphy at the same day. Patients had lower activity levels (AL) compared with controls. Fractional anisotropy (FA) differed between groups in frontal white matter regions and the posterior cingulum. AL was linearly associated with white matter integrity in two clusters within the motor system. Controls had an exclusive positive association of FA and AL in white matter underneath the right dorsal premotor cortex. Only patients had a positive association within the posterior cingulum. Furthermore, patients had negative associations of FA and AL underneath the left primary motor cortex and within the left parahippocampal gyrus white matter. These differences in the associations between structure and behavior may contribute to well-known impaired motor planning or gait disturbances in major depressive disorder. Therefore, signs of psychomotor slowing in major depressive disorder may be linked to changes of the white matter integrity of the motor system.
Alterations of brain structure and function have been associated with psychomotor retardation in major depressive disorder (MDD). However, the association of motor behaviour and white matter ...integrity of motor pathways in MDD is unclear. The aim of the present study was to first investigate structural connectivity of white matter motor pathways in MDD. Second, we explore the relation of objectively measured motor activity and white matter integrity of motor pathways in MDD. Therefore, 21 patients with MDD and 21 healthy controls matched for age, gender, education and body mass index underwent diffusion tensor imaging and 24 hour actigraphy (measure of the activity level) the same day. Applying a probabilistic fibre tracking approach we extracted connection pathways between the dorsolateral prefrontal cortex (dlPFC), the rostral anterior cingulate cortex (rACC), the pre-supplementary motor area (pre-SMA), the SMA-proper, the primary motor cortex (M1), the caudate nucleus, the putamen, the pallidum and the thalamus. Patients had lower activity levels and demonstrated increased mean diffusivity (MD) in pathways linking left pre-SMA and SMA-proper, and right SMA-proper and M1. Exploratory analyses point to a positive association of activity level and mean-fractional anisotropy in the right rACC-pre-SMA connection in MDD. Only MDD patients with low activity levels had a negative linear association of activity level and mean-MD in the left dlPFC-pre-SMA connection. Our results point to structural alterations of cortico-cortical white matter motor pathways in MDD. Altered white matter organisation of rACC-pre-SMA and dlPFC-pre-SMA pathways may contribute to movement initiation in MDD.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract
Airborne laser scanning (ALS) data are routinely used to estimate and map structure-related forest inventory variables. The further development, refinement and evaluation of methods to ...derive forest inventory variables from ALS data require extensive datasets of forest stand information on an individual tree-level and corresponding ALS data. A cost-efficient method to obtain such datasets is the combination of virtual forest stands with a laser scanning simulator. We present an approach to simulate ALS data of forest stands by combining forest inventory information, a tree point cloud database and the laser scanning simulation framework HELIOS++. ALS data of six 1-ha plots were simulated and compared to real ALS data of these plots. The synthetic 3D representations of the forest stands were composed of real laser scanning point clouds of individual trees that were acquired by an uncrewed aerial vehicle (UAV), and, for comparison, simplified tree models with cylindrical stems and spheroidal crowns. The simulated ALS point clouds of the six plots were compared with the real point clouds based on canopy cover, height distribution of returns and several other point cloud metrics. In addition, the performance of biomass models trained using these synthetic data was evaluated. The comparison revealed that, in general, both the real tree models and the simplified tree models can be used to generate synthetic data. The results differed for the different study sites and depending on whether all returns or only first returns were considered. The measure of canopy cover was better represented by the data of the simplified tree models, whereas the height distribution of the returns was – for most of the study sites – better represented by the real tree model data. Training biomass models with metrics derived from the real tree model data led to an overestimation of biomass, while using metrics of the simplified tree model data resulted in an underestimation of biomass. Still, the accuracy of models trained with simulated data was only slightly lower compared to models trained with real ALS data. Our results suggest that the presented approach can be used to generate ALS data that are sufficiently realistic for many applications. The synthetic data may be used to develop new or refine existing ALS-based forest inventory methods, to systematically investigate the relationship between point cloud metrics and forest inventory variables and to analyse how this relationship is affected by laser scanning acquisition settings and field reference data characteristics.
Abstract Despite the use of actigraphy in depression research, the association of depression ratings and quantitative motor activity remains controversial. In addition, the impact of recurring ...episodes on motor activity is uncertain. In 76 medicated inpatients with major depression (27 with a first episode, 49 with recurrent episodes), continuous wrist actigraphy for 24 h and scores on the Hamilton Depression Rating Scale (HAMD) were obtained. In addition, 10 subjects of the sample wore the actigraph over a period of 5 days, in order to assess the reliability of a 1-day measurement. Activity levels were stable over 5 consecutive days. Actigraphic parameters did not differ between patients with a first or a recurrent episode, and quantitative motor activity failed to correlate with the HAMD total score. However, of the motor-related single items of the HAMD, the item activities was associated with motor activity parameters, while the items agitation and retardation were not. Actigraphy is consistent with clinical observation for the item activities . Expert raters may not correctly rate the motor aspects of retardation and agitation in major depression.
Abstract
Airborne laser scanning data are increasingly used to predict forest biomass over large areas. Biomass information cannot be derived directly from airborne laser scanning data; therefore, ...field measurements of forest plots are required to build regression models. We tested whether simulated laser scanning data of virtual forest plots could be used to train biomass models and thereby reduce the amount of field measurements required. We compared the performance of models that were trained with (i) simulated data only, (ii) a combination of simulated and real data, (iii) real data collected from different study sites, and (iv) real data collected from the same study site the model was applied to. We additionally investigated whether using a subset of the simulated data instead of using all simulated data improved model performance. The best matching subset of the simulated data was sampled by selecting the simulated forest plot with the highest correlation of the return height distribution profile for each real forest plot. For comparison, a randomly selected subset was evaluated. Models were tested on four forest sites located in Poland, the Czech Republic, and Canada. Model performance was assessed by root mean squared error (RMSE), squared Pearson correlation coefficient (r$^{2}$), and mean error (ME) of observed and predicted biomass. We found that models trained solely with simulated data did not achieve the accuracy of models trained with real data (RMSE increase of 52–122 %, r$^{2}$ decrease of 4–18 %). However, model performance improved when only a subset of the simulated data was used (RMSE increase of 21–118 %, r$^{2}$ decrease of 5–14 % compared to the real data model), albeit differences in model performance when using the best matching subset compared to using a randomly selected subset were small. Using simulated data for model training always resulted in a strong underprediction of biomass. Extending sparse real training datasets with simulated data decreased RMSE and increased r$^{2}$, as long as no more than 12–346 real training samples were available, depending on the study site. For three of the four study sites, models trained with real data collected from other sites outperformed models trained with simulated data and RMSE and r$^{2}$ were similar to models trained with data from the respective sites. Our results indicate that simulated data cannot yet replace real data but they can be helpful in some sites to extend training datasets when only a limited amount of real data is available.
As urban areas continue to develop and expand, carbon dioxide (CO2) emissions from their energy use are growing exponentially. This has made carbon reduction a global concern. Previous studies have ...provided a limited understanding of carbon budgets because they have used top-down data on a single spatial or temporal scale. In this study, urban spatial and statistical data for metropolitan Tainan in southwestern Taiwan are used to explore inside and outside of the CO2 system of the city and estimate the amount of CO2 emissions from road traffic, the use of electricity and gas in buildings, and the amount of CO2 absorbed by green spaces and water bodies within the system. Innovative annual and monthly carbon budget maps composed of 200×200-m grids are developed for the city through a geographic information system (GIS). An analysis of the highly detailed maps yields the following findings: First, CO2 emissions are concentrated in over-urbanized areas, where the population density is higher than 5000 people/km2. Buildings account for the majority of carbon dioxide emissions (54%) and produced 11% more carbon dioxide in summer than in winter (owing to air-conditioning usage). Second, road traffic is the main source of CO2 emissions for under-urbanized areas (87%), and emissions from this source exhibit insignificant seasonal variation. On the basis of these findings, the carbon budgets of four different over-urbanized areas are formulated and presented on 50×50-m grids. The results suggest that green spaces in these areas absorb limited amounts of carbon dioxide. Therefore, this study assesses the annual and monthly carbon-reduction potential of rooftops equipped with solar panels occupying 30% of their area. The annual carbon-reduction potential for the four areas was 4.5–31.1kgCO2m−2yr−1, and the solar energy replacement rate is higher in winter than in summer. In summary, this study presents carbon budgets in high-resolution grids, quantifies the carbon-reduction potential of rooftops with solar panels, and proposes a reduction strategy for reducing CO2 emissions from urban activities to improve the sustainability of urban areas and their environs and inform urban planning and climate change adaptation.
•BHP compositions vary between soil horizons and permafrost structures.•Structural diversity correlates with lower pH and higher organic carbon content.•BHP results agree with 16S rRNA based ...community structure.
Bacteriohopanepolyols (BHPs) are biomarkers providing taxonomically and environmentally diagnostic information. BHPs may help to unravel the composition of bacterial communities residing in recent as well as ancient permafrost soils and sediments and also provide information on associated environmental conditions. However, detailed data on their distribution in the heterogeneous Arctic environment are scarce. The distribution and structural diversity of BHPs were studied in the annually thawing (active) layer of three different sites in the polygonal tundra of the Lena Delta in the Siberian Arctic. Variations between permafrost structures and soil horizons caused by differences in the physical and chemical soil properties were observed. C and N content is significantly correlated with the BHP composition so that the highest BHP concentrations and greatest structural diversity occur in the uppermost organic soil horizons, which consist mainly of fresh or little degraded plant material. Furthermore, statistical analyses reveal that higher abundances of adenosylhopane-type soil marker BHPs are linked to higher soil pH values. Small scale environmental controls on BHP distributions are reflected by amine-functionalised BHPs from methanotrophic bacteria only occurring in the water-saturated, oxygen-depleted polygon centres and by soil marker BHPs, which are significantly more abundant in the well aerated polygon rims than in the centres. In contrast, C-2 methylated BHPs, putative indicators of plant-bacterial interactions, are present in all soil horizons and permafrost structures and their relative distribution is not systematically linked to soil properties. Overall, lipid-based results agree with published 16S rRNA based community structure assessments highlighting the usefulness of BHPs to represent bacterial populations in recent and ancient permafrost soils.
The antibiotic strepturidin (1) was isolated from the microorganism Streptomyces albus DSM 40763, and its structure elucidated by spectroscopic methods and chemical degradation studies. The ...determination of the relative and absolute stereocenters was partially achieved using chiral GC/EI-MS analysis and microderivatization by acetal ring formation and subsequent 2D-NMR analysis of key (1)H,(1)H-NOESY NMR correlations and extraction of (1)H,(13)C coupling constants from (1)H,(13)C-HMBC NMR spectra. Based on these results, a biosynthesis model was proposed.
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