TY - JOUR A1 - Kaiser, M. A1 - Ellerbrock, Ruth H. A1 - Wulf, M. A1 - Dultz, S. A1 - Hierath, C. A1 - Sommer, M. T1 - The influence of mineral characteristics on organic matter content, composition, and stability of topsoils under long-term arable and forest land use JF - Journal of geophysical research : Biogeosciences N2 - In this study, we analyzed the influence of soil mineral characteristics (e. g., clay concentration and mineralogical composition, iron and aluminum oxide concentration and crystallinity, specific surface area, and exchangeable cation concentration) on (i) organic carbon (OC) content (kg m(-2)) and (ii) the concentration (g kg(-1)), composition, and stability of the mineral-associated organic matter (OM) of arable and forest topsoils. We selected seven soil types with different mineral characteristics for this study. For each soil type, samples were taken from topsoils of a deciduous forest and an adjacent arable site. The arable and forest sites have been used continuously for more than 100 years. Na-pyrophosphate soluble OM fractions (OM(PY)), representing mineral-associated OM, were extracted, analyzed for OC and C-14 concentrations, and characterized by FTIR spectroscopy. For the forest and arable topsoils, a linear relationship was found between the OC content and exchangeable Ca. For the arable topsoils (pH 6.7-7.5), correlation analyses indicated that the OCPY concentration increased with an increase in oxalate soluble Fe and Al, exchangeable Ca, and Na-pyrophosphate soluble Mg and Fe concentrations. The stability of OM(PY) determined by the C-14 measurements of the near-neutral arable topsoils was shown to increase with the specific surface area and the concentration of exchangeable Ca. For the acidic forest topsoils (pH < 5), the stability of OM(PY) was found to increase as the pH, and the concentration of C=O groups and Na-pyrophosphate soluble Mg increase. Y1 - 2012 U6 - https://doi.org/10.1029/2011JG001712 SN - 0148-0227 VL - 117 IS - 4 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Pohl, M. A1 - Hoffmann, M. A1 - Hagemann, U. A1 - Giebels, M. A1 - Borraz, Elisa Albiac A1 - Sommer, Michael A1 - Augustin, Jürgen T1 - Dynamic C and N stocks - key factors controlling the C gas exchange of maize in heterogenous peatland JF - Biogeosciences N2 - The drainage and cultivation of fen peatlands create complex small-scale mosaics of soils with extremely variable soil organic carbon (SOC) stocks and groundwater levels (GWLs). To date, the significance of such sites as sources or sinks for greenhouse gases such as CO2 and CH4 is still unclear, especially if the sites are used for cropland. As individual control factors such as GWL fail to account for this complexity, holistic approaches combining gas fluxes with the underlying processes are required to understand the carbon (C) gas exchange of drained fens. It can be assumed that the stocks of SOC and N located above the variable GWL - defined as dynamic C and N stocks - play a key role in the regulation of the plant- and microbially mediated CO2 fluxes in these soils and, inversely, for CH4. To test this assumption, the present study analysed the C gas exchange (gross primary production - GPP; ecosystem respiration - R-eco; net ecosystem exchange - NEE; CH4) of maize using manual chambers for 4 years. The study sites were located near Paulinenaue, Germany, where we selected three soil types representing the full gradient of GWL and SOC stocks (0-1 m) of the landscape: (a) Haplic Arenosol (AR; 8 kg C m(-2)); (b) Mollic Gleysol (GL; 38 kg C m(-2)); and (c) Hemic Histosol (HS; 87 kg C m(-2)). Daily GWL data were used to calculate dynamic SOC (SOCdyn) and N (N-dyn) stocks. Average annual NEE differed considerably among sites, ranging from 47 +/- 30 g C m(-2) yr(-1) in AR to -305 +/- 123 g C m(-2) yr(-1) in GL and -127 +/- 212 g C m(-2) yr(-1) in HS. While static SOC and N stocks showed no significant effect on C fluxes, SOCdyn and N-dyn and their interaction with GWL strongly influenced the C gas exchange, particularly NEE and the GPP : R-eco ratio. Moreover, based on nonlinear regression analysis, 86% of NEE variability was explained by GWL and SOCdyn. The observed high relevance of dynamic SOC and N stocks in the aerobic zone for plant and soil gas exchange likely originates from the effects of GWL-dependent N availability on C formation and transformation processes in the plant-soil system, which promote CO2 input via GPP more than CO2 emission via R-eco. The process-oriented approach of dynamic C and N stocks is a promising, potentially generalisable method for system-oriented investigations of the C gas exchange of groundwater-influenced soils and could be expanded to other nutrients and soil characteristics. However, in order to assess the climate impact of arable sites on drained peatlands, it is always necessary to consider the entire range of groundwater-influenced mineral and organic soils and their respective areal extent within the soil landscape. Y1 - 2015 U6 - https://doi.org/10.5194/bg-12-2737-2015 SN - 1726-4170 SN - 1726-4189 VL - 12 IS - 9 SP - 2737 EP - 2752 PB - Copernicus CY - Göttingen ER - TY - GEN A1 - Pohl, Madlen A1 - Hoffmann, M. A1 - Hagemann, Ulrike A1 - Giebels, M. A1 - Albiac Borraz, E. A1 - Sommer, Michael A1 - Augustin, Jürgen T1 - Dynamic C and N stocks BT - key factors controlling the C gas exchange of maize in heterogenous peatland T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - The drainage and cultivation of fen peatlands create complex small-scale mosaics of soils with extremely variable soil organic carbon (SOC) stocks and groundwater levels (GWLs). To date, the significance of such sites as sources or sinks for greenhouse gases such as CO2 and CH4 is still unclear, especially if the sites are used for cropland. As individual control factors such as GWL fail to account for this complexity, holistic approaches combining gas fluxes with the underlying processes are required to understand the carbon (C) gas exchange of drained fens. It can be assumed that the stocks of SOC and N located above the variable GWL - defined as dynamic C and N stocks - play a key role in the regulation of the plant- and microbially mediated CO2 fluxes in these soils and, inversely, for CH4. To test this assumption, the present study analysed the C gas exchange (gross primary production - GPP; ecosystem respiration - R-eco; net ecosystem exchange - NEE; CH4) of maize using manual chambers for 4 years. The study sites were located near Paulinenaue, Germany, where we selected three soil types representing the full gradient of GWL and SOC stocks (0-1 m) of the landscape: (a) Haplic Arenosol (AR; 8 kg C m(-2)); (b) Mollic Gleysol (GL; 38 kg C m(-2)); and (c) Hemic Histosol (HS; 87 kg C m(-2)). Daily GWL data were used to calculate dynamic SOC (SOCdyn) and N (N-dyn) stocks. Average annual NEE differed considerably among sites, ranging from 47 +/- 30 g C m(-2) yr(-1) in AR to -305 +/- 123 g C m(-2) yr(-1) in GL and -127 +/- 212 g C m(-2) yr(-1) in HS. While static SOC and N stocks showed no significant effect on C fluxes, SOCdyn and N-dyn and their interaction with GWL strongly influenced the C gas exchange, particularly NEE and the GPP : R-eco ratio. Moreover, based on nonlinear regression analysis, 86% of NEE variability was explained by GWL and SOCdyn. The observed high relevance of dynamic SOC and N stocks in the aerobic zone for plant and soil gas exchange likely originates from the effects of GWL-dependent N availability on C formation and transformation processes in the plant-soil system, which promote CO2 input via GPP more than CO2 emission via R-eco. The process-oriented approach of dynamic C and N stocks is a promising, potentially generalisable method for system-oriented investigations of the C gas exchange of groundwater-influenced soils and could be expanded to other nutrients and soil characteristics. However, in order to assess the climate impact of arable sites on drained peatlands, it is always necessary to consider the entire range of groundwater-influenced mineral and organic soils and their respective areal extent within the soil landscape. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 496 KW - soil organic-matter KW - Zea-mays L. KW - term management impacts KW - carbon-dioxide exchange KW - net ecosystem exchange KW - nitrogen-fertilization KW - water-table KW - northeast germany KW - CO2 fluxes KW - mineral fertilization Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-408184 SN - 1866-8372 IS - 496 ER - TY - JOUR A1 - Garbusow, Maria A1 - Schad, Daniel A1 - Sebold, Miriam Hannah A1 - Friedel, Eva A1 - Bernhardt, Nadine A1 - Koch, Stefan P. A1 - Steinacher, Bruno A1 - Kathmann, Norbert A1 - Geurts, Dirk E. M. A1 - Sommer, Christian A1 - Mueller, Dirk K. A1 - Nebe, Stephan A1 - Paul, Soeren A1 - Wittchen, Hans-Ulrich A1 - Zimmermann, Ulrich S. A1 - Walter, Henrik A1 - Smolka, Michael N. A1 - Sterzer, Philipp A1 - Rapp, Michael Armin A1 - Huys, Quentin J. M. A1 - Schlagenhauf, Florian A1 - Heinz, Andreas T1 - Pavlovian-to-instrumental transfer effects in the nucleus accumbens relate to relapse in alcohol dependence JF - Addiction biology N2 - In detoxified alcohol-dependent patients, alcohol-related stimuli can promote relapse. However, to date, the mechanisms by which contextual stimuli promote relapse have not been elucidated in detail. One hypothesis is that such contextual stimuli directly stimulate the motivation to drink via associated brain regions like the ventral striatum and thus promote alcohol seeking, intake and relapse. Pavlovian-to-Instrumental-Transfer (PIT) may be one of those behavioral phenomena contributing to relapse, capturing how Pavlovian conditioned (contextual) cues determine instrumental behavior (e.g. alcohol seeking and intake). We used a PIT paradigm during functional magnetic resonance imaging to examine the effects of classically conditioned Pavlovian stimuli on instrumental choices in n=31 detoxified patients diagnosed with alcohol dependence and n=24 healthy controls matched for age and gender. Patients were followed up over a period of 3 months. We observed that (1) there was a significant behavioral PIT effect for all participants, which was significantly more pronounced in alcohol-dependent patients; (2) PIT was significantly associated with blood oxygen level-dependent (BOLD) signals in the nucleus accumbens (NAcc) in subsequent relapsers only; and (3) PIT-related NAcc activation was associated with, and predictive of, critical outcomes (amount of alcohol intake and relapse during a 3 months follow-up period) in alcohol-dependent patients. These observations show for the first time that PIT-related BOLD signals, as a measure of the influence of Pavlovian cues on instrumental behavior, predict alcohol intake and relapse in alcohol dependence. KW - human Pavlovian-to-instrumental transfer KW - nucleus accumbens KW - relapse in alcohol use disorder Y1 - 2016 U6 - https://doi.org/10.1111/adb.12243 SN - 1355-6215 SN - 1369-1600 VL - 21 SP - 719 EP - 731 PB - Wiley-Blackwell CY - Hoboken ER - TY - GEN A1 - Garbusow, Maria A1 - Nebe, Stephan A1 - Sommer, Christian A1 - Kuitunen-Paul, Sören A1 - Sebold, Miriam Hannah A1 - Schad, Daniel A1 - Friedel, Eva A1 - Veer, Ilya M. A1 - Wittchen, Hans-Ulrich A1 - Rapp, Michael Armin A1 - Ripke, Stephan A1 - Walter, Henrik A1 - Huys, Quentin J. M. A1 - Schlagenhauf, Florian A1 - Smolka, Michael N. A1 - Heinz, Andreas T1 - Pavlovian-To-Instrumental Transfer and Alcohol Consumption in Young Male Social Drinkers BT - Behavioral, Neural and Polygenic Correlates T2 - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe N2 - In animals and humans, behavior can be influenced by irrelevant stimuli, a phenomenon called Pavlovian-to-instrumental transfer (PIT). In subjects with substance use disorder, PIT is even enhanced with functional activation in the nucleus accumbens (NAcc) and amygdala. While we observed enhanced behavioral and neural PIT effects in alcohol-dependent subjects, we here aimed to determine whether behavioral PIT is enhanced in young men with high-risk compared to low-risk drinking and subsequently related functional activation in an a-priori region of interest encompassing the NAcc and amygdala and related to polygenic risk for alcohol consumption. A representative sample of 18-year old men (n = 1937) was contacted: 445 were screened, 209 assessed: resulting in 191 valid behavioral, 139 imaging and 157 genetic datasets. None of the subjects fulfilled criteria for alcohol dependence according to the Diagnostic and Statistical Manual of Mental Disorders-IV-TextRevision (DSM-IV-TR). We measured how instrumental responding for rewards was influenced by background Pavlovian conditioned stimuli predicting action-independent rewards and losses. Behavioral PIT was enhanced in high-compared to low-risk drinkers (b = 0.09, SE = 0.03, z = 2.7, p < 0.009). Across all subjects, we observed PIT-related neural blood oxygen level-dependent (BOLD) signal in the right amygdala (t = 3.25, p(SVC) = 0.04, x = 26, y = -6, z = -12), but not in NAcc. The strength of the behavioral PIT effect was positively correlated with polygenic risk for alcohol consumption (r(s) = 0.17, p = 0.032). We conclude that behavioral PIT and polygenic risk for alcohol consumption might be a biomarker for a subclinical phenotype of risky alcohol consumption, even if no drug-related stimulus is present. The association between behavioral PIT effects and the amygdala might point to habitual processes related to out PIT task. In non-dependent young social drinkers, the amygdala rather than the NAcc is activated during PIT; possible different involvement in association with disease trajectory should be investigated in future studies. T3 - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - 841 KW - Pavlovian-to-instrumental transfer KW - amygdala KW - alcohol KW - polygenic risk KW - high risk drinkers Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-473280 SN - 1866-8364 IS - 841 ER - TY - JOUR A1 - Garbusow, Maria A1 - Nebe, Stephan A1 - Sommer, Christian A1 - Kuitunen-Paul, Sören A1 - Sebold, Miriam Hannah A1 - Schad, Daniel A1 - Friedel, Eva A1 - Veer, Ilya M. A1 - Wittchen, Hans-Ulrich A1 - Rapp, Michael Armin A1 - Ripke, Stephan A1 - Walter, Henrik A1 - Huys, Quentin J. M. A1 - Schlagenhauf, Florian A1 - Smolka, Michael N. A1 - Heinz, Andreas T1 - Pavlovian-To-Instrumental Transfer and Alcohol Consumption in Young Male Social Drinkers BT - Behavioral, Neural and Polygenic Correlates JF - Journal of Clinical Medicine N2 - In animals and humans, behavior can be influenced by irrelevant stimuli, a phenomenon called Pavlovian-to-instrumental transfer (PIT). In subjects with substance use disorder, PIT is even enhanced with functional activation in the nucleus accumbens (NAcc) and amygdala. While we observed enhanced behavioral and neural PIT effects in alcohol-dependent subjects, we here aimed to determine whether behavioral PIT is enhanced in young men with high-risk compared to low-risk drinking and subsequently related functional activation in an a-priori region of interest encompassing the NAcc and amygdala and related to polygenic risk for alcohol consumption. A representative sample of 18-year old men (n = 1937) was contacted: 445 were screened, 209 assessed: resulting in 191 valid behavioral, 139 imaging and 157 genetic datasets. None of the subjects fulfilled criteria for alcohol dependence according to the Diagnostic and Statistical Manual of Mental Disorders-IV-TextRevision (DSM-IV-TR). We measured how instrumental responding for rewards was influenced by background Pavlovian conditioned stimuli predicting action-independent rewards and losses. Behavioral PIT was enhanced in high-compared to low-risk drinkers (b = 0.09, SE = 0.03, z = 2.7, p < 0.009). Across all subjects, we observed PIT-related neural blood oxygen level-dependent (BOLD) signal in the right amygdala (t = 3.25, p(SVC) = 0.04, x = 26, y = -6, z = -12), but not in NAcc. The strength of the behavioral PIT effect was positively correlated with polygenic risk for alcohol consumption (r(s) = 0.17, p = 0.032). We conclude that behavioral PIT and polygenic risk for alcohol consumption might be a biomarker for a subclinical phenotype of risky alcohol consumption, even if no drug-related stimulus is present. The association between behavioral PIT effects and the amygdala might point to habitual processes related to out PIT task. In non-dependent young social drinkers, the amygdala rather than the NAcc is activated during PIT; possible different involvement in association with disease trajectory should be investigated in future studies. KW - Pavlovian-to-instrumental transfer KW - amygdala KW - alcohol KW - polygenic risk KW - high risk drinkers Y1 - 2019 U6 - https://doi.org/10.3390/jcm8081188 SN - 2077-0383 VL - 8 IS - 8 PB - MDPI CY - Basel ER - TY - JOUR A1 - van der Meij, Marijn W. A1 - Temme, Arnaud J. A. M. A1 - Lin, H. S. A1 - Gerke, Horst H. A1 - Sommer, Michael T1 - On the role of hydrologic processes in soil and landscape evolution modeling BT - concepts, complications and partial solutions JF - Earth science reviews : the international geological journal bridging the gap between research articles and textbooks N2 - The ability of water to transport and transform soil materials is one of the main drivers of soil and landscape development. In turn, soil and landscape properties determine how water is distributed in soil landscapes. Understanding the complex dynamics of this co-evolution of soils, landscapes and the hydrological system is fundamental in adapting land management to changes in climate. Soil-Landscape Evolution Models (SLEMs) are used to simulate the development and evolution of soils and landscapes. However, many hydrologic processes, such as preferential flow and subsurface lateral flow, are currently absent in these models. This limits the applicability of SLEMs to improve our understanding of feedbacks in the hydro-pedo-geomorphological system. Implementation of these hydrologic processes in SLEMs faces several complications related to calculation demands, limited methods for linking pedogenic and hydrologic processes, and limited data on quantification of changes in the hydrological system over time. In this contribution, we first briefly review processes and feedbacks in soil-landscape-hydrological systems. Next, we elaborate on the development required to include these processes in SLEMs. We discuss the state-of-the-art knowledge, identify complications, give partial solutions and suggest important future development. The main requirements for incorporating hydrologic processes in SLEMs are: (1) designing a model framework that can deal with varying timescales for different sets of processes, (2) developing and implementing methods for simulating pedogenesis as a function of water flow, (3) improving and implementing knowledge on the evolution and dynamics of soil hydraulic properties over different timescales, and (4) improving the database on temporal changes and dynamics of flow paths. Y1 - 2018 U6 - https://doi.org/10.1016/j.earscirev.2018.09.001 SN - 0012-8252 SN - 1872-6828 VL - 185 SP - 1088 EP - 1106 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Fiener, P. A1 - Wilken, F. A1 - Aldana-Jague, E. A1 - Deumlich, D. A1 - Gomez, J. A. A1 - Guzman, G. A1 - Hardy, R. A. A1 - Quinton, J. N. A1 - Sommer, M. A1 - Van Oost, K. A1 - Wexler, R. T1 - Uncertainties in assessing tillage erosion BT - how appropriate are our measuring techniques? JF - Geomorphology : an international journal on pure and applied geomorphology N2 - Tillage erosion on arable land is a very important process leading to a net downslope movement of soil and soil constitutes. Tillage erosion rates are commonly in the same order of magnitude as water erosion rates and can be even higher, especially under highly mechanized agricultural soil management. Despite its prevalence and magnitude, tillage erosion is still understudied compared to water erosion. The goal of this study was to bring together experts using different techniques to determine tillage erosion and use the different results to discuss and quantify uncertainties associated with tillage erosion measurements. The study was performed in northeastern Germany on a 10 m by 50 m plot with a mean slope of 8%. Tillage erosion was determined after two sequences of seven tillage operations. Two different micro-tracers (magnetic iron oxide mixed with soil and fluorescent sand) and one macro-tracer (passive radio-frequency identification transponders (RFIDs), size: 4 x 22 mm) were used to directly determine soil fluxes. Moreover, tillage induced changes in topography were measured for the entire plot with two different terrestrial laser scanners and an unmanned aerial system for structure from motion topography analysis. Based on these elevation differences, corresponding soil fluxes were calculated. The mean translocation distance of all techniques was 0.57 m per tillage pass, with a relatively wide range of mean soil translocation distances ranging from 039 to 0.72 m per pass. A benchmark technique could not be identified as all used techniques have individual error sources, which could not be quantified. However, the translocation distances of the macro-tracers used were consistently smaller than the translocation distances of the micro-tracers (mean difference = -26 +/- 12%), which questions the widely used assumption of non-selective soil transport via tillage operations. This study points out that tillage erosion measurements, carried out under almost optimal conditions, are subject to major uncertainties that are far from negligible. (C) 2018 Elsevier B.V. All rights reserved. KW - Tillage erosion KW - Tracer KW - UAS KW - TLS KW - Method comparison KW - Measurement uncertainty Y1 - 2018 U6 - https://doi.org/10.1016/j.geomorph.2017.12.031 SN - 0169-555X SN - 1872-695X VL - 304 SP - 214 EP - 225 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Muhl, Rika M. W. A1 - Roelke, Daniel L. A1 - Zohary, Tamar A1 - Moustaka-Gouni, Maria A1 - Sommer, Ulrich A1 - Borics, Gabor A1 - Gaedke, Ursula A1 - Withrow, Frances G. A1 - Bhattacharyya, Joydeb T1 - Resisting annihilation BT - relationships between functional trait dissimilarity, assemblage competitive power and allelopathy JF - Ecology letters N2 - Allelopathic species can alter biodiversity. Using simulated assemblages that are characterised by neutrality, lumpy coexistence and intransitivity, we explore relationships between within-assemblage competitive dissimilarities and resistance to allelopathic species. An emergent behaviour from our models is that assemblages are more resistant to allelopathy when members strongly compete exploitatively (high competitive power). We found that neutral assemblages were the most vulnerable to allelopathic species, followed by lumpy and then by intransitive assemblages. We find support for our modeling in real-world time-series data from eight lakes of varied morphometry and trophic state. Our analysis of this data shows that a lake's history of allelopathic phytoplankton species biovolume density and dominance is related to the number of species clusters occurring in the plankton assemblages of those lakes, an emergent trend similar to that of our modeling. We suggest that an assemblage's competitive power determines its allelopathy resistance. KW - Allelopathy KW - exploitative competition KW - interference competition KW - intransitivity KW - lumpy coexistence KW - neutrality KW - species supersaturated assemblages Y1 - 2018 U6 - https://doi.org/10.1111/ele.13109 SN - 1461-023X SN - 1461-0248 VL - 21 IS - 9 SP - 1390 EP - 1400 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - van der Meij, Marijn W. A1 - Reimann, Tony A1 - Vornehm, V. K. A1 - Temme, Arnaud J. A. M. A1 - Wallinga, Jakob A1 - van Beek, Roy A1 - Sommer, Michael T1 - Reconstructing rates and patterns of colluvial soil redistribution in agrarian (hummocky) landscapes JF - Earth surface processes and landforms : the journal of the British Geomorphological Research Group N2 - Humans have triggered or accelerated erosion processes since prehistoric times through agricultural practices. Optically stimulated luminescence (OSL) is widely used to quantify phases and rates of the corresponding landscape change, by measuring the last moment of daylight exposure of sediments. However, natural and anthropogenic mixing processes, such as bioturbation and tillage, complicate the use of OSL as grains of different depositional ages become mixed, and grains become exposed to light even long after the depositional event of interest. Instead, OSL determines the stabilization age, indicating when sediments were buried below the active mixing zone. These stabilization ages can cause systematic underestimation when calculating deposition rates. Our focus is on colluvial deposition in a kettle hole in the Uckermark region, northeastern Germany. We took 32 samples from five locations in the colluvium filling the kettle hole to study both spatial and temporal patterns in colluviation. We combined OSL dating with advanced age modelling to determine the stabilization age of colluvial sediments. These ages were combined with an archaeological reconstruction of historical ploughing depths to derive the levels of the soil surface at the moment of stabilization; the deposition depths, which were then used to calculate unbiased deposition rates. We identified two phases of colluvial deposition. The oldest deposits (similar to 5 ka) were located at the fringe of the kettle hole and accumulated relatively slowly, whereas the youngest deposits (<0.3 ka) rapidly filled the central kettle hole with rates of two orders of magnitude higher. We suggest that the latter phase is related to artificial drainage, facilitating accessibility in the central depression for agricultural practices. Our results show the need for numerical dating techniques that take archaeological and soil-geomorphological information into account to identify spatiotemporal patterns of landscape change, and to correctly interpret landscape dynamics in anthropogenically influenced hilly landscapes. (c) 2019 The Authors. Earth Surface Processes and Landforms Published by John Wiley & Sons Ltd. KW - geochronology KW - OSL KW - tillage KW - erosion KW - kettle hole KW - hummocky KW - landscape evolution Y1 - 2019 U6 - https://doi.org/10.1002/esp.4671 SN - 0197-9337 SN - 1096-9837 VL - 44 IS - 12 SP - 2408 EP - 2422 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Chang, Dan A1 - Knapp, Michael A1 - Enk, Jacob A1 - Lippold, Sebastian A1 - Kircher, Martin A1 - Lister, Adrian M. A1 - MacPhee, Ross D. E. A1 - Widga, Christopher A1 - Czechowski, Paul A1 - Sommer, Robert A1 - Hodges, Emily A1 - Stümpel, Nikolaus A1 - Barnes, Ian A1 - Dalén, Love A1 - Derevianko, Anatoly A1 - Germonpré, Mietje A1 - Hillebrand-Voiculescu, Alexandra A1 - Constantin, Silviu A1 - Kuznetsova, Tatyana A1 - Mol, Dick A1 - Rathgeber, Thomas A1 - Rosendahl, Wilfried A1 - Tikhonov, Alexey N. A1 - Willerslev, Eske A1 - Hannon, Greg A1 - Lalueza i Fox, Carles A1 - Joger, Ulrich A1 - Poinar, Hendrik N. A1 - Hofreiter, Michael A1 - Shapiro, Beth T1 - The evolutionary and phylogeographic history of woolly mammoths BT - a comprehensive mitogenomic analysis JF - Scientific reports N2 - Near the end of the Pleistocene epoch, populations of the woolly mammoth (Mammuthus primigenius) were distributed across parts of three continents, from western Europe and northern Asia through Beringia to the Atlantic seaboard of North America. Nonetheless, questions about the connectivity and temporal continuity of mammoth populations and species remain unanswered. We use a combination of targeted enrichment and high-throughput sequencing to assemble and interpret a data set of 143 mammoth mitochondrial genomes, sampled from fossils recovered from across their Holarctic range. Our dataset includes 54 previously unpublished mitochondrial genomes and significantly increases the coverage of the Eurasian range of the species. The resulting global phylogeny confirms that the Late Pleistocene mammoth population comprised three distinct mitochondrial lineages that began to diverge ~1.0–2.0 million years ago (Ma). We also find that mammoth mitochondrial lineages were strongly geographically partitioned throughout the Pleistocene. In combination, our genetic results and the pattern of morphological variation in time and space suggest that male-mediated gene flow, rather than large-scale dispersals, was important in the Pleistocene evolutionary history of mammoths. Y1 - 2017 U6 - https://doi.org/10.1038/srep44585 SN - 2045-2322 VL - 7 PB - Nature Publishing Group CY - London ER - TY - JOUR A1 - Bell, M. J. A1 - Jones, E. A1 - Smith, J. A1 - Smith, P. A1 - Yeluripati, J. A1 - Augustin, Jürgen A1 - Juszczak, R. A1 - Olejnik, J. A1 - Sommer, Michael T1 - Simulation of soil nitrogen, nitrous oxide emissions and mitigation scenarios at 3 European cropland sites using the ECOSSE model JF - Nutrient cycling in agroecosystems N2 - The global warming potential of nitrous oxide (N2O) and its long atmospheric lifetime mean its presence in the atmosphere is of major concern, and that methods are required to measure and reduce emissions. Large spatial and temporal variations means, however, that simple extrapolation of measured data is inappropriate, and that other methods of quantification are required. Although process-based models have been developed to simulate these emissions, they often require a large amount of input data that is not available at a regional scale, making regional and global emission estimates difficult to achieve. The spatial extent of organic soils means that quantification of emissions from these soil types is also required, but will not be achievable using a process-based model that has not been developed to simulate soil water contents above field capacity or organic soils. The ECOSSE model was developed to overcome these limitations, and with a requirement for only input data that is readily available at a regional scale, it can be used to quantify regional emissions and directly inform land-use change decisions. ECOSSE includes the major processes of nitrogen (N) turnover, with material being exchanged between pools of SOM at rates modified by temperature, soil moisture, soil pH and crop cover. Evaluation of its performance at site-scale is presented to demonstrate its ability to adequately simulate soil N contents and N2O emissions from cropland soils in Europe. Mitigation scenarios and sensitivity analyses are also presented to demonstrate how ECOSSE can be used to estimate the impact of future climate and land-use change on N2O emissions. KW - Soil N2O emissions KW - Process-based models KW - Land-use KW - Climate change Y1 - 2012 U6 - https://doi.org/10.1007/s10705-011-9479-4 SN - 1385-1314 VL - 92 IS - 2 SP - 161 EP - 181 PB - Springer CY - Dordrecht ER - TY - JOUR A1 - Sommer, Ulrich A1 - Adrian, Rita A1 - Domis, Lisette Nicole de Senerpont A1 - Elser, James J. A1 - Gaedke, Ursula A1 - Ibelings, Bas A1 - Jeppesen, Erik A1 - Lurling, Miquel A1 - Molinero, Juan Carlos A1 - Mooij, Wolf M. A1 - van Donk, Ellen A1 - Winder, Monika ED - Futuyma, DJ T1 - Beyond the Plankton Ecology Group (PEG) Model mechanisms driving plankton succession JF - Annual review of ecology, evolution, and systematics JF - Annual Review of Ecology Evolution and Systematics N2 - The seasonal succession of plankton is an annually repeated process of community assembly during which all major external factors and internal interactions shaping communities can be studied. A quarter of a century ago, the state of this understanding was described by the verbal plankton ecology group (PEG) model. It emphasized the role of physical factors, grazing and nutrient limitation for phytoplankton, and the role of food limitation and fish predation for zooplankton. Although originally targeted at lake ecosystems, it was also adopted by marine plankton ecologists. Since then, a suite of ecological interactions previously underestimated in importance have become research foci: overwintering of key organisms, the microbial food web, parasitism, and food quality as a limiting factor and an extended role of higher order predators. A review of the impact of these novel interactions on plankton seasonal succession reveals limited effects on gross seasonal biomass patterns, but strong effects on species replacements. KW - lakes KW - oceans KW - seasonal patterns KW - pelagic zone KW - light KW - overwintering KW - grazing KW - parasitism KW - food quality Y1 - 2012 SN - 978-0-8243-1443-9 U6 - https://doi.org/10.1146/annurev-ecolsys-110411-160251 SN - 1543-592X VL - 43 IS - 2-4 SP - 429 EP - 448 PB - Annual Reviews CY - Palo Alto ER - TY - GEN A1 - Sommer, Michael A1 - Augustin, Jürgen A1 - Kleber, M. T1 - Feedbacks of soil erosion on SOC patterns and carbon dynamics in agricultural landscapes-The CarboZALF experiment T2 - Journal of real-time image processing Y1 - 2016 U6 - https://doi.org/10.1016/j.still.2015.09.015 SN - 0167-1987 SN - 1879-3444 VL - 156 SP - 182 EP - 184 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - van der Meij, Marijn W. A1 - Temme, Arnaud J. A. M. A1 - Wallinga, J. A1 - Hierold, W. A1 - Sommer, Michael T1 - Topography reconstruction of eroding landscapes - A case study from a hummocky ground moraine (CarboZALF-D) JF - Geomorphology : an international journal on pure and applied geomorphology N2 - Erosion processes, aggravated by human activity, have a large impact on the spatial variation of soil and topographic properties. Knowledge of the topography prior to human-induced erosion (paleotopography) in naturally stable landscapes is valuable for identifying vulnerable landscape positions and is required as starting point for erosion modelling exercises. However, developing accurate reconstructions of paleotopography provide a major challenge for geomorphologists. Here, we present a set of paleotopographies for a closed kettle hole catchment in north-east Germany (4 ha), obtained through different reconstruction approaches. Current soil and colluvium thickness, estimated from a dataset of 264 soil descriptions using Ordinary Kriging, were used as input for a mass balance, or were compared with a set of undisturbed soil thicknesses to estimate the amount of erosion. The performance of the different approaches was assessed with cross-validation and the count of mispredicted eroded, depositional or stable landscape positions. The paleotopographic reconstruction approach based on the average thickness of undisturbed soils in the study area showed the best performance. This thickness (1.00 m) is comparable to the average undisturbed soil thickness in the region and in line with global correlations of soil thickness as a function of rainfall and initial CaCO3 content. The performance of the different approaches depended more on mispredictions of landscape position due to the assumption of a spatially constant initial soil depth than on small variations in this depth. To conclude, we mention several methodological and practical points of attention for future topography reconstruction studies, concerning data quality and availability, spatial configuration of data and other processes affecting topography. (C) 2017 Elsevier B.V. All rights reserved. KW - Topography reconstruction KW - Erosion KW - Tillage KW - Landscape change Y1 - 2017 U6 - https://doi.org/10.1016/j.geomorph.2017.08.015 SN - 0169-555X SN - 1872-695X VL - 295 SP - 758 EP - 772 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Winck, Flavia V. A1 - Riano-Pachon, Diego M. A1 - Sommer, Frederik A1 - Rupprecht, Jens A1 - Müller-Röber, Bernd T1 - The nuclear proteome of the green alga Chlamydomonas reinhardtii JF - Proteomics N2 - Nuclear proteins play a central role in regulating gene expression. Their identification is important for understanding how the nuclear repertoire changes over time under different conditions. Nuclear proteins are often underrepresented in proteomic studies due to the frequently low abundance of proteins involved in regulatory processes. So far, only few studies describing the nuclear proteome of plant species have been published. Recently, the genome sequence of the unicellular green alga Chlamydomonas reinhardtii has been obtained and annotated, allowing the development of further detailed studies for this organism. However, a detailed description of its nuclear proteome has not been reported so far. Here, we present an analysis of the nuclear proteome of the sequenced Chlamydomonas strain cc503. Using LC-MS/MS, we identified 672 proteins from nuclei isolates with a maximum 1% peptide spectrum false discovery rate. Besides well-known proteins (e.g. histones), transcription factors and other transcriptional regulators (e.g. tubby and HMG) were identified. The presence of protein motifs in nuclear proteins was investigated by computational tools, and specific over-represented protein motifs were identified. This study provides new insights into the complexity of the nuclear environment and reveals novel putative protein targets for further studies of nuclear mechanisms. KW - Nuclear proteomics KW - Plant proteomics KW - Systems biology KW - Transcription factor Y1 - 2012 U6 - https://doi.org/10.1002/pmic.201000782 SN - 1615-9853 VL - 12 IS - 1 SP - 95 EP - 100 PB - Wiley-Blackwell CY - Malden ER - TY - JOUR A1 - Obst, Elisabeth A1 - Schad, Daniel A1 - Huys, Quentin J. M. A1 - Sebold, Miriam Hannah A1 - Nebe, Stephan A1 - Sommer, Christian A1 - Smolka, Michael N. A1 - Zimmermann, Ulrich S. T1 - Drunk decisions BT - Alcohol shifts choice from habitual towards goal-directed control in adolescent intermediate-risk drinkers JF - Journal of Psychopharmacology N2 - Background: Studies in humans and animals suggest a shift from goal-directed to habitual decision-making in addiction. We therefore tested whether acute alcohol administration reduces goal-directed and promotes habitual decision-making, and whether these effects are moderated by self-reported drinking problems. Methods: Fifty-three socially drinking males completed the two-step task in a randomised crossover design while receiving an intravenous infusion of ethanol (blood alcohol level=80 mg%), or placebo. To minimise potential bias by long-standing heavy drinking and subsequent neuropsychological impairment, we tested 18- to 19-year-old adolescents. Results: Alcohol administration consistently reduced habitual, model-free decisions, while its effects on goal-directed, model-based behaviour varied as a function of drinking problems measured with the Alcohol Use Disorders Identification Test. While adolescents with low risk for drinking problems (scoring <8) exhibited an alcohol-induced numerical reduction in goal-directed choices, intermediate-risk drinkers showed a shift away from habitual towards goal-directed decision-making, such that alcohol possibly even improved their performance. Conclusions: We assume that alcohol disrupted basic cognitive functions underlying habitual and goal-directed decisions in low-risk drinkers, thereby enhancing hasty choices. Further, we speculate that intermediate-risk drinkers benefited from alcohol as a negative reinforcer that reduced unpleasant emotional states, possibly displaying a novel risk factor for drinking in adolescence. KW - Computer-assisted Alcohol Infusion System KW - habitual learning KW - model-free and model-based decision-making KW - two-stage Markov decision task KW - subjective response to ethanol KW - drinking problems KW - real-life drinking behaviour Y1 - 2018 U6 - https://doi.org/10.1177/0269881118772454 SN - 0269-8811 SN - 1461-7285 VL - 32 IS - 8 SP - 855 EP - 866 PB - Sage Publ. CY - London ER - TY - GEN A1 - Giraudier, Manon A1 - Ventura-Bort, Carlos A1 - Burger, Andreas M. A1 - Claes, Nathalie A1 - D'Agostini, Martina A1 - Fischer, Rico A1 - Franssen, Mathijs A1 - Kaess, Michael A1 - Koenig, Julian A1 - Liepelt, Roman A1 - Nieuwenhuis, Sander A1 - Sommer, Aldo A1 - Usichenko, Taras A1 - Van Diest, Ilse A1 - von Leupoldt, Andreas A1 - Warren, Christopher Michael A1 - Weymar, Mathias T1 - Evidence for a modulating effect of transcutaneous auricular vagus nerve stimulation (taVNS) on salivary alpha-amylase as indirect noradrenergic marker: A pooled mega-analysis T2 - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe N2 - Background Non-invasive transcutaneous auricular vagus nerve stimulation (taVNS) has received tremendous attention as a potential neuromodulator of cognitive and affective functions, which likely exerts its effects via activation of the locus coeruleus-noradrenaline (LC-NA) system. Reliable effects of taVNS on markers of LC-NA system activity, however, have not been demonstrated yet. Methods The aim of the present study was to overcome previous limitations by pooling raw data from a large sample of ten taVNS studies (371 healthy participants) that collected salivary alpha-amylase (sAA) as a potential marker of central NA release. Results While a meta-analytic approach using summary statistics did not yield any significant effects, linear mixed model analyses showed that afferent stimulation of the vagus nerve via taVNS increased sAA levels compared to sham stimulation (b = 0.16, SE = 0.05, p = 0.001). When considering potential confounders of sAA, we further replicated previous findings on the diurnal trajectory of sAA activity. Conclusion(s) Vagal activation via taVNS increases sAA release compared to sham stimulation, which likely substantiates the assumption that taVNS triggers NA release. Moreover, our results highlight the benefits of data pooling and data sharing in order to allow stronger conclusions in research. T3 - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - 808 KW - Non-invasive vagus nerve stimulation KW - tVNS KW - sAA KW - Noradrenaline KW - Biomarker KW - Data pooling Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-577668 SN - 1866-8364 IS - 808 SP - 1378 EP - 1388 ER - TY - JOUR A1 - Giraudier, Manon A1 - Ventura-Bort, Carlos A1 - Burger, Andreas M. A1 - Claes, Nathalie A1 - D'Agostini, Martina A1 - Fischer, Rico A1 - Franssen, Mathijs A1 - Kaess, Michael A1 - Koenig, Julian A1 - Liepelt, Roman A1 - Nieuwenhuis, Sander A1 - Sommer, Aldo A1 - Usichenko, Taras A1 - Van Diest, Ilse A1 - von Leupoldt, Andreas A1 - Warren, Christopher Michael A1 - Weymar, Mathias T1 - Evidence for a modulating effect of transcutaneous auricular vagus nerve stimulation (taVNS) on salivary alpha-amylase as indirect noradrenergic marker: A pooled mega-analysis JF - Brain Stimulation N2 - Background Non-invasive transcutaneous auricular vagus nerve stimulation (taVNS) has received tremendous attention as a potential neuromodulator of cognitive and affective functions, which likely exerts its effects via activation of the locus coeruleus-noradrenaline (LC-NA) system. Reliable effects of taVNS on markers of LC-NA system activity, however, have not been demonstrated yet. Methods The aim of the present study was to overcome previous limitations by pooling raw data from a large sample of ten taVNS studies (371 healthy participants) that collected salivary alpha-amylase (sAA) as a potential marker of central NA release. Results While a meta-analytic approach using summary statistics did not yield any significant effects, linear mixed model analyses showed that afferent stimulation of the vagus nerve via taVNS increased sAA levels compared to sham stimulation (b = 0.16, SE = 0.05, p = 0.001). When considering potential confounders of sAA, we further replicated previous findings on the diurnal trajectory of sAA activity. Conclusion(s) Vagal activation via taVNS increases sAA release compared to sham stimulation, which likely substantiates the assumption that taVNS triggers NA release. Moreover, our results highlight the benefits of data pooling and data sharing in order to allow stronger conclusions in research. KW - Non-invasive vagus nerve stimulation KW - tVNS KW - sAA KW - Noradrenaline KW - Biomarker KW - Data pooling Y1 - 2022 U6 - https://doi.org/10.1016/j.brs.2022.09.009 SN - 1876-4754 VL - 15 SP - 1378 EP - 1388 PB - Elsevier CY - New York, NY, USA ET - 6 ER - TY - JOUR A1 - Sommer, C. A1 - Garbusow, Maria A1 - Juenger, E. A1 - Pooseh, S. A1 - Bernhardt, Nadine A1 - Birkenstock, J. A1 - Schad, Daniel A1 - Jabs, B. A1 - Gloeckler, T. A1 - Huys, Quentin J. M. A1 - Heinz, A. A1 - Smolka, Michael N. A1 - Zimmermann, Ulrich S. T1 - Strong seduction: impulsivity and the impact of contextual cues on instrumental behavior in alcohol dependence JF - Translational Psychiatry N2 - Alcohol-related cues acquire incentive salience through Pavlovian conditioning and then can markedly affect instrumental behavior of alcohol-dependent patients to promote relapse. However, it is unclear whether similar effects occur with alcohol-unrelated cues. We tested 116 early-abstinent alcohol-dependent patients and 91 healthy controls who completed a delay discounting task to assess choice impulsivity, and a Pavlovian-to-instrumental transfer (PIT) paradigm employing both alcohol-unrelated and alcohol-related stimuli. To modify instrumental choice behavior, we tiled the background of the computer screen either with conditioned stimuli (CS) previously generated by pairing abstract pictures with pictures indicating monetary gains or losses, or with pictures displaying alcohol or water beverages. CS paired to money gains and losses affected instrumental choices differently. This PIT effect was significantly more pronounced in patients compared to controls, and the group difference was mainly driven by highly impulsive patients. The PIT effect was particularly strong in trials in which the instrumental stimulus required inhibition of instrumental response behavior and the background CS was associated to monetary gains. Under that condition, patients performed inappropriate approach behavior, contrary to their previously formed behavioral intention. Surprisingly, the effect of alcohol and water pictures as background stimuli resembled that of aversive and appetitive CS, respectively. These findings suggest that positively valenced background CS can provoke dysfunctional instrumental approach behavior in impulsive alcohol-dependent patients. Consequently, in real life they might be easily seduced by environmental cues to engage in actions thwarting their long-term goals. Such behaviors may include, but are not limited to, approaching alcohol. Y1 - 2017 U6 - https://doi.org/10.1038/tp.2017.158 SN - 2158-3188 VL - 7 SP - 1209 EP - 1222 PB - Nature Publ. Group CY - New York ER - TY - JOUR A1 - Küken, Anika A1 - Sommer, Frederik A1 - Yaneva-Roder, Liliya A1 - Mackinder, Luke C. M. A1 - Hoehne, Melanie A1 - Geimer, Stefan A1 - Jonikas, Martin C. A1 - Schroda, Michael A1 - Stitt, Mark A1 - Nikoloski, Zoran A1 - Mettler-Altmann, Tabea T1 - Effects of microcompartmentation on flux distribution and metabolic pools in Chlamydomonas reinhardtii chloroplasts JF - eLife N2 - Cells and organelles are not homogeneous but include microcompartments that alter the spatiotemporal characteristics of cellular processes. The effects of microcompartmentation on metabolic pathways are however difficult to study experimentally. The pyrenoid is a microcompartment that is essential for a carbon concentrating mechanism (CCM) that improves the photosynthetic performance of eukaryotic algae. Using Chlamydomonas reinhardtii, we obtained experimental data on photosynthesis, metabolites, and proteins in CCM-induced and CCM-suppressed cells. We then employed a computational strategy to estimate how fluxes through the Calvin-Benson cycle are compartmented between the pyrenoid and the stroma. Our model predicts that ribulose-1,5-bisphosphate (RuBP), the substrate of Rubisco, and 3-phosphoglycerate (3PGA), its product, diffuse in and out of the pyrenoid, respectively, with higher fluxes in CCM-induced cells. It also indicates that there is no major diffusional barrier to metabolic flux between the pyrenoid and stroma. Our computational approach represents a stepping stone to understanding microcompartmentalized CCM in other organisms. Y1 - 2018 U6 - https://doi.org/10.7554/eLife.37960 SN - 2050-084X VL - 7 PB - eLife Sciences Publications CY - Cambridge ER - TY - JOUR A1 - Sebold, Miriam Hannah A1 - Nebe, Stephan A1 - Garbusow, Maria A1 - Guggenmos, Matthias A1 - Schad, Daniel A1 - Beck, Anne A1 - Kuitunen-Paul, Sören A1 - Sommer, Christian A1 - Frank, Robin A1 - Neu, Peter A1 - Zimmermann, Ulrich S. A1 - Rapp, Michael Armin A1 - Smolka, Michael N. A1 - Huys, Quentin J. M. A1 - Schlagenhauf, Florian A1 - Heinz, Andreas T1 - When Habits Are Dangerous: Alcohol Expectancies and Habitual Decision Making Predict Relapse in Alcohol Dependence JF - Biological psychiatry : a journal of psychiatric neuroscience and therapeutics ; a publication of the Society of Biological Psychiatry N2 - BACKGROUND: Addiction is supposedly characterized by a shift from goal-directed to habitual decision making, thus facilitating automatic drug intake. The two-step task allows distinguishing between these mechanisms by computationally modeling goal-directed and habitual behavior as model-based and model-free control. In addicted patients, decision making may also strongly depend upon drug-associated expectations. Therefore, we investigated model-based versus model-free decision making and its neural correlates as well as alcohol expectancies in alcohol-dependent patients and healthy controls and assessed treatment outcome in patients. METHODS: Ninety detoxified, medication-free, alcohol-dependent patients and 96 age-and gender-matched control subjects underwent functional magnetic resonance imaging during the two-step task. Alcohol expectancies were measured with the Alcohol Expectancy Questionnaire. Over a follow-up period of 48 weeks, 37 patients remained abstinent and 53 patients relapsed as indicated by the Alcohol Timeline Followback method. RESULTS: Patients who relapsed displayed reduced medial prefrontal cortex activation during model-based decision making. Furthermore, high alcohol expectancies were associated with low model-based control in relapsers, while the opposite was observed in abstainers and healthy control subjects. However, reduced model-based control per se was not associated with subsequent relapse. CONCLUSIONS: These findings suggest that poor treatment outcome in alcohol dependence does not simply result from a shift from model-based to model-free control but is instead dependent on the interaction between high drug expectancies and low model-based decision making. Reduced model-based medial prefrontal cortex signatures in those who relapse point to a neural correlate of relapse risk. These observations suggest that therapeutic interventions should target subjective alcohol expectancies. KW - Alcohol dependence KW - Alcohol expectancy KW - Goal-directed control KW - Medial prefrontal cortex KW - Reinforcement learning KW - Treatment outcome Y1 - 2017 U6 - https://doi.org/10.1016/j.biopsych.2017.04.019 SN - 0006-3223 SN - 1873-2402 VL - 82 SP - 847 EP - 856 PB - Elsevier CY - New York ER - TY - JOUR A1 - Schad, Daniel A1 - Garbusow, Maria A1 - Friedel, Eva A1 - Sommer, Christian A1 - Sebold, Miriam Hannah A1 - Hägele, Claudia A1 - Bernhardt, Nadine A1 - Nebe, Stephan A1 - Kuitunen-Paul, Sören A1 - Liu, Shuyan A1 - Eichmann, Uta A1 - Beck, Anne A1 - Wittchen, Hans-Ulrich A1 - Walter, Henrik A1 - Sterzer, Philipp A1 - Zimmermann, Ulrich S. A1 - Smolka, Michael N. A1 - Schlagenhauf, Florian A1 - Huys, Quentin J. M. A1 - Heinz, Andreas A1 - Rapp, Michael Armin T1 - Neural correlates of instrumental responding in the context of alcohol-related cues index disorder severity and relapse risk JF - European archives of psychiatry and clinical neuroscience : official organ of the German Society for Biological Psychiatry N2 - The influence of Pavlovian conditioned stimuli on ongoing behavior may contribute to explaining how alcohol cues stimulate drug seeking and intake. Using a Pavlovian-instrumental transfer task, we investigated the effects of alcohol-related cues on approach behavior (i.e., instrumental response behavior) and its neural correlates, and related both to the relapse after detoxification in alcohol-dependent patients. Thirty-one recently detoxified alcohol-dependent patients and 24 healthy controls underwent instrumental training, where approach or non-approach towards initially neutral stimuli was reinforced by monetary incentives. Approach behavior was tested during extinction with either alcohol-related or neutral stimuli (as Pavlovian cues) presented in the background during functional magnetic resonance imaging (fMRI). Patients were subsequently followed up for 6 months. We observed that alcohol-related background stimuli inhibited the approach behavior in detoxified alcohol-dependent patients (t = -3.86, p < .001), but not in healthy controls (t = -0.92, p = .36). This behavioral inhibition was associated with neural activation in the nucleus accumbens (NAcc) (t((30)) = 2.06, p < .05). Interestingly, both the effects were only present in subsequent abstainers, but not relapsers and in those with mild but not severe dependence. Our data show that alcohol-related cues can acquire inhibitory behavioral features typical of aversive stimuli despite being accompanied by a stronger NAcc activation, suggesting salience attribution. The fact that these findings are restricted to abstinence and milder illness suggests that they may be potential resilience factors. KW - Alcohol dependence KW - Human neuroimaging KW - Nucleus accumbens KW - Pavlovian-instrumental transfer KW - Relapse Y1 - 2018 U6 - https://doi.org/10.1007/s00406-017-0860-4 SN - 0940-1334 SN - 1433-8491 VL - 269 IS - 3 SP - 295 EP - 308 PB - Springer CY - Heidelberg ER - TY - GEN A1 - Garbusow, Maria A1 - Sommer, C. A1 - Nebe, S. A1 - Sebold, Miriam Hannah A1 - Kuitunen-Paul, Sören A1 - Wittchen, H. U. A1 - Smolka, M. A1 - Zimmermann, U. A1 - Rapp, Michael Armin A1 - Huys, Q. A1 - Schlagenhauf, Florian A1 - Heinz, A. T1 - Pavlovian-instrumental transfer in the course of alcohol use disorder T2 - European psychiatry : the journal of the Association of European Psychiatrists N2 - Background: Pavlovian processes are thought to play an important role in the development, maintenance and relapse of alcohol dependence, possibly by influencing and usurping on- going thought and behavior. The influence of Pavlovian stimuli on on-going behavior is paradigmatically measured by Pavlovian-to-instrumental-transfer (PIT) tasks. These involve multiple stages and are complex. Whether increased PIT is involved in human alcohol dependence is uncertain. We therefore aimed to establish and validate a modified PIT paradigm that would be robust, consistent, and tolerated by healthy controls as well as by patients suffering from alcohol dependence, and to explore whether alcohol dependence is associated with enhanced Pavlovian-Instrumental transfer. Methods: 32 recently detoxified alcohol-dependent patients and 32 age and gender matched healthy controls performed a PIT task with instrumental go/no-go approach behaviours. The task involved both Pavlovian stimuli associated with monetary rewards and losses, and images of drinks. Results: Both patients and healthy controls showed a robust and temporally stable PIT effect. Strengths of PIT effects to drug-related and monetary conditioned stimuli were highly correlated. Patients more frequently showed a PIT effect and the effect was stronger in response to aversively conditioned CSs (conditioned suppression), but there was no group difference in response to appetitive CSs. Conclusion: The implementation of PIT has favorably robust properties in chronic alcohol- dependent patients and in healthy controls. It shows internal consistency between monetary and drug-related cues. The findings support an association of alcohol dependence with an increased propensity towards PIT. Y1 - 2018 SN - 0924-9338 SN - 1778-3585 VL - 48 SP - S546 EP - S546 PB - Elsevier CY - ISSY-LES-MOULINEAUX ER - TY - JOUR A1 - Garbusow, Maria A1 - Schad, Daniel A1 - Sommer, Christian A1 - Juenger, Elisabeth A1 - Sebold, Miriam Hannah A1 - Friedel, Eva A1 - Wendt, Jean A1 - Kathmann, Norbert A1 - Schlagenhauf, Florian A1 - Zimmermann, Ulrich S. A1 - Heinz, Andreas A1 - Huys, Quentin J. M. A1 - Rapp, Michael Armin T1 - Pavlovian-to-instrumental transfer in alcohol dependence: a pilot study JF - Neuropsychobiology : international journal of experimental and clinical research in biological psychiatry, pharmacopsychiatry, Biological Psychology/Pharmacopsychology and Pharmacoelectroencephalography N2 - Background: Pavlovian processes are thought to play an important role in the development, maintenance and relapse of alcohol dependence, possibly by influencing and usurping ongoing thought and behavior. The influence of pavlovian stimuli on ongoing behavior is paradigmatically measured by pavlovian-to-instrumental transfer (PIT) tasks. These involve multiple stages and are complex. Whether increased PIT is involved in human alcohol dependence is uncertain. We therefore aimed to establish and validate a modified PIT paradigm that would be robust, consistent and tolerated by healthy controls as well as by patients suffering from alcohol dependence, and to explore whether alcohol dependence is associated with enhanced PIT. Methods: Thirty-two recently detoxified alcohol-dependent patients and 32 age- and gender-matched healthy controls performed a PIT task with instrumental go/no-go approach behaviors. The task involved both pavlovian stimuli associated with monetary rewards and losses, and images of drinks. Results: Both patients and healthy controls showed a robust and temporally stable PIT effect. Strengths of PIT effects to drug-related and monetary conditioned stimuli were highly correlated. Patients more frequently showed a PIT effect, and the effect was stronger in response to aversively conditioned CSs (conditioned suppression), but there was no group difference in response to appetitive CSs. Conclusion: The implementation of PIT has favorably robust properties in chronic alcohol-dependent patients and in healthy controls. It shows internal consistency between monetary and drug-related cues. The findings support an association of alcohol dependence with an increased propensity towards PIT. KW - Pavlovian-to-instrumental transfer KW - Alcohol dependence KW - Human Y1 - 2014 U6 - https://doi.org/10.1159/000363507 SN - 0302-282X SN - 1423-0224 VL - 70 IS - 2 SP - 111 EP - 121 PB - Karger CY - Basel ER - TY - GEN A1 - Sebold, Miriam Hannah A1 - Nebe, Stephan A1 - Garbusow, Maria A1 - Schad, Daniel A1 - Sommer, Christian A1 - Rapp, Michael Armin A1 - Smolka, Michael N. A1 - Huys, Quentin J. M. A1 - Schlagenhauf, Florian A1 - Heinz, Andreas T1 - Neurobiological correlates of learning and decision-making in alcohol dependence T2 - European psychiatry : the journal of the Association of European Psychiatrists Y1 - 2017 U6 - https://doi.org/10.1016/j.eurpsy.2017.01.084 SN - 0924-9338 SN - 1778-3585 VL - 41 SP - S11 EP - S11 PB - Elsevier CY - Paris ER - TY - JOUR A1 - Dimigen, Olaf A1 - Sommer, Werner A1 - Hohlfeld, Annette A1 - Jacobs, Arthur M. A1 - Kliegl, Reinhold T1 - Coregistration of eye movements and EEG in natural reading analyses and review JF - Journal of experimental psychology : General N2 - Brain-electric correlates of reading have traditionally been studied with word-by-word presentation, a condition that eliminates important aspects of the normal reading process and precludes direct comparisons between neural activity and oculomotor behavior. In the present study, we investigated effects of word predictability on eye movements (EM) and fixation-related brain potentials (FRPs) during natural sentence reading. Electroencephalogram (EEG) and EM (via video-based eye tracking) were recorded simultaneously while subjects read heterogeneous German sentences, moving their eyes freely over the text. FRPs were time-locked to first-pass reading fixations and analyzed according to the cloze probability of the currently fixated word. We replicated robust effects of word predictability on EMs and the N400 component in FRPs. The data were then used to model the relation among fixation duration, gaze duration, and N400 amplitude, and to trace the time course of EEG effects relative to effects in EM behavior. In an extended Methodological Discussion section, we review 4 technical and data-analytical problems that need to be addressed when FRPs are recorded in free-viewing situations (such as reading, visual search, or scene perception) and propose solutions. Results suggest that EEG recordings during normal vision are feasible and useful to consolidate findings from EEG and eye-tracking studies. KW - EEG KW - eye tracking KW - fixation-related potentials KW - artifact correction KW - natural viewing Y1 - 2011 U6 - https://doi.org/10.1037/a0023885 SN - 0096-3445 VL - 140 IS - 4 SP - 552 EP - 572 PB - American Psychological Association CY - Washington ER - TY - GEN A1 - Garbusow, Maria A1 - Sommer, Christian A1 - Nebe, Stephan A1 - Sebold, Miriam Hannah A1 - Kuitunen-Paul, Sören A1 - Wittchen, Hans-Ulrich A1 - Smolka, Michael N. A1 - Zimmermann, Ulrich S. A1 - Rapp, Michael Armin A1 - Huys, Quentin J. M. A1 - Schlagenhauf, Florian A1 - Heinz, Andreas T1 - Multi-level evidence of general pavlovian-to-instrumental transfer in alcohol use disorder T2 - Alcoholism : clinical and experimental research ; the official journal of the American Medical Society on Alcoholism and the Research Society on Alcoholism Y1 - 2018 SN - 0145-6008 SN - 1530-0277 VL - 42 SP - 128A EP - 128A PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Kliegl, Reinhold A1 - Dambacher, Michael A1 - Dimigen, Olaf A1 - Jacobs, Arthur M. A1 - Sommer, Werner T1 - Eye movements and brain electric potentials during reading JF - Psychological research : an international journal of perception, attention, memory, and action N2 - The development of theories and computational models of reading requires an understanding of processing constraints, in particular of timelines related to word recognition and oculomotor control. Timelines of word recognition are usually determined with event-related potentials (ERPs) recorded under conditions of serial visual presentation (SVP) of words; timelines of oculomotor control are derived from parameters of eye movements (EMs) during natural reading. We describe two strategies to integrate these approaches. One is to collect ERPs and EMs in separate SVP and natural reading experiments for the same experimental material (but different subjects). The other strategy is to co-register EMs and ERPs during natural reading from the same subjects. Both strategies yield data that allow us to determine how lexical properties influence ERPs (e.g., the N400 component) and EMs (e.g., fixation durations) across neighboring words. We review our recent research on the effects of frequency and predictability of words on both EM and ERP measures with reference to current models of eye-movement control during reading. Results are in support of the proposition that lexical access is distributed across several fixations and across brain-electric potentials measured on neighboring words. Y1 - 2012 U6 - https://doi.org/10.1007/s00426-011-0376-x SN - 0340-0727 VL - 76 IS - 2 SP - 145 EP - 158 PB - Springer CY - Heidelberg ER - TY - GEN A1 - Küken, Anika A1 - Sommer, Frederik A1 - Yaneva-Roder, Liliya A1 - Mackinder, Luke C.M. A1 - Höhne, Melanie A1 - Geimer, Stefan A1 - Jonikas, Martin C. A1 - Schroda, Michael A1 - Stitt, Mark A1 - Nikoloski, Zoran A1 - Mettler-Altmann, Tabea T1 - Effects of microcompartmentation on flux distribution and metabolic pools in Chlamydomonas reinhardtii chloroplasts T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - Cells and organelles are not homogeneous but include microcompartments that alter the spatiotemporal characteristics of cellular processes. The effects of microcompartmentation on metabolic pathways are however difficult to study experimentally. The pyrenoid is a microcompartment that is essential for a carbon concentrating mechanism (CCM) that improves the photosynthetic performance of eukaryotic algae. Using Chlamydomonas reinhardtii, we obtained experimental data on photosynthesis, metabolites, and proteins in CCM-induced and CCM-suppressed cells. We then employed a computational strategy to estimate how fluxes through the Calvin-Benson cycle are compartmented between the pyrenoid and the stroma. Our model predicts that ribulose-1,5-bisphosphate (RuBP), the substrate of Rubisco, and 3-phosphoglycerate (3PGA), its product, diffuse in and out of the pyrenoid, respectively, with higher fluxes in CCM-induced cells. It also indicates that there is no major diffusional barrier to metabolic flux between the pyrenoid and stroma. Our computational approach represents a stepping stone to understanding microcompartmentalized CCM in other organisms. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1122 KW - carbon concentrating mechanism KW - B12-dependent 1,2-propanediol degradation KW - green algae KW - co2 concentrating mechanism KW - salmonella typhimurium KW - co2 concentration KW - enzyme activities KW - anhydrase CAH3 KW - protein KW - expression Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-446358 SN - 1866-8372 IS - 1122 ER -