International Max Planck Research School

München, Germany

International Max Planck Research School

München, Germany
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Sauerhofer E.,11 Health | Pamplona F.A.,Max Planck Institute of Psychiatry | Bedenk B.,Max Planck Institute of Psychiatry | Moll G.H.,11 Health | And 6 more authors.
Behavioural Brain Research | Year: 2012

Posttraumatic stress disorder (PTSD) is characterized by the presence of three major symptom clusters: persistent fear memories, hyperarousal, and avoidance. With a passage of time after the trauma, PTSD patients show an increase in unspecific fear and avoidance, a phenomenon termed " fear generalization" It is not clear whether fear generalization arises from the time-dependent growth of hyperarousal or changes in associative fear. The present study investigated behavioral and neuroanatomical correlates of non-associative and associative fear memory one week vs. one month after a trauma in a mouse model of PTSD with immediate vs. delayed foot shock application. The immediate shock procedure led to a lower contextual fear, but did not influence the hyperarousal (i.e. increased acoustic startle responses) assessed within the first week after the trauma. Only delayed shocked mice demonstrated generalization of contextual fear and an increase in generalized avoidance behavior, with no changes in hyperarousal one month after trauma. We observed the same increase in c-Fos expression following delayed and immediate shock presentation within the lateral, basolateral, central amygdala and CA1, CA3 and dentate gyrus of hippocampus, suggesting that all of these structures contribute to the development of hyperarousal. Only basolateral amygdala and dentate gyrus appeared to be additionally involved in encoding of contextual information. In summary, our results demonstrate the independence of associative and non-associative trauma-related fear. They support the hypothesis that generalized fear emerges in consequence of forgetting specific stimulus attributes associated with the shock context. © 2012 Elsevier B.V.

Premoli I.,University of Tübingen | Premoli I.,International Max Planck Research School | Rivolta D.,University of East London | Espenhahn S.,University of Tübingen | And 4 more authors.
NeuroImage | Year: 2014

GABAB-receptor (GABABR) mediated inhibition is important in regulating neuronal excitability. The paired-pulse transcranial magnetic stimulation (TMS) protocol of long-interval intracortical inhibition (LICI) likely reflects this GABABergic inhibition. However, this view is based on indirect evidence from electromyographic (EMG) studies. Here we combined paired-pulse TMS with simultaneous electroencephalography (paired-pulse TMS-EEG) and pharmacology to directly investigate mechanisms of LICI at the cortical level. We tested the effects of a conditioning stimulus (CS100) applied 100ms prior to a test stimulus (TS) over primary motor cortex on TS-evoked EEG-potentials (TEPs). Healthy subjects were given a single oral dose of baclofen, a GABABR agonist, or diazepam, a positive modulator at GABAARs, in a placebo-controlled, pseudo-randomized double-blinded crossover study. LICI was quantified as the difference between paired-pulse TEPs (corrected for long-lasting EEG responses by the conditioning pulse) minus single-pulse TEPs. LICI at baseline (i.e. pre-drug intake) was characterized by decreased P25, N45, N100 and P180 and increased P70 TEP components. Baclofen resulted in a trend towards the enhancement of LICI of the N45 and N100, and significantly enhanced LICI of the P180. In contrast, diazepam consistently suppressed LICI of late potentials (i.e. N100, P180), without having an effect on LICI of earlier (i.e. P25, N45 and P70) potentials. These findings demonstrate for the first time directly at the system level of the human cortex that GABABR-mediated cortical inhibition contributes to LICI, while GABAAR-mediated inhibition occludes LICI. Paired-pulse TMS-EEG allows investigating cortical GABABR-mediated inhibition more directly and specifically than hitherto possible, and may thus inform on network abnormalities caused by disordered inhibition, e.g. in patients with schizophrenia or epilepsy. © 2014 Elsevier Inc.

Zander T.,University of Tübingen | Zander T.,International Max Planck Research School | Zander T.,University of Basel | Horr N.K.,University of Tübingen | And 3 more authors.
Brain and Behavior | Year: 2016

Introduction: Intuition has been defined as the instantaneous, experience-based impression of coherence elicited by cues in the environment. In a context of discovery, intuitive decision-making processes can be conceptualized as occurring within two stages, the first of which comprises an implicit perception of coherence that is not (yet) verbalizable. Through a process of spreading activation, this initially non-conscious perception gradually crosses over a threshold of awareness and thereby becomes explicable. Because of its experiential basis, intuition shares conceptual similarities with implicit memory processes. Based on these, the study addresses two research questions: (1) Is the gradual nature of intuitive processes reflected on a neural level? (2) Do intuition-based decisions differ neurally from priming-based decisions? Methods: To answer these questions, we conducted an fMRI study using the triads task and presented participants with coherent word triads that converge on a common fourth concept, and incoherent word triads that do not converge on a common fourth concept. Participants had to perform semantic coherence judgments as well as to indicate whether they immediately knew the fourth concept. To enable investigating intuition-based and priming-based decisions within the same task and with the same participants, we implemented a conceptual priming procedure into the coherence judgment task. We realized this by priming participants with concepts associated with incoherent triads in separate priming blocks prior to the coherence judgments. Results: For intuition-based decisions, imaging results mainly revealed activity within the orbitofrontal cortex, within the inferior frontal gyrus and the middle temporal gyrus. Activity suppression in the right temporo-occipital complex was observed for priming-based decisions. Conclusions: With respect to research question 1, our data support a continuity model of intuition because the two intuitive stages show quantitatively distinct brain activation patterns. Regarding research question 2, we can draw the preliminary conclusion of a qualitative difference between intuition-based and priming-based decisions. The present results are first to demonstrate that an intuitive apprehension of semantic relations proceeds gradually. We were able to provide neuronal evidence for the two-stage model of intuition (cf. Bowers et al. 1990) and to further corroborate the role of the orbito-frontal cortex in intuitive processing. © 2016 Published by Wiley Periodicals, Inc.

Ruiz S.,University of Tübingen | Ruiz S.,Bernardo O'Higgins University | Buyukturkoglu K.,University of Tübingen | Buyukturkoglu K.,International Max Planck Research School | And 7 more authors.
Biological Psychology | Year: 2014

With the advent of brain computer interfaces based on real-time fMRI (rtfMRI-BCI), the possibility of performing neurofeedback based on brain hemodynamics has become a reality. In the early stage of the development of this field, studies have focused on the volitional control of activity in circumscribed brain regions. However, based on the understanding that the brain functions by coordinated activity of spatially distributed regions, there have recently been further developments to incorporate real-time feedback of functional connectivity and spatio-temporal patterns of brain activity. The present article reviews the principles of rtfMRI neurofeedback, its applications, benefits and limitations. A special emphasis is given to the discussion of novel developments that have enabled the use of this methodology to achieve self-regulation of the functional connectivity between different brain areas and of distributed brain networks, anticipating new and exciting applications for cognitive neuroscience and for the potential alleviation of neuropsychiatric disorders. © 2013 Elsevier B.V.

Premoli I.,University of Tübingen | Premoli I.,International Max Planck Research School | Castellanos N.,Technical University of Madrid | Rivolta D.,University of East London | And 10 more authors.
Journal of Neuroscience | Year: 2014

Combining transcranial magnetic stimulation (TMS) and electroencephalography (EEG) constitutes a powerful tool to directly assess human cortical excitability and connectivity. TMS of the primary motor cortex elicits a sequence of TMS-evoked EEG potentials (TEPs). It is thought that inhibitory neurotransmission through GABA-A receptors (GABAAR) modulates early TEPs (<50 ms after TMS), whereas GABA-B receptors (GABABR) play a role for later TEPs (at ~100 ms after TMS). However, the physiological underpinnings of TEPs have not been clearly elucidated yet. Here, we studied the role of GABAA/B-ergic neurotransmission for TEPs in healthy subjects using a pharmaco-TMS-EEG approach. In Experiment 1, we tested the effects of a single oral dose of alprazolam (a classical benzodiazepine acting as allosteric-positive modulator at α1, α2, α3, and α5 subunit-containing GABAARs) and zolpidem (a positive modulator mainly at the ÷1 GABAAR) in a double-blind, placebo-controlled, crossover study. In Experiment 2, we tested the influence of baclofen (a GABABR agonist) and diazepam (a classical benzodiazepine) versus placebo on TEPs. Alprazolam and diazepam increased the amplitude of the negative potential at 45 ms after stimulation (N45) and decreased the negative component at 100 ms (N100), whereas zolpidem increased the N45 only. In contrast, baclofen specifically increased the N100 amplitude. These results provide strong evidence that the N45 represents activity of ÷1-subunit-containing GABAARs, whereas the N100 represents activity of GABABRs. Findings open a novel window of opportunity to study alteration of GABAA-/GABAB-related inhibition in disorders, such as epilepsy or schizophrenia. © 2014 the authors.

Dallmeyer A.,Max Planck Institute for Meteorology | Claussen M.,Max Planck Institute for Meteorology | Claussen M.,University of Hamburg | Otto J.,International Max Planck Research School
Climate of the Past | Year: 2010

The impact of vegetation-atmosphere and ocean-atmosphere interactions on the mid- to late Holocene climate change as well as their synergy is studied for different parts of the Asian monsoon region, giving consideration to the large climatic and topographical heterogeneity in that area. We concentrate on temperature and precipitation changes as the main parameters describing monsoonal influenced climates. For our purpose, we analyse a set of coupled numerical experiments, performed with the comprehensive Earth system model ECHAM5/JSBACH-MPIOM under present-day and mid-Holocene (6 k) orbital configurations (Otto et al., 2009b). The temperature change caused by the insolation forcing reveals an enhanced seasonal cycle, with a pronounced warming in summer (0.58 K) and autumn (1.29 K) and a cooling in the other seasons (spring: -1.32 K; winter: -0.97 K). Most of this change can be attributed to the direct response of the atmosphere, but the ocean, whose reaction has a lagged seasonal cycle (warming in autumn and winter, cooling in the other seasons), strongly modifies the signal. The simulated contribution of dynamic vegetation is small and most effective in winter, where it slightly warms the near-surface atmosphere (approx. 0.03 K). The temperature difference attributed to the synergy is on average positive, but also small. Concerning the precipitation, the most remarkable change is the postponement and enhancement of the Asian monsoon (0.46 mm/day in summer, 0.53 mm/day in autumn), mainly related to the direct atmospheric response. On regional average, the interactive ocean (ca. 0.18 mm/day) amplifies the direct effect, but tends to weaken the East Asian summer monsoon and strongly increases the Indian summer monsoon rainfall rate (0.68 mm/day). The influence of dynamic vegetation on precipitation is comparatively small (<0.04 mm/day). The synergy effect has no influence, on average. © Author(s) 2010.

Rimac A.,Max Planck Institute for Meteorology | Rimac A.,International Max Planck Research School | Von Storch J.-S.,Max Planck Institute for Meteorology | Eden C.,University of Hamburg | Haak H.,Max Planck Institute for Meteorology
Geophysical Research Letters | Year: 2013

The wind power input to near-inertial (NI) motions is studied using a global eddy-permitting ocean general circulation model. The model is forced by high- (1-hourly, at 0.35° resolution) and low-resolution (6-hourly, at 1.875° resolution) wind data. A change from low- to high-resolution forcing results in an increase in NI kinetic energy by a factor three and raises the wind-generated power input to NI motions from 0.3 TW to 1.1 TW. Time and space filtering of the wind fields yield less kinetic energy, with a larger drop from time filtering. This strong sensitivity to wind forcing points to a possible underestimation of the wind-generated energy available for deep ocean mixing in previous studies based on low-resolution winds. © 2013. American Geophysical Union. All Rights Reserved.

Gazi M.A.,International Center for Diarrheal Disease Research | Islam M.R.,International Max Planck Research School | Islam M.R.,University of Bordeaux Segalen | Kibria M.G.,International Center for Diarrheal Disease Research | Mahmud Z.,University of Dhaka
European Journal of Clinical Microbiology and Infectious Diseases | Year: 2015

The global control of tuberculosis remains a great challenge from the standpoint of diagnosis, detection of drug resistance, and treatment, because treatment can only be initiated when infection is detected, and is guided by the results of antimicrobial susceptibility testing. To a large extent, non-molecular, immunological, and other biochemical methods are refinements or modifications of conventional methods, with the primary goal of providing more rapid test results. In contrast, molecular methods use novel technologies to detect the presence of Mycobacterium tuberculosis complex and genes conferring drug resistance. As a group, molecular technologies offer the greatest potential for laboratories in resource-rich countries because they have the highest sensitivity and specificity. In resource-poor settings, continued development of affordable, sensitive, and specific diagnostic tools will be required, where the incidence of disease is highest. © 2015, Springer-Verlag Berlin Heidelberg.

Held M.,Free University of Berlin | Held M.,International Max Planck Research School | Metzner P.,University of Lugano | Metzner P.,Deutsche Forschungsgemeinschaft Research Center | And 4 more authors.
Biophysical Journal | Year: 2011

Protein-ligand interactions are essential for nearly all biological processes, and yet the biophysical mechanism that enables potential binding partners to associate before specific binding occurs remains poorly understood. Fundamental questions include which factors influence the formation of protein-ligand encounter complexes, and whether designated association pathways exist. To address these questions, we developed a computational approach to systematically analyze the complete ensemble of association pathways. Here, we use this approach to study the binding of a phosphate ion to the Escherichia coli phosphate-binding protein. Various mutants of the protein are considered, and their effects on binding freeenergy profiles, association rates, and association pathway distributions are quantified. The results reveal the existence of two anion attractors, i.e., regions that initially attract negatively charged particles and allow them to be efficiently screened for phosphate, which is subsequently specifically bound. Point mutations that affect the charge on these attractors modulate their attraction strength and speed up association to a factor of 10 of the diffusion limit, and thus change the association pathways of the phosphate ligand. It is demonstrated that a phosphate that prebinds to such an attractor neutralizes its attraction effect to the environment, making the simultaneous association of a second phosphate ion unlikely. This study suggests ways in which structural properties can be used to tune molecular association kinetics so as to optimize the efficiency of binding, and highlights the importance of kinetic properties. © 2011 by the Biophysical Society.

Schultze-Krumbholz A.,Free University of Berlin | Schultze-Krumbholz A.,International Max Planck Research School | Scheithauer H.,Free University of Berlin
International Journal of Developmental Sciences | Year: 2013

Examination of the longitudinal relationship between empathy, social-emotional problems and cyberbullying is still rare and the present study is one of very few. The present study assessed whether low scores of affective and cognitive empathy at wave 1 (t1) can predict involvement in cyberbullying five months later (t2). Furthermore, it was examined whether involvement in cyberbullying at t1 predicts psychopathological symptoms and social withdrawal at t2. Participants were 777th and 8th grade students from a control group of a pre-/posttest short-term longitudinal evaluation study of a general anti-bullying program (mean aget1 = 12.53 years, SD = 0.68; gendert1 = 54.5% boys, 45.5% girls). Separate quasi-poisson regression analyses were conducted and traditional bullying and victimization were included as control variables. Low scores of affective, but not cognitive, empathy predicted cyberbullying but not cybervictimization at t2. Neither cyberbullying nor cybervictimization predicted social withdrawal or psychopathological symptoms at t2 as assessed in this study. The research hypotheses were only partly supported, however, this study using short-term longitudinal data revealed evidence for the importance of (affective) empathy in cyberbullying perpetration. © 2013 - IOS Press and the authors.

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