@article{GramAlbertovaSchirmeretal.2022, author = {Gram, Maximilian and Albertova, P. and Schirmer, V. and Blaimer, M. and Gamer, M. and Herrmann, M. J. and Nordbeck, P. and Jakob, P. M.}, title = {Towards robust in vivo quantification of oscillating biomagnetic fields using Rotary Excitation based MRI}, series = {Scientific Reports}, volume = {12}, journal = {Scientific Reports}, number = {1}, doi = {10.1038/s41598-022-19275-5}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-300862}, year = {2022}, abstract = {Spin-lock based functional magnetic resonance imaging (fMRI) has the potential for direct spatially-resolved detection of neuronal activity and thus may represent an important step for basic research in neuroscience. In this work, the corresponding fundamental effect of Rotary EXcitation (REX) is investigated both in simulations as well as in phantom and in vivo experiments. An empirical law for predicting optimal spin-lock pulse durations for maximum magnetic field sensitivity was found. Experimental conditions were established that allow robust detection of ultra-weak magnetic field oscillations with simultaneous compensation of static field inhomogeneities. Furthermore, this work presents a novel concept for the emulation of brain activity utilizing the built-in MRI gradient system, which allows REX sequences to be validated in vivo under controlled and reproducible conditions. Via transmission of Rotary EXcitation (tREX), we successfully detected magnetic field oscillations in the lower nano-Tesla range in brain tissue. Moreover, tREX paves the way for the quantification of biomagnetic fields.}, language = {en} } @article{LischkeHerpertzBergeretal.2017, author = {Lischke, Alexander and Herpertz, Sabine C. and Berger, Christoph and Domes, Gregor and Gamer, Matthias}, title = {Divergent effects of oxytocin on (para-)limbic reactivity to emotional and neutral scenes in females with and without borderline personality disorder}, series = {Social Cognitive and Affective Neuroscience}, volume = {12}, journal = {Social Cognitive and Affective Neuroscience}, number = {11}, doi = {10.1093/scan/nsx107}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-173309}, pages = {1783-1792}, year = {2017}, abstract = {Borderline personality disorder (BPD) patients' hypersensitivity for emotionally relevant stimuli has been suggested be due to abnormal activity and connectivity in (para-)limbic and prefrontal brain regions during stimulus processing. The neuropeptide oxytocin has been shown to modulate activity and functional connectivity in these brain regions, thereby optimizing the processing of emotional and neutral stimuli. To investigate whether oxytocin would be capable of attenuating BPD patients' hypersensitivity for such stimuli, we recorded brain activity and gaze behavior during the processing of complex scenes in 51 females with and 48 without BPD after intranasal application of either oxytocin or placebo. We found divergent effects of oxytocin on BPD and healthy control (HC) participants' (para-)limbic reactivity to emotional and neutral scenes: Oxytocin decreased amygdala and insula reactivity in BPD participants but increased it in HC participants, indicating an oxytocin-induced normalization of amygdala and insula activity during scene processing. In addition, oxytocin normalized the abnormal coupling between amygdala activity and gaze behavior across all scenes in BPD participants. Overall, these findings suggest that oxytocin may be capable of attenuating BPD patients' hypersensitivity for complex scenes, irrespective of their valence.}, language = {en} } @article{BiehlMerzDresleretal.2016, author = {Biehl, Stefanie C. and Merz, Christian J. and Dresler, Thomas and Heupel, Julia and Reichert, Susanne and Jacob, Christian P. and Deckert, J{\"u}rgen and Herrmann, Martin J.}, title = {Increase or Decrease of fMRI Activity in Adult Attention Deficit/ Hyperactivity Disorder: Does It Depend on Task Difficulty?}, series = {International Journal of Neuropsychopharmacology}, volume = {19}, journal = {International Journal of Neuropsychopharmacology}, number = {10}, doi = {10.1093/ijnp/pyw049}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-147551}, pages = {pyw049}, year = {2016}, abstract = {Background: Attention deficit/hyperactivity disorder has been shown to affect working memory, and fMRI studies in children and adolescents with attention deficit/hyperactivity disorder report hypoactivation in task-related attentional networks. However, studies with adult attention deficit/hyperactivity disorder patients addressing this issue as well as the effects of clinically valid methylphenidate treatment are scarce. This study contributes to closing this gap. Methods: Thirty-five adult patients were randomized to 6 weeks of double-blind placebo or methylphenidate treatment. Patients completed an fMRI n-back working memory task both before and after the assigned treatment, and matched healthy controls were tested and compared to the untreated patients. Results: There were no whole-brain differences between any of the groups. However, when specified regions of interest were investigated, the patient group showed enhanced BOLD responses in dorsal and ventral areas before treatment. This increase was correlated with performance across all participants and with attention deficit/hyperactivity disorder symptoms in the patient group. Furthermore, we found an effect of treatment in the right superior frontal gyrus, with methylphenidate-treated patients exhibiting increased activation, which was absent in the placebo-treated patients. Conclusions: Our results indicate distinct activation differences between untreated adult attention deficit/hyperactivity disorder patients and matched healthy controls during a working memory task. These differences might reflect compensatory efforts by the patients, who are performing at the same level as the healthy controls. We furthermore found a positive effect of methylphenidate on the activation of a frontal region of interest. These observations contribute to a more thorough understanding of adult attention deficit/hyperactivity disorder and provide impulses for the evaluation of therapy-related changes.}, language = {en} } @phdthesis{Wiemer2015, author = {Wiemer, Julian}, title = {Maintaining factors of fear-relevant illusory correlations}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-116960}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2015}, abstract = {Biased cognitive processes are very likely involved in the maintenance of fears and anxiety. One of such cognitive processes is the perceived relationship between fear-relevant stimuli and aversive consequences. If this relationship is perceived although objective contingencies have been random, it is called an (a posteriori) illusory correlation. If this relationship is overestimated before objective contingencies are experienced, it is called an (a priori) expectancy bias. Previous investigations showed that fear-relevant illusory correlations exist, but very few is known about how and why this cognitive bias develops. In the present dissertation thesis, a model is proposed based on a review of the literature on fear-relevant illusory correlations. This model describes how psychological factors might have an influence on fear and illusory correlations. Several critical implications of the model were tested in four experiments. Experiment 1 tested the hypothesis that people do not only overestimate the proportion of aversive consequences (startle sounds) following emotionally negative stimuli (pictures of mutilations) relative to neutral stimuli (pictures of household objects), but also following highly arousing positive stimuli (pictures of erotic scenes), because arousal might be an important determinant of illusory correlations. The result was a significant expectancy bias for negative stimuli and a much smaller expectancy bias for positive stimuli. Unexpectedly, expectancy bias was restricted to women. An a posteriori illusory correlation was not found overall, but only in those participants who perceived the aversive consequences following negative stimuli as particularly aversive. Experiment 2 tested the same hypothesis as experiment 1 using a paradigm that evoked distinct basic emotions (pictures inducing fear, anger, disgust or happiness). Only negative emotions resulted in illusory correlations with aversive outcomes (startle sounds), especially the emotions of fear and disgust. As in experiment 1, the extent of these illusory correlations was correlated with the perceived aversiveness of aversive outcomes. Moreover, only women overestimated the proportion of aversive outcomes during pictures that evoked fear, anger or disgust. Experiment 3 used functional Magnetic Resonance Imaging (fMRI) to measure biased brain activity in female spider phobics during an illusory correlation paradigm. Both spider phobics and healthy controls expected more aversive outcomes (painful electrical shocks) following pictures of spiders than following neutral control stimuli (pictures of mushrooms). Spider phobics but not healthy controls overestimated the proportion of aversive outcomes following pictures of spiders in a trial-by-trial memory task. This a posteriori illusory correlation was correlated with enhanced shock aversiveness and activity in primary sensory-motor cortex in phobic participants. Moreover, spider phobics' brain activity in the left dorsolateral prefrontal cortex was elevated in response to spider images. This activity also predicted the extent of the illusory correlation, which supports the theory that executive and attentional resources play an important role in the maintenance of illusory correlations. Experiment 4 tested the hypothesis that the enhanced aversiveness of some outcomes would be sufficient to causally induce an illusory correlation. Neutral images (colored geometric figures) were paired with differently aversive outcomes (three startle sounds varying in intensity). Participants developed an illusory correlation between those images, which predicted the most aversive sound and this sound, which means that this association was overestimated relative to the other associations. The extent of the illusory correlation was positively correlated with participants' self-reported anxiety. The results imply that the previously found relationship between illusory correlations and outcome aversiveness might reflect a causal impact of outcome aversiveness or salience on illusory correlations. In sum, the conducted experiments indicate that illusory correlations between fear-relevant stimuli and aversive consequences might persist - among other factors - because of an enhanced aversiveness or salience of aversive consequences following feared stimuli. This assumption is based on correlational findings, a neural measure of outcome perception and a causal influence of outcome aversiveness on illusory correlations. Implications of these findings were integrated into a model of fear-relevant illusory correlations and potential implications are discussed. Future investigations should further elucidate the role of executive functions and gender effects. Moreover, the trial-by-trial assessment of illusory correlations is recommended to increase reliability of the concept. From a clinical perspective, the down-regulation of aversive experiences and the allocation of attention to non-aversive experiences might help to cure anxiety and cognitive bias.}, subject = {Verzerrte Kognition}, language = {en} } @article{ZellerMuellerGutberletetal.2013, author = {Zeller, Mario and M{\"u}ller, Alexander and Gutberlet, Marcel and Nichols, Thomas and Hahn, Dietbert and K{\"o}stler, Herbert and Bartsch, Andreas J.}, title = {Boosting BOLD fMRI by K-Space Density Weighted Echo Planar Imaging}, series = {PLoS ONE}, journal = {PLoS ONE}, doi = {10.1371/journal.pone.0074501}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-97233}, year = {2013}, abstract = {Functional magnetic resonance imaging (fMRI) has become a powerful and influential method to non-invasively study neuronal brain activity. For this purpose, the blood oxygenation level-dependent (BOLD) effect is most widely used. T2* weighted echo planar imaging (EPI) is BOLD sensitive and the prevailing fMRI acquisition technique. Here, we present an alternative to its standard Cartesian recordings, i.e. k-space density weighted EPI, which is expected to increase the signal-to-noise ratio in fMRI data. Based on in vitro and in vivo pilot measurements, we show that fMRI by k-space density weighted EPI is feasible and that this new acquisition technique in fact boosted spatial and temporal SNR as well as the detection of local fMRI activations. Spatial resolution, spatial response function and echo time were identical for density weighted and conventional Cartesian EPI. The signal-to-noise ratio gain of density weighting can improve activation detection and has the potential to further increase the sensitivity of fMRI investigations.}, language = {en} } @phdthesis{Dresler2011, author = {Dresler, Thomas}, title = {Die neuronale Verarbeitung emotionaler Reize bei Patienten mit Panikst{\"o}rung - eine Betrachtung der neuroanatomischen Hypothese}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-64932}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2011}, abstract = {Hintergrund: Die Panikst{\"o}rung ist eine die Lebensqualit{\"a}t beeintr{\"a}chtigende psychische St{\"o}rung, die unbehandelt einen chronischen Verlauf zeigt, jedoch sowohl durch Psychotherapie als auch Psychopharmakotherapie erfolgreich behandelt werden kann. Die der Panikst{\"o}rung zugrundeliegenden neuronalen Schaltkreise werden in der von Gorman et al. (1989, 2000) ver{\"o}ffentlichten neuroanatomischen Hypothese beschrieben. In der stark an der Tierforschung angelehnten revidierten Version (2000) wird die Amygdala als Zentrum eines komplexen Furchtnetzwerks angesehen, deren Aktivit{\"a}t durch h{\"o}here kortikale Areale im pr{\"a}frontalen Kortex moduliert wird. Trotz der Popularit{\"a}t der Hypothese sind deren Annahmen bislang kaum explizit {\"u}berpr{\"u}ft worden. Ziel: Ziel der Untersuchung war es, die neuronale Verarbeitung emotionaler Reize in empirischen Experimenten genauer zu untersuchen, da die Datenlage in diesem Bereich noch gering und inkonsistent ist und Replikationsstudien fehlen. Außerdem sollte ein {\"U}berblick {\"u}ber die bereits ver{\"o}ffentlichten empirischen Studien gegeben werden, welche mit bildgebenden Verfahren Aussagen {\"u}ber die Beteiligung bestimmter neuronaler Strukturen bei der Panikst{\"o}rung erlauben. Methoden: An den Standorten W{\"u}rzburg und Hamburg wurden Patienten mit Panikst{\"o}rung (n = 18/20) und gesunde Kontrollen (n = 27/23) mit zwei Paradigmen zur Verarbeitung emotionaler Reize (emotionaler Stroop-Test und Gesichterverarbeitung) mit der funktionellen Magnetresonanztomographie untersucht. Hierbei sollten insbesondere die in der neuroanatomischen Hypothese wichtigen Strukturen Amygdala und pr{\"a}frontaler Kortex betrachtet werden. Bildgebende Studien, die Patienten mit Panikst{\"o}rung untersuchten, wurden {\"u}ber eine Literaturrecherche ermittelt, in Untergruppen von Studien eingeteilt und bewertet. Ergebnisse: In beiden untersuchten Stichproben zeigten die Patienten im Vergleich zu den Kontrollen auf Reaktionszeitebene einen signifikanten emotionalen Stroop-Effekt mit verl{\"a}ngerten Antwortlatenzen f{\"u}r panikrelevante W{\"o}rter. In den funktionellen Daten zeigten sich keine Unterschiede in der Amygdalaaktivierung, jedoch zeigten die Patienten f{\"u}r den Kontrast ‚panikrelevante vs. neutrale W{\"o}rter' im Gruppenvergleich eine erh{\"o}hte Aktivierung in pr{\"a}frontalen Arealen. Bei der Verarbeitung emotionaler Gesichter gab es kaum Unterschiede zwischen den Gruppen, {\"a}ngstliche Gesichter l{\"o}sten im Vergleich zu neutralen Gesichtern keine erh{\"o}hte Amygdalaaktivierung aus. Hinweise auf eine generelle Hypofrontalit{\"a}t ließen sich bei den Patienten - zumindest bei der Verarbeitung emotionaler Reize - in den angewandten Paradigmen nicht finden. Schlussfolgerung: Die Ergebnisse der experimentellen Untersuchung und des Literatur{\"u}berblicks zeigen, dass - trotz durchaus mit der neuroanatomischen Hypothese in Einklang stehender Befunde - Inkonsistenzen zu finden sind, die mit der aktuellen Hypothese nicht erkl{\"a}rt werden k{\"o}nnen. Die Ergebnisse der vorliegenden Untersuchung im emotionalen Stroop-Test konnten bisher gefundene pr{\"a}frontale Aktivierungsmuster replizieren, f{\"u}r die Amygdala gilt das nicht. Eine Erweiterung der Hypothese durch die Ber{\"u}cksichtigung neuer Aspekte k{\"o}nnte helfen, diese Befunde besser zu erkl{\"a}ren und zu einem umfassenderen Bild der neuronalen Grundlagen der St{\"o}rung beitragen. Modifikationen werden vorgeschlagen, die der Weiterentwicklung der Hypothese dienen k{\"o}nnten und bei der Planung zuk{\"u}nftiger Studien ber{\"u}cksichtigt werden sollten. Die vermutete prominente Rolle der Amygdala bei der Panikst{\"o}rung ist nach wie vor nicht hinreichend untersucht und der modulierende Einfluss pr{\"a}frontaler Strukturen sollte zuk{\"u}nftig insbesondere im direkten Zusammenspiel mit der Amygdala, z. B. im Rahmen psychotherapeutischer Interventionen, genauer analysiert werden.}, subject = {Paniksyndrom}, language = {de} }