Johannes Schultz

Kinetics and Dose Dependency of Intranasal Oxytocin Effects on Amygdala Reactivity

BACKGROUND Current neuroimaging perspectives on a variety of mental disorders emphasize dysfunction of the amygdala. The neuropeptide oxytocin (OXT), a key mediator in the regulation of social cognition and behavior, accumulates in cerebrospinal fluid after intranasal administration in macaques and humans and modulates amygdala reactivity in both species. However, the translation of neuromodulatory OXT effects to novel treatment approaches is hampered by the absence of studies defining the most effective dose and dose-response latency for targeting the amygdala. METHODS To address this highly relevant issue, a total of 116 healthy men underwent functional magnetic resonance imaging using a randomized, double-blind, placebo-controlled crossover study design. The experimental rationale was to systematically vary dose-test latencies (15-40, 45-70, and 75-100 minutes) and doses of OXT (12, 24, and 48 international units) in order to identify the most robust effects on amygdala reactivity. During functional magnetic resonance imaging, subjects completed an emotional face recognition task including stimuli with varying intensities ranging from low (highly ambiguous) to high (less ambiguous). RESULTS Our results indicate that the OXT-induced inhibition of amygdala responses to fear was most effective in a time window between 45 and 70 minutes after administration of a dose of 24 international units. Furthermore, the observed effect was most evident in subjects scoring high on measures of autistic-like traits. Behavioral response patterns suggest that OXT specifically reduced an emotional bias in the perception of ambiguous faces. CONCLUSIONS These findings provide initial evidence of the most effective dose and dose-test interval for future experimental or therapeutic regimens aimed at targeting amygdala functioning using intranasal OXT administration.

General and emotion-specific neural effects of ketamine during emotional memory formation

Abstract Animal studies suggest that N‐methyl‐D‐aspartate receptor (NMDAR) dependent signalling in limbic and prefrontal regions is critically involved in both cognitive and emotional functions. In humans, ketamine‐induced transient, and disorder associated chronic NMDAR hypofunction (i.e. in schizophrenia) has been associated with deficient performance in the domains of memory and higher‐order emotional functioning, as well as altered neural activity in the underlying limbic‐prefrontal circuits. To model the effects of NMDAR hypofunction on the integration of emotion and cognition the present pharmacological fMRI study applied the NMDAR antagonist ketamine (target plasma level=100 ng/ml) to 21 healthy volunteers in a within‐subject placebo‐controlled crossover design during encoding of neutral, positive and negative pictures. Our results show that irrespective of emotion, ketamine suppressed parahippocampal and medial prefrontal activity. In contrast, ketamine selectively increased amygdala and orbitofrontal activity during successful encoding of negative stimuli. On the network level ketamine generally increased medial prefrontal‐parahippocampal coupling while specifically decreasing amygdala‐orbitofrontal interplay during encoding of negative stimuli. On the behavioural level, ketamine produced generally decreased memory performance and abolished the emotional enhancement of memory after a wash‐out period of 5 days. The present findings suggest that ketamine produces general as well as valence‐specific effects during emotional memory formation. The pattern partly overlaps with alterations previously observed in patients with schizophrenia. HighlightsKetamine suppresses parahippocampal and prefrontal activity during encoding.Amygdala and orbitofrontal activity is increased for negative stimuli by ketamine.Ketamine generally increases medial prefrontal‐parahippocampal coupling.The general and emotion‐specific effects overlap with alterations in schizophrenia.

The Sense of Agency Is More Sensitive to Manipulations of Outcome than Movement-Related Feedback Irrespective of Sensory Modality

The sense of agency describes the ability to experience oneself as the agent of ones own actions. Previous studies of the sense of agency manipulated the predicted sensory feedback related either to movement execution or to the movement’s outcome, for example by delaying the movement of a virtual hand or the onset of a tone that resulted from a button press. Such temporal sensorimotor discrepancies reduce the sense of agency. It remains unclear whether movement-related feedback is processed differently than outcome-related feedback in terms of agency experience, especially if these types of feedback differ with respect to sensory modality. We employed a mixed-reality setup, in which participants tracked their finger movements by means of a virtual hand. They performed a single tap, which elicited a sound. The temporal contingency between the participants’ finger movements and (i) the movement of the virtual hand or (ii) the expected auditory outcome was systematically varied. In a visual control experiment, the tap elicited a visual outcome. For each feedback type and participant, changes in the sense of agency were quantified using a forced-choice paradigm and the Method of Constant Stimuli. Participants were more sensitive to delays of outcome than to delays of movement execution. This effect was very similar for visual or auditory outcome delays. Our results indicate different contributions of movement- versus outcome-related sensory feedback to the sense of agency, irrespective of the modality of the outcome. We propose that this differential sensitivity reflects the behavioral importance of assessing authorship of the outcome of an action.

Sensitivity of proxies on non-linear interactions in the climate system.

Recent climate change is affecting the earth system to an unprecedented extent and intensity and has the potential to cause severe ecological and socioeconomic consequences. To understand natural and anthropogenic induced processes, feedbacks, trends, and dynamics in the climate system, it is also essential to consider longer timescales. In this context, annually resolved tree-ring data are often used to reconstruct past temperature or precipitation variability as well as atmospheric or oceanic indices such as the North Atlantic Oscillation (NAO) or the Atlantic Multidecadal Oscillation (AMO). The aim of this study is to assess weather-type sensitivity across the Northern Atlantic region based on two tree-ring width networks. Our results indicate that nonstationarities in superordinate space and time scales of the climate system (here synoptic- to global scale, NAO, AMO) can affect the climate sensitivity of tree-rings in subordinate levels of the system (here meso- to synoptic scale, weather-types). This scale bias effect has the capability to impact even large multiproxy networks and the ability of these networks to provide information about past climate conditions. To avoid scale biases in climate reconstructions, interdependencies between the different scales in the climate system must be considered, especially internal ocean/atmosphere dynamics.

Evaluation of Tree Growth Relevant Atmospheric Circulation Patterns for Geopotential Height Field Reconstructions for Asia

AbstractAtmospheric circulations influence local and regional weather conditions and, thus, tree growth. To identify summer weather types relevant for tree growth, and their associated synoptic-sca...

Technical note: using ISS videos in Earth observation – implementations for science and education

ABSTRACT A large variety of various passive and active satellite sensors producing panchromatic, multispectral or hyperspectral images of the Earth’s surface are currently in space and are used in different scientific fields such as earth science (e.g. geography, hydrology, geology, oceanography and glaciology), disaster management, as well as for military, commercial and economic purposes. In contrast, video files are a rather exotic data format in the field of Earth observation. Occasionally, video cameras are used in airborne remote sensing, but only recently video Earth observation from space has been established. This paper aims at the integration of video data in the scientific workflow, revealing advantages and disadvantages of moving images. Being the only available source for continuous video Earth observation data, the NASA experiment High Definition Earth Viewing on-board the International Space Station is the basis for our evaluation of the usability of video data. Following the rather coarse resolution of these data, we exemplify some potential fields of application in science and education. We show a basic workflow how to produce 3D models and stereoscopic videos of the Earth’s surface. As a pre-study for videos with better spatial as well as radiometric resolution, the delivered products serve not only scientific purposes, but are integrated in school lessons to evoke the pupils’ fascination for earth sciences and space.

N-Acetylcystein: neue Option zur frühen Bekämpfung von Schizophrenie

Symptomfreiheit sowie Erhalt der Selbstbestimmung über die eigene Lebensführung gehören zu den Zielen der Schizophreniebehandlung. Die erreichten Genesungsraten sind jedoch eher moderat, was sich auch in den langfristigen Kosten für das Gesundheitssystem widerspiegelt. Die Prävention der Schizophrenie, mit dem Ziel attenuierte psychotische Symptome zu diagnostizieren, bevor eine manifeste Schizophrenie auftritt, steht daher im Fokus von Forschung und Praxis. Dazu gehören auch früh einsetzbare moderne Behandlungsmethoden mit geringem Nebenwirkungsprofil wie N-Acetylcystein.

In Memoriam: Gunter Menz

Remote Sensing Research Group, Department of Geography, University of Bonn, Meckenheimer Allee 166,53115 Bonn, Germany; andreas.rienow@ruhr-uni-bochum.de (A.R.); agatha.okhai@gmail.com (A.A.);hendrik.fluegel@googlemail.com (H.F.); s.heinemann@uni-bonn.de (S.H.); s6tohenn@uni-bonn.de (T.H.);k.hentze@geographie.uni-bonn.de (K.H.); f.kirimi@geographie.uni-bonn.de (F.K.);s6sokoch@uni-bonn.de (S.K.); bkoner@uni-bonn.de (B.K.-K.); s3anortw@uni-bonn.de (A.O.);schultz@giub.uni-bonn.de (J.S.); kstaar@uni-bonn.de (K.S.); kuria@geographie.uni-bonn.de (K.B.T.);anna.vetter@uni-bonn.de (A.V.)