@article{HaeussingerHeinzelHahnetal.2011, author = {Haeussinger, Florian B. and Heinzel, Sebastian and Hahn, Tim and Schecklmann, Martin and Ehlis, Ann-Christine and Fallgatter, Andreas J.}, title = {Simulation of Near-Infrared Light Absorption Considering Individual Head and Prefrontal Cortex Anatomy: Implications for Optical Neuroimaging}, series = {PLoS ONE}, volume = {6}, journal = {PLoS ONE}, number = {10}, doi = {10.1371/journal.pone.0026377}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-142311}, pages = {e26377}, year = {2011}, abstract = {Functional near-infrared spectroscopy (fNIRS) is an established optical neuroimaging method for measuring functional hemodynamic responses to infer neural activation. However, the impact of individual anatomy on the sensitivity of fNIRS measuring hemodynamics within cortical gray matter is still unknown. By means of Monte Carlo simulations and structural MRI of 23 healthy subjects (mean age: (25.0 +/- 2.8) years), we characterized the individual distribution of tissue-specific NIR-light absorption underneath 24 prefrontal fNIRS channels. We, thereby, investigated the impact of scalp-cortex distance (SCD), frontal sinus volume as well as sulcal morphology on gray matter volumes (V(gray)) traversed by NIR-light, i.e. anatomy-dependent fNIRS sensitivity. The NIR-light absorption between optodes was distributed describing a rotational ellipsoid with a mean penetration depth of (23.6 +/- 0.7) mm considering the deepest 5\% of light. Of the detected photon packages scalp and bone absorbed (96.4 +/- 9: 7)\% and V(gray) absorbed (3.1 +/- 1.8)\% of the energy. The mean V(gray) volume (1.1 +/- 0.4)cm(3) was negatively correlated (r = - .76) with the SCD and frontal sinus volume (r = - .57) and was reduced by 41.5\% in subjects with relatively large compared to small frontal sinus. Head circumference was significantly positively correlated with the mean SCD (r = .46) and the traversed frontal sinus volume (r = .43). Sulcal morphology had no significant impact on V(gray). Our findings suggest to consider individual SCD and frontal sinus volume as anatomical factors impacting fNIRS sensitivity. Head circumference may represent a practical measure to partly control for these sources of error variance.}, language = {en} } @article{HahnDreslerPykaetal.2013, author = {Hahn, Tim and Dresler, Thomas and Pyka, Martin and Notebaert, Karolien and Fallgatter, Andreas J.}, title = {Local Synchronization of Resting-State Dynamics Encodes Gray's Trait Anxiety}, series = {PLoS ONE}, volume = {8}, journal = {PLoS ONE}, number = {3}, doi = {10.1371/journal.pone.0058336}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-131057}, pages = {e58336}, year = {2013}, abstract = {The Behavioral Inhibition System (BIS) as defined within the Reinforcement Sensitivity Theory (RST) modulates reactions to stimuli indicating aversive events. Gray's trait Anxiety determines the extent to which stimuli activate the BIS. While studies have identified the amygdala-septo-hippocampal circuit as the key-neural substrate of this system in recent years and measures of resting-state dynamics such as randomness and local synchronization of spontaneous BOLD fluctuations have recently been linked to personality traits, the relation between resting-state dynamics and the BIS remains unexplored. In the present study, we thus examined the local synchronization of spontaneous fMRI BOLD fluctuations as measured by Regional Homogeneity (ReHo) in the hippocampus and the amygdala in twenty-seven healthy subjects. Correlation analyses showed that Gray's trait Anxiety was significantly associated with mean ReHo in both the amygdala and the hippocampus. Specifically, Gray's trait Anxiety explained 23\% and 17\% of resting-state ReHo variance in the left amygdala and the left hippocampus, respectively. In summary, we found individual differences in Gray's trait Anxiety to be associated with ReHo in areas previously associated with BIS functioning. Specifically, higher ReHo in resting-state neural dynamics corresponded to lower sensitivity to punishment scores both in the amygdala and the hippocampus. These findings corroborate and extend recent findings relating resting-state dynamics and personality while providing first evidence linking properties of resting-state fluctuations to Gray's BIS.}, language = {en} } @article{HahnKarolienDresleretal.2014, author = {Hahn, Tim and Karolien, Hilde and Dresler, Thomas and Kowarsch, Linda and Reif, Andreas and Fallgatter, Andreas J.}, title = {Linking online gaming and addictive behavior: converging evidence for a general reward deficiency in frequent online garners}, series = {Frontiers in Behavioral Neuroscience}, volume = {14}, journal = {Frontiers in Behavioral Neuroscience}, number = {8}, issn = {1662-5153}, doi = {10.3389/fnbeh.2014.00385}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-114737}, year = {2014}, abstract = {Millions of people regularly play so-called massively multiplayer online role playing games (MMORPGs). Recently, it has been argued that MMORPG overuse is becoming a significant health problem worldwide. Symptoms such as tolerance, withdrawal, and craving have been described. Based on behavioral, resting state, and task-related neuroimaging data, we test whether frequent players of the MMORPG "World of VVarcraft" (WoW) similar to drug addicts and individuals with an increased risk for addictions show a generally deficient reward system. In frequent players of the MMORPG "World of VVarcraft" (WoW-players) and in a control group of non-gamers we assessed (1) trait sensitivity to reward (SR), (2) BOLD responses during monetary reward processing in the ventral striatum, and (3) ventral-striatal resting-state dynamics. We found a decreased neural activation in the ventral striatum during the anticipation of both small and large monetary rewards. Additionally, we show generally altered neurodynamics in this region independent of any specific task for WoW players (resting state). On the behavioral level, we found differences in trait SR, suggesting that the reward processing deficiencies found in this study are not a consequence of gaming, but predisposed to it. These findings empirically support a direct link between frequent online gaming and the broad field of behavioral and drug addiction research, thus opening new avenues for clinical interventions in addicted gamers and potentially improving the assessment of addiction-risk in the vast population of frequent gamers.}, language = {en} }