@article{VernerHerrmannTrocheetal.2013, author = {Verner, Martin and Herrmann, Martin J. and Troche, Stefan J. and Roebers, Claudia M. and Rammsayer, Thomas H.}, title = {Cortical oxygen consumption in mental arithmetic as a function of task difficulty: a near-infrared spectroscopy approach}, series = {Frontiers in Human Neuroscience}, volume = {7}, journal = {Frontiers in Human Neuroscience}, number = {217}, issn = {1662-5161}, doi = {10.3389/fnhum.2013.00217}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-122449}, year = {2013}, abstract = {The present study investigated changes in cortical oxygenation during mental arithmetic using near-infrared spectroscopy (NIRS). Twenty-nine male volunteers were examined using a 52-channel continuous wave system for analyzing activity in prefrontal areas. With the help of a probabilistic mapping method, three regions of interest (ROIs) on each hemisphere were defined: The inferior frontal gyri (IFG), the middle frontal gyri (MFG), and the superior frontal gyri (SFG). Oxygenation as an indicator of functional brain activation was compared over the three ROI and two levels of arithmetic task difficulty (simple and complex additions). In contrast to most previous studies using fMRI or NIRS, in the present study arithmetic tasks were presented verbally in analogue to many daily life situations. With respect to task difficulty, more complex addition tasks led to higher oxygenation in all defined ROI except in the left IFG compared to simple addition tasks. When compared to the channel positions covering different gyri of the temporal lobe, the observed sensitivity to task complexity was found to be restricted to the specified ROIs. As to the comparison of ROIs, the highest oxygenation was found in the IFG, while MFG and SFG showed significantly less activation compared to IFG. The present cognitive-neuroscience approach demonstrated that NIRS is a suitable and highly feasible research tool for investigating and quantifying neural effects of increasing arithmetic task difficulty.}, language = {en} } @article{ManishNueckelMuehlbergeretal.2013, author = {Manish, Asthana and Nueckel, Katharina and M{\"u}hlberger, Andreas and Neueder, Dorothea and Polak, Thomas and Domschke, Katharina and Deckert, J{\"u}rgen and Herrmann, Martin J.}, title = {Effects of transcranial direct current stimulation on consolidation of fear memory}, series = {Frontiers in Neuropsychiatric Imaging and Stimulation}, journal = {Frontiers in Neuropsychiatric Imaging and Stimulation}, doi = {10.3389/fpsyt.2013.00107}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-97294}, year = {2013}, abstract = {It has been shown that applying transcranial direct current stimulation (tDCS) over the dorsolateral prefrontal cortex (DLPFC) influences declarative memory processes. This study investigates the efficacy of tDCS on emotional memory consolidation, especially experimental fear conditioning. We applied an auditory fear-conditioning paradigm, in which two differently colored squares (blue and yellow) were presented as conditioned stimuli (CS) and an auditory stimulus as unconditioned stimulus (UCS). Sixty-nine participants were randomly assigned into three groups: anodal, cathodal, and sham stimulation. The participants of the two active groups (i.e., anodal and cathodal) received tDCS over the left DLPFC for 12 min after fear conditioning. The effect of fear conditioning and consolidation (24 h later) was measured by assessing the skin conductance response (SCR) to the CS. The results provide evidence that cathodal stimulation of the left DLPFC leads to an inhibitory effect on fear memory consolidation compared to anodal and sham stimulation, as indicated by decreased SCRs to CS+ presentation during extinction training at day 2. In conclusion, current work suggests that cathodal stimulation interferes with processes of fear memory consolidation.}, language = {en} } @article{BiehlEhlisMuelleretal.2013, author = {Biehl, Stefanie C. and Ehlis, Ann-Christine and M{\"u}ller, Laura D. and Niklaus, Andrea and Pauli, Paul and Herrmann, Martin J.}, title = {The impact of task relevance and degree of distraction on stimulus processing}, series = {BMC Neuroscience}, journal = {BMC Neuroscience}, doi = {10.1186/1471-2202-14-107}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-97271}, year = {2013}, abstract = {Background The impact of task relevance on event-related potential amplitudes of early visual processing was previously demonstrated. Study designs, however, differ greatly, not allowing simultaneous investigation of how both degree of distraction and task relevance influence processing variations. In our study, we combined different features of previous tasks. We used a modified 1-back task in which task relevant and task irrelevant stimuli were alternately presented. The task irrelevant stimuli could be from the same or from a different category as the task relevant stimuli, thereby producing high and low distracting task irrelevant stimuli. In addition, the paradigm comprised a passive viewing condition. Thus, our paradigm enabled us to compare the processing of task relevant stimuli, task irrelevant stimuli with differing degrees of distraction, and passively viewed stimuli. EEG data from twenty participants was collected and mean P100 and N170 amplitudes were analyzed. Furthermore, a potential connection of stimulus processing and symptoms of attention deficit hyperactivity disorder (ADHD) was investigated. Results Our results show a modulation of peak N170 amplitudes by task relevance. N170 amplitudes to task relevant stimuli were significantly higher than to high distracting task irrelevant or passively viewed stimuli. In addition, amplitudes to low distracting task irrelevant stimuli were significantly higher than to high distracting stimuli. N170 amplitudes to passively viewed stimuli were not significantly different from either kind of task irrelevant stimuli. Participants with more symptoms of hyperactivity and impulsivity showed decreased N170 amplitudes across all task conditions. On a behavioral level, lower N170 enhancement efficiency was significantly correlated with false alarm responses. Conclusions Our results point to a processing enhancement of task relevant stimuli. Unlike P100 amplitudes, N170 amplitudes were strongly influenced by enhancement and enhancement efficiency seemed to have direct behavioral consequences. These findings have potential implications for models of clinical disorders affecting selective attention, especially ADHD.}, language = {en} } @article{KopfDreslerReichertsetal.2013, author = {Kopf, Juliane and Dresler, Thomas and Reicherts, Philipp and Herrmann, Martin J. and Reif, Andreas}, title = {The Effect of Emotional Content on Brain Activation and the Late Positive Potential in a Word n-back Task}, series = {PLoS ONE}, journal = {PLoS ONE}, doi = {10.1371/journal.pone.0075598}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-96687}, year = {2013}, abstract = {Introduction There is mounting evidence for the influence of emotional content on working memory performance. This is particularly important in light of the emotion processing that needs to take place when emotional content interferes with executive functions. In this study, we used emotional words of different valence but with similar arousal levels in an n-back task. Methods We examined the effects on activation in the prefrontal cortex by means of functional near-infrared spectroscopy (fNIRS) and on the late positive potential (LPP). FNIRS and LPP data were examined in 30 healthy subjects. Results Behavioral results show an influence of valence on the error rate depending on the difficulty of the task: more errors were made when the valence was negative and the task difficult. Brain activation was dependent both on the difficulty of the task and on the valence: negative valence of a word diminished the increase in activation, whereas positive valence did not influence the increase in activation, while difficulty levels increased. The LPP also differentiated between the different valences, and in addition was influenced by the task difficulty, the more difficult the task, the less differentiation could be observed. Conclusions Summarized, this study shows the influence of valence on a verbal working memory task. When a word contained a negative valence, the emotional content seemed to take precedence in contrast to words containing a positive valence. Working memory and emotion processing sites seemed to overlap and compete for resources even when words are carriers of the emotional content.}, language = {en} }