@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{KatzorkeZellerMuelleretal.2017,
  author    = {Katzorke, Andrea and Zeller, Julia B. M. and M{\"u}ller, Laura D. and Lauer, Martin and Polak, Thomas and Reif, Andreas and Deckert, J{\"u}rgen and Herrmann, Martin J.},
  title     = {Reduced activity in the right inferior frontal gyrus in elderly APOE-E4 carriers during a verbal fluency task},
  series = {Frontiers in Human Neuroscience},
  volume    = {11},
  journal   = {Frontiers in Human Neuroscience},
  doi       = {10.3389/fnhum.2017.00046},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-171892},
  year      = {2017},
  abstract  = {Apolipoprotein-E4 (APOE-E4) is a major genetic risk factor for developing Alzheimer's disease (AD). The verbal fluency task (VFT), especially the subtask category fluency, has shown to provide a good discrimination between cognitively normal controls and subjects with AD. Interestingly, APOE-E4 seems to have no effect on the behavioral performance during a VFT in healthy elderly. Thus, the purpose of the present study was to reveal possible compensation mechanisms by investigating the effect of APOE-E4 on the hemodynamic response in non-demented elderly during a VFT by using functional near-infrared spectroscopy (fNIRS). We compared performance and hemodynamic response of high risk APOE-E4/E4, -E3/E4 carriers with neutral APOE-E3/E3 non-demented subjects (N = 288; 70-77 years). No difference in performance was found. APOE-E4/E4, -E3/E4 carriers had a decreased hemodynamic response in the right inferior frontal junction (IFJ) with a corresponding higher response in the left middle frontal gyrus (MFG) during category fluency. Performance was correlated with the hemodynamic response in the MFG. We assume a compensation of decreased IFJ brain activation by utilizing the MFG during category fluency and thus resulting in no behavioral differences between APOE-groups during the performance of a VFT.},
  language  = {en}
}