Moritz Berger

Detaching from the negative by reappraisal: the role of right superior frontal gyrus (BA9/32)

The ability to reappraise the emotional impact of events is related to long-term mental health. Self-focused reappraisal (REAPPself), i.e., reducing the personal relevance of the negative events, has been previously associated with neural activity in regions near right medial prefrontal cortex, but rarely investigated among brain-damaged individuals. Thus, we aimed to examine the REAPPself ability of brain-damaged patients and healthy controls considering structural atrophies and gray matter intensities, respectively. Twenty patients with well-defined cortex lesions due to an acquired circumscribed tumor or cyst and 23 healthy controls performed a REAPPself task, in which they had to either observe negative stimuli or decrease emotional responding by REAPPself. Next, they rated the impact of negative arousal and valence. REAPPself ability scores were calculated by subtracting the negative picture ratings after applying REAPPself from the ratings of the observing condition. The scores of the patients were included in a voxel-based lesion-symptom mapping (VLSM) analysis to identify deficit related areas (ROI). Then, a ROI group-wise comparison was performed. Additionally, a whole-brain voxel-based-morphometry (VBM) analysis was run, in which healthy participants REAPPself ability scores were correlated with gray matter intensities. Results showed that (1) regions in the right superior frontal gyrus (SFG), comprising the right dorsolateral prefrontal cortex (BA9) and the right dorsal anterior cingulate cortex (BA32), were associated with patients impaired down-regulation of arousal, (2) a lesion in the depicted ROI occasioned significant REAPPself impairments, (3) REAPPself ability of controls was linked with increased gray matter intensities in the ROI regions. Our findings show for the first time that the neural integrity and the structural volume of right SFG regions (BA9/32) might be indispensable for REAPPself. Implications for neurofeedback research are discussed.

Partial volume correction for in vivo 23Na-MRI data of the human brain

The concentration of sodium is a functional cell parameter and absolute quantification can be interesting for diagnostical purposes. The accuracy of sodium magnetic resonance imaging ((23)Na-MRI) is strongly biased by partial volume effects (PVEs). Hence our purpose was to establish a partial volume correction (PVC) method for (23)Na-MRI. The existing geometric transfer matrix (GTM) correction method was transferred from positron emission tomography (PET) to (23)Na-MRI and tested in a phantom study. Different parameters, as well as accuracy of registration and segmentation were evaluated prior to first in vivo measurements. In vivo sodium data-sets of the human brain were obtained at B0=7T with a nominal spatial resolution of (3mm)(3) using a density adapted radial pulse sequence. A volunteer study with four healthy subjects was performed to measure partial volume (PV) corrected tissue sodium concentration (TSC) which was verified by means of an intrinsic correction control. In the phantom study the PVC algorithm yielded a good correction performance and reduced the discrepancy between the measured sodium concentration value and the expected value in the smallest compartments of the phantom by 11% to a mean PVE induced discrepancy of 5.7% after correction. The corrected in vivo data showed a reduction of PVE bias for the investigated compartments for all volunteers, resulting in a mean reduction of discrepancy between two separate CSF compartments from 36% to 7.6%. The absolute TSC for two separate CSF compartments (sulci, lateral ventricles), gray and white brain matter after correction were 129±8mmol/L, 138±4mmol/L, 48±1mmol/L and 43±3mmol/L, respectively. The applied PVC algorithm reduces the PV-bias in quantitative (23)Na-MRI. Accurate, high-resolution anatomical data is required to enable appropriate PVC. The algorithm and segmentation approach is robust and leads to reproducible results.

In vivo assessment of cold stimulation effects on the fat fraction of brown adipose tissue using DIXON MRI

To evaluate the volume and changes of human brown adipose tissue (BAT) in vivo following exposure to cold using magnetic resonance imaging (MRI).

The traveling heads: multicenter brain imaging at 7 Tesla.

ObjectiveThis study evaluates the inter-site and intra-site reproducibility of 7 Tesla brain imaging and compares it to literature values for other field strengths.Materials and methodsThe same two subjects were imaged at eight different 7 T sites. MP2RAGE, TSE, TOF, SWI, EPI as well as B1 and B0 field maps were analyzed quantitatively to assess inter-site reproducibility. Intra-site reproducibility was measured with rescans at three sites.ResultsQuantitative measures of MP2RAGE scans showed high agreement. Inter-site and intra-site reproducibility errors were comparable to 1.5 and 3 T. Other sequences also showed high reproducibility between the sites, but differences were also revealed. The different RF coils used were the main source for systematic differences between the sites.ConclusionOur results show for the first time that multi-center brain imaging studies of the supratentorial brain can be performed at 7 T with high reproducibility and similar reliability as at 3T. This study develops the basis for future large-scale 7 T multi-site studies.

Nuclear-Overhauser-enhanced MR imaging of (31)P-containing metabolites: multipoint-Dixon vs. frequency-selective excitation.

The purpose of this study is to develop nuclear-Overhauser-enhanced (NOE) [(1)H]-(31)P magnetic resonance imaging (MRI) based on 3D fully-balanced steady-state free precession (fbSSFP). Therefore, two implementations of a 3D fbSSFP sequence are compared using frequency-selective excitation (FreqSel) and multipoint-Dixon (MP-Dixon). (31)P-containing model solutions and four healthy volunteers were examined at field strengths of B0=3T and 7T. Maps of the distribution of phosphocreatine (PCr), inorganic phosphate (Pi), and adenosine 5´-triphosphate (ATP) in the human calf were obtained with an isotropic resolution of 1.5cm (1.0cm) in an acquisition time of 5min (10min). NOE-pulses had the highest impact on the PCr acquisitions enhancing the signal up to (82 ± 13) % at 3T and up to (37 ± 9) % at 7T. An estimation of the level of PCr in muscle tissue from [(1)H]-(31)P MRI data yielded a mean value of (33 ± 8) mM. In conclusion, direct [(1)H]-(31)P imaging using FreqSel as well as MP-Dixon is possible in clinically feasible acquisition times. FreqSel should be preferred for measurements where only a single metabolite resonance is considered. MP-Dixon performs better in terms of SNR if a larger spectral width is of interest.

In vivo visualization of mesoscopic anatomy of healthy and pathological lymph nodes using 7T MRI: A feasibility study

To evaluate whether inguinal lymph nodes (LNs) may be visualized in vivo using 7T magnetic resonance imaging (MRI) at high spatial resolution.

In vivo visualization of mesoscopic anatomy of healthy and pathological lymph nodes using 7T MRI

To evaluate whether inguinal lymph nodes (LNs) may be visualized in vivo using 7T magnetic resonance imaging (MRI) at high spatial resolution.

Different roads to the same destination - The impact of impulsivity on decision-making processes under risk within a rewarding context in a healthy male sample.

The results of research about the influences of impulsivity on decision-making in situations of risk have been inconsistent. In this study, we used functional magnetic resonance imaging to examine the neural correlates of decision-making under risk in 12 impulsive, as defined by the Barratt Impulsiveness Scale-11, and 13 normal men. Although both groups showed similar decision-making behavior, neural activation regarding decision-making processes differed significantly. Impulsive persons revealed stronger activation in the (ventro-) medial prefrontal cortex and less deactivation of the orbitofrontal cortex while playing for potential gains. These brain regions might be associated with the emotional components of decision-making processes. Significant differences in brain areas linked to cognitive decision-making components were not found. This activation pattern might be seen as an indication for a hypersensitivity to rewarding cues in impulsive persons and might be linked to the propensity for inappropriate risk-taking behavior in persons with more extreme impulsivity levels, especially in situations in which they have a strong emotional involvement in the decision process.

Multi-contrast T2 ⁎ -relaxometry upon visual stimulation at 3 T and 7 T

This study aims to quantify the mean change of the effective transverse relaxation time T2(⁎) in active brain regions of human volunteers at field strengths of B0=3T and 7T. Besides the mono-exponential signal decay model an extended model is tested that considers mesoscopic field gradients across imaging voxels. Both models are checked for cross-talk and correlations between the parameters. A visual checkerboard-stimulation experiment with pause and stimulation periods of 50s and six repetitions was performed on healthy volunteers. Eleven contrasts were acquired in about 1.47s/1.43s at 3T/7T using a segmented multi-contrast echo-planar imaging (EPI) sequence. Average BOLD-signal time courses were calculated in a multi-step (non-)linear least-squares process. Baseline T2(⁎) values of 37.72ms/24.99ms (47.34ms/33.71ms) with stimulus-correlated changes ∆T2(⁎)of 1.32ms/0.74ms (1.99ms/1.43ms) resulted from the mono-exponential (extended) model for 3T/7T. A dependence of those values on the initial intensity S0 was observed. Stimulus-correlated changes of S0 in the order of 1% were measured at both field strengths. The mono-exponential model was found to be less prone to instabilities in the regression of both parameters. Signal alterations due to inflow were observed. Measured relaxation times agree with values from literature using repetitive stimulation. A strong dependence of the measured relaxation times on the inflow-related model parameter was found for both models. The extended model is applicable to dynamic neurofunctional measurements, but is currently limited due to the low number of contrasts acquired.

Corrigendum: Detaching from the negative by reappraisal: the role of right superior frontal gyrus (BA9/32)

We noticed an error in one of our presented analyses. One mismatched brain image was accidentally included in the voxel-based-morphometry (VBM) analysis. Thus, arousal and valence values were consecutively not properly assigned to the morphological brain data of the other included participants. Of three analyses implemented in this study (VSLM, ROI-based), only the VBM analysis was affected but the others remain untouched. Therefore, we re-conducted the whole VBM analysis with the correct allocation of data. The corrected results showed changes in the whole-brain and regional correlations compared to the originally presented results. However, the correlations in the expected areas of the original manuscript remain significant for arousal and valence difference scores. Fortunately, these results do not impact the main implications and neither invalidate the conclusions derived from the study nor introduce differing directions of inference. The right superior frontal gyrus (SFG/BA9) and anterior cingulate cortex (ACC/BA32) remain significant at whole-brain p < 0.001 uncorrected level, and the ROI analysis still showed significant correlations with gray matter intensities in the right SFG (BA9). The corrected results affect Figures ​Figures6,6, ​,7,7, Tables ​Tables5,5, ​,6,6, and small parts in results and discussion which are attached below. Figure 6 Whole brain patterns of gray matter volumes correlated with task performance in controls. (A) Arousal rating differences and (B) Valence rating differences (presented at a level of p < 0.001 unc). Figure 7 Graphic display of regional gray matter patterns of volume using the ROI depicted by the VLSM analysis (BA9/32) correlated with task performance in controls for (A) Arousal and (B) Valence rating differences (presented at a level of p < 0.05 unc) ... Table 5 Whole brain Patterns of GM volume correlated with task performance in controls. Table 6 Regional brain Patterns of GM volume correlated with task performance in controls. The authors deeply regret this error and apologize for any confusion it might have caused.