NeuroImage
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Due to its crucial role for memory processes and its relevance in neurological and psychiatric disorders, the hippocampus has been the focus of neuroimaging research for several decades. In vivo measurement of human hippocampal volume and shape with magnetic resonance imaging has become an important element of neuroimaging research. Nevertheless, volumetric findings are still inconsistent and controversial for many psychiatric conditions including affective disorders. ⋯ These are major sources of variance between different protocols. In contrast, the definitions of the lateral, superior, and inferior borders are less disputed. Directing resources to replication studies that incorporate characteristics of the segmentation protocols presented herein may help resolve seemingly contradictory volumetric results between prior neuroimaging studies and facilitate the appropriate selection of protocols for manual or automated delineation of the hippocampus for future research purposes.
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The objective of this study was to investigate total volume and spatial distribution of white matter hyperintensities (WMH) in a large sample of newly diagnosed Parkinson's disease (PD) patients with and without mild cognitive impairment (MCI) compared to normal controls (NC). Furthermore, we aimed to examine the impact of the WMH on attention-executive performance in PD. MCI is regarded as a pre-dementia stage. ⋯ Analysis showed that there were no significant differences between the 3 groups in total volume or spatial distribution of WMH. In addition there was no significant relationship between total volume or spatial distribution of WMH and attention-executive functions in PD. We conclude that in this PD cohort, cognitive impairment seems to be independent of WMH damage.
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Both affective neuroscience and decision science focus on the role of emotions in decisions. Regret and disappointment are emotions experienced with negative decision outcomes. The present research examines the neural substrates of regret and disappointment as well as the role of regret and disappointment in decision making. ⋯ Both regret and disappointment activated anterior insula and dorsomedial prefrontal cortex relative to fixation, with greater activation in regret than in disappointment. In contrast to disappointment, regret also showed enhanced activation in the lateral orbitofrontal cortex. These findings suggest that regret and disappointment, emotions experienced during decision-related loss, share a general neural network but differ in both the magnitude of subjective feelings and with regret activating some regions with greater intensity.
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Resting-state data sets contain coherent fluctuations unrelated to neural processes originating from residual motion artefacts, respiration and cardiac action. Such confounding effects may introduce correlations and cause an overestimation of functional connectivity strengths. In this study we applied several multidimensional linear regression approaches to remove artificial coherencies and examined the impact of preprocessing on sensitivity and specificity of functional connectivity results in simulated data and resting-state data sets from 40 subjects. ⋯ Results in simulated data sets compared with result of human data strongly suggest that anticorrelations are indeed introduced by global signal regression and should therefore be interpreted very carefully. In addition, global signal regression may also reduce the sensitivity for detecting true correlations, i.e. increase the number of false negatives. Concluding from our results we suggest that is highly recommended to apply correction against realignment parameters, white matter and ventricular time courses, as well as the global signal to maximize the specificity of positive resting-state correlations.
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Blood oxygenation level dependent (BOLD) signal changes occurring during execution of a simple motor task were measured at field strengths of 1.5, 3 and 7 T using multi-slice, single-shot, gradient echo EPI at a resolution of 1x1x3 mm(3), to quantify the benefits offered by ultra-high magnetic field for functional MRI. Using four different echo times at each field strength allowed quantification of the relaxation rate, R(2)* and the change in relaxation rate on activation, DeltaR(2)*. ⋯ The number of pixels classified as active, the t-value calculated over a common region of interest and the percentage signal change in the same region were all found to peak at TE approximately T(2)* and increase significantly with field strength. An earlier onset of the haemodynamic response at higher field provides some evidence for a reduced venous contribution to the BOLD signal at 7 T.