NeuroImage
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In addition to the BOLD scan, quantitative functional MRI studies require measurement of both cerebral blood volume (CBV) and flow (CBF) dynamics. The ability to detect CBV and CBF responses in a single additional scan would shorten the total scan time and reduce temporal variations. Several approaches for simultaneous CBV and CBF measurement during functional MRI experiments have been proposed in two-dimensional (2D) mode covering one to three slices in one repetition time (TR). ⋯ We estimated this using Bloch simulations and demonstrate that the resulting 3D acquisition can detect activation patterns and relative signal changes of quality comparable to that of the original separate scans. The same was found for temporal signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). This approach provides improved acquisition efficiency when both CBV and CBF responses need to be monitored during a functional task.
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Evidence from magnetic resonance imaging (MRI) studies shows that healthy aging is associated with profound changes in cortical and subcortical brain structures. The reliable delineation of cortex and basal ganglia using automated computational anatomy methods based on T1-weighted images remains challenging, which results in controversies in the literature. In this study we use quantitative MRI (qMRI) to gain an insight into the microstructural mechanisms underlying tissue ageing and look for potential interactions between ageing and brain tissue properties to assess their impact on automated tissue classification. ⋯ These discrepancies between grey matter volume estimates can be attributed to R2* - a surrogate marker of iron concentration, and further modulation by an interaction between R2* and age, both in cortical and subcortical areas. We interpret our findings as direct evidence for the impact of ageing-related brain tissue property changes on automated tissue classification of brain structures using SPM12. Computational anatomy studies of ageing and neurodegeneration should acknowledge these effects, particularly when inferring about underlying pathophysiology from regional cortex and basal ganglia volume changes.
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Repetitive navigated transcranial magnetic stimulation (rTMS) is increasingly used for preoperative cortical language mapping. Unlike direct cortical stimulation (DCS), and due to its non-invasive character, this technique can provide a map of the distribution of human language in the healthy brain as well as a dysfunctional brain. Although functional magnetic resonance imaging (fMRI) studies have reported interhemispheric functional connectivity between language structures, the way in which the right hemisphere helps bring about language function remains only partially investigated. The present study therefore uses rTMS as a virtual lesion model to investigate the right hemisphere's contribution to language processing in the healthy human brain. ⋯ For the first time, the present study provides data on the right hemisphere's cortical regions causally related to single word production function (right opIFG, aSMG, pSMG, mSTG), and selectively in female brains (right pSTG), from a large sample of 50 healthy adult brains in a virtual-lesion design. Moreover, speech-motor control regions (right mPrG, vPrG, mPoG, vPoG) and cortical regions supporting language task performance (mMFG, pMFG) in the language-non-dominant right hemisphere are described.
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A recent meta-analysis by Hedman et al. allows for accurate estimation of brain volume changes throughout the life span. Additionally, Tate et al. showed that intracranial volume at a later point in life can be used to estimate reliably brain volume at an earlier point in life. These advancements were combined to create a model which allowed the estimation of brain volume just prior to injury in a group of patients with mild or moderate traumatic brain injury (TBI). This volume estimation model was used in combination with actual measurements of brain volume to test hypotheses about progressive brain volume changes in the patients. ⋯ During the first few months after injury, patients with mild or moderate TBI have rapid atrophy of WBP and CWM, and rapid enlargement of SCN+IFT. The magnitude and pattern of the changes in volume may allow for the eventual development of diagnostic tools based on the volume estimation approach.
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Although researchers generally concur that creativity involves the production of novel and useful products, the neural basis of creativity remains elusive due to the complexity of the cognitive processes involved. Recent studies have shown that highly creative individuals displayed more cognitive flexibility. However, direct evidence supporting the relationship between creativity and cognitive flexibility has rarely been investigated using both structural and functional neuroimaging techniques. ⋯ Moreover, the association between the dACC-mSFG connectivity and CAQ scores was mediated by cognitive flexibility, assessed by a task-switching paradigm. These findings indicate that individual differences in creative achievement are associated with both brain structure and corresponding intrinsic functional connectivity involved in cognitive flexibility and deliberate creative processing. Furthermore, dACC-mSFG connectivity may affect creative achievement through its impact on cognitive flexibility.