Brain structure & function
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During the course of adolescence, reductions occur in cortical thickness and gray matter (GM) volume, along with a 65% reduction in slow-wave (delta) activity during sleep (SWA) but empirical data linking these structural brain and functional sleep differences, is lacking. Here, we investigated specifically whether age-related differences in cortical thickness and GM volume and cortical thickness accounted for the typical age-related difference in slow-wave (delta) activity (SWA) during sleep. 132 healthy participants (age 12-21 years) from the National Consortium on Alcohol and NeuroDevelopment in Adolescence study were included in this cross-sectional analysis of baseline polysomnographic, electroencephalographic, and magnetic resonance imaging data. ⋯ Replacing age with pubertal status in models produced similar results. As reductions in GM volume and cortical thickness likely indicate synaptic pruning and myelination, these results suggest that diminished SWA in older, more mature adolescents may largely be driven by such processes within a number of frontal and parietal brain regions.
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Traumatic brain injury (TBI) is a leading cause of disability and death and survivors often suffer from long-lasting motor impairment, cognitive deficits, anxiety disorders and epilepsy. Few experimental studies have investigated long-term sequelae after TBI and relations between behavioral changes and neural activity patterns remain elusive. We examined these issues in a murine model of TBI combining histology, behavioral analyses and single-photon emission computed tomography (SPECT) imaging of regional cerebral blood flow (CBF) as a proxy for neural activity. ⋯ In the ipsilateral hemisphere, increased baseline neural activity was found in the amygdala. In the contralateral hemisphere, homotopic to the structural brain damage, the hippocampus and distinct cortex regions displayed increased baseline neural activity. Thus, regionally elevated CBF along with behavioral alterations indicate that increased neural activity is critically involved in the long-lasting consequences of TBI.
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The mirror neuron system (MNS) is a brain network that has been associated with the understanding of the actions performed by others. The main areas of the brain that are considered as belonging to the MNS are the rostral part of the inferior parietal lobe (IPL) and the inferior frontal gyrus (IFG). Many studies have tried to focus on the relationship between the regions belonging to the MNS, but a little consideration has been given to the study of the MNS in resting conditions. ⋯ This analysis revealed the existence of a functional connectivity within regions forming the core of MNS network and also with other regions with mirror properties. Finally, resting-state fMRI ICA showed the same functional network, although it was more restricted to the core MNS regions. To the best of our knowledge, this is the first study that approaches the MNS using the resting-state fMRI analysis using independent component analysis and functional connectivity at the same time.
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The claustrum is a brain region whose function remains unknown, though many investigators suggest it plays a role in conscious attention. Resting-state functional magnetic resonance imaging (RS-fMRI) has revealed how anesthesia alters many functional connections in the brain, but the functional role of the claustrum with respect to the awake versus anesthetized states remains unknown. Therefore, we employed a combination of seed-based RS-fMRI and neuroanatomical tracing to reveal how the anatomical connections of the claustrum are related to its functional connectivity during quiet wakefulness and the isoflurane-induced anesthetic state. ⋯ During deep isoflurane anesthesia, the functional connections of the claustrum with mPFC and MD were significantly attenuated, while those with the rest of cortex were not significantly altered. These changes in claustral functional connectivity were also observed when seeds were placed in mPFC or MD during RS-fMRI comparisons of the awake and deeply anesthetized states. Collectively, these data indicate that the claustrum has functional connections with mPFC and MD-thalamus that are significantly lessened by anesthesia.
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Despite its significant functional and clinical interest, the anatomy of the uncinate fasciculus (UF) has received little attention. It is known as a 'hook-shaped' fascicle connecting the frontal and anterior temporal lobes and is believed to consist of multiple subcomponents. However, the knowledge of its precise connectional anatomy in humans is lacking, and its subcomponent divisions are unclear. ⋯ The present results shed new light on the UF cortical terminations and its multicomponent internal organization with extended cortical connections within the frontal and temporal cortices. The different lateralization patterns we report within the UF subcomponents reconcile the conflicting asymmetry findings of the literature. Such results clarifying the UF structural anatomy lay the groundwork for more targeted investigations of its functional role, especially in semantic language processing.