Browsing by Author "Medel Sierralta, Vicente Nicolas"

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    The ascending arousal system promotes optimal performance through mesoscale network integration in a visuospatial attentional task
    (The Mit Press, 2021) Wainstein Bezamat Gabriel; Rojas Libano, Daniel; Medel Sierralta, Vicente Nicolas; Alnaes, Dag; Kolskar, Knut K.; Endestad, Tor; Laeng, Bruno; Ossandon Valdes Tomas; Crossley Karmelic, Nicolas Andrés; Matar, Elie; Shine, James M.
    In our daily lives, it is usual to encounter highly demanding cognitive tasks. They have been traditionally regarded as challenges that are solved mainly through cerebral activity, specifically via information-processing steps carried by neurons in the cerebral cortex. Activity in cortical networks thus constitutes a key factor for improving our understanding of cognitive processes. However, recent evidence has shown that evolutionary older players in the central nervous system, such as brain stem's ascending modulatory systems, might play an equally important role in diverse cognitive mechanisms. Our article examines the role of the ascending arousal system on large-scale network dynamics by combining pupillometry, functional MRI, and graph theoretical analysis.
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    Whole-brain neuronal MCT2 lactate transporter expression links metabolism to human brain structure and function
    (National Academy of Sciences, 2022) Medel Sierralta, Vicente Nicolas; Crossley Karmelic, Nicolas Andrés; Gajardo, Ivana; Muller, Eli; Barros L., Felipe; Shine, James N.; Sierralta, Jimena
    Brain activity is constrained by local availability of chemical energy, which is generatedthrough compartmentalized metabolic processes. By analyzing data of whole humanbrain gene expression, we characterize the spatial distribution of seven glucose andmonocarboxylate membrane transporters that mediate astrocyte–neuron lactate shuttletransfer of energy. We found that the gene coding for neuronal MCT2 is the onlygene enriched in cerebral cortex where its abundance is inversely correlated withcortical thickness. Coexpression network analysis revealed that MCT2 was the onlygene participating in an organized gene cluster enriched in K+dynamics. Indeed, theexpression of KATPsubunits, which mediate lactate increases with spiking activity, isspatially coupled to MCT2 distribution. Notably, MCT2 expression correlated withfluorodeoxyglucose positron emission tomography task-dependent glucose utilization.Finally, the MCT2 messenger RNA gradient closely overlaps with functional MRI brainregions associated with attention, arousal, and stress. Our results highlight neuronalMCT2 lactate transporter as a key component of the cross-talk between astrocytes andneurons and a link between metabolism, cortical structure, and state-dependent brain function.