Optogenetic Manipulation of Cerebellar Purkinje Cell Activity In Vivo

Purkinje cells (PCs) are the sole output neurons of the cerebellar cortex. Although their anatomical connections and physiological response properties have been extensively studied, the causal role of their activity in behavioral, cognitive and autonomic functions is still unclear because PC activity cannot be selectively controlled. Here we developed a novel technique using optogenetics for selective and rapidly reversible manipulation of PC activity in vivo. We injected into rat cerebellar cortex lentiviruses expressing either the light-activated cationic channel channelrhodopsin-2 (ChR2) or light-driven chloride pump halorhodopsin (eNpHR) under the control of the PC-specific L7 promoter. Transgene expression was observed in most PCs (ChR2, 92.6%; eNpHR, 95.3%), as determined by immunohistochemical analysis. In vivo electrophysiological recordings showed that all light-responsive PCs in ChR2-transduced rats increased frequency of simple spike in response to blue laser illumination. Similarly, most light-responsive PCs (93.8%) in eNpHR-transduced rats decreased frequency of simple spike in response to orange laser illumination. We then applied these techniques to characterize the roles of rat cerebellar uvula, one of the cardiovascular regulatory regions in the cerebellum, in resting blood pressure (BP) regulation in anesthetized rats. ChR2-mediated photostimulation and eNpHR-mediated photoinhibition of the uvula had opposite effects on resting BP, inducing depressor and pressor responses, respectively. In contrast, manipulation of PC activity within the neighboring lobule VIII had no effect on BP. Blue and orange laser illumination onto PBS-injected lobule IX didn't affect BP, indicating the observed effects on BP were actually due to PC activation and inhibition. These results clearly demonstrate that the optogenetic method we developed here will provide a powerful way to elucidate a causal relationship between local PC activity and functions of the cerebellum

Active tectonics and fault evolution in the Western Balkans

This article has been accepted for publication in Geophysical Journal International ©:The Author(s) 2022. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.Uploaded in accordance with the publisher's self-archiving policy. All rights reserved.The western Balkans occupy a region influenced by two major active tectonic processes: the collision between the Adriatic Region and the Dinarides in the west, and the extension of the Aegean Region and its surroundings as they move towards the Hellenic Trench. An understanding of the kinematics and dynamics of the western Balkans has significance for our understanding of continental tectonics in general, and is the object of this paper. The region is rich in observational data, with many well-studied earthquakes, good geodetic coverage by GNSS (Global Navigation Satellite System) and abundant exposure of active faulting and its associated geomorphology, especially within the Mesozoic carbonates that cover large sectors of the extensional areas. We first use such observations to establish the regional kinematic patterns, by which we mean a clarification of how active faulting achieves the motions observed in the deforming velocity field obtained from GNSS measurements. We then use geomorphological observations on the evolution of drainage systems to establish how kinematic and faulting patterns have changed and migrated during the Late Neogene-Quaternary. The kinematics, and its evolution, can then be used to infer characteristics of the dynamics, by which we mean the origin and effect of the forces that control the overall deformation. The principal influences are: (i) the distribution and evolution of gravitational potential energy (GPE) contrasts arising from crustal thickness variations and elevation, in particular the growth of topography by shortening in the Albanides–Hellenides mountain ranges and the high elevation of mainland Greece relative to the Mediterranean seafloor and (ii) the ability of the boundaries of the region, along the Adriatic coast and in the Hellenic Trench, to support the forces arising from those GPE contrasts. The evolution in space and time indicates an interaction between the anisotropic strength fabric of the upper crust associated with faulting, and the more distributed and smoother patterns of flow that are likely to characterize the ductile deformation of the lower, aseismic part of the lithosphere—both of which influence the deformation on the scale of 100–200 km. The persistent argument about whether continental deformation is best described by a continuum or by rigid-block motions is largely a matter of scale and particular location: both are influential in establishing the patterns we see.Published2102–21262T. Deformazione crostale attivaJCR Journa

Bidirectional regulation of neurite elaboration by alternatively spliced metabotropic glutamate receptor 5 (mGlur5) isoforms

Alternative splicing in the mGluR5 gene generates two different receptor isoforms, of which expression is developmentally regulated. However, little is known about the functional significance of mGluR5 splice variants. We have examined the functional coupling, subcellular targeting, and effect on neuronal differentiation of epitope-tagged mGluR5 isoforms by expression in neuroblastoma NG108-15 cells. We found that both mGluR5 splice variants give rise to comparable [Ca2+]i transients and have similar pharmacological profile. Tagged receptors were shown by immunofluorescence to be inserted in the plasma membrane. In undifferentiated cells the subcellular localization of the two mGluR5 isoforms was partially segregated, whereas in differentiated cells the labeling largely redistributed to the newly formed neurites. Interestingly, we demonstrate that mGluR5 splice variants dramatically influence the formation and maturation of neurites; mGluR5a hinders the acquisition of mature neuronal traits and mGluR5b fosters the elaboration and extension of neurites. These effects are partly inhibited by MPEP