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Symposium 5_4: Recent advances in 3D Electron Microscopy for Neuroscience
Time:
Friday, 15/Sept/2023:
6:15pm - 7:30pm
Session Chair: Corrado Calì, Università degli Studi di Torino Session Chair: Maura Francolini, Università degli Studi di Milano
Location:Sala Parigi
75 seats
Sponsored by Zeiss
Session Abstract
Volume electron microscopy (vEM) and tomography allow visualization of cellular structure and ultrastructure at its finest detail. By means of computational tools, the complex three-dimensional architecture of the brain and its cellular processes can be revealed down to its synaptic connections. Large scale mapping, for instance revealed new connectivity patterns, thanks to connectomics, and 3D observations on organelles highlighted their intracellular strategic distribution, allowing scientist to confirm functional observations and nanolevel scale.
Presentations
6:15pm - 6:35pm
Widespread effects of sleep and sleep loss on synaptic ultrastructure
Luisa de Vivo
University of Camerino, Italy
We spent more than one third of our life sleeping and, yet the role of sleep remains one of the most unsolved mysteries of biology. Molecular and electrophysiological evidence indicates that sleep leads to a broad but selective weakening of many forebrain synapses, thus preventing wake related synaptic saturation and reducing the energy cost of synaptic activity. Dr de Vivo will discuss morphological changes in neuronal and glial synaptic structures across sleep and periods of wake of different duration, emphasizing the role of volume EM approaches in better defining the ultrastructural signatures of sleep and sleep loss at the synaptic level.
6:35pm - 6:55pm
Multiresolution 3D models of astrocytes and neurons to investigate Brain Energy Metabolism
Corrado Calì
Università degli Studi di Torino, Italy
Long-term memory formation is an energy-expensive process, which is accompanied by structural changes at synapses, such as an increase in spines’ volume and density. To directly investigate such changes, and their dependence on brain energy metabolism, we perform morphometric analysis on segmented 3D Electron Microscopy (EM) imaged volumes, using a set of custom-made tools tailored for our needs and pioneered the use of 3D analysis using virtual reality (VR). We focused our analysis on glycogen, a precursor of lactate, and an energy storage molecule explicitly expressed in astrocytes and inferred its spatial relationship with synaptic contacts. We compared the neuropil of mice undergoing a novel object recognition (NOR) in the presence or absence of a potent inhibitor of glycogenolysis, 1,4-Dideoxy-1,4-imino-D-arabinitol hydrochloride (DAB), already known to cause amnesia in rats. We found that the impairment in long-term memory formation correlated with failure to form new synapses, together with a decrease in the levels of glycogen, supposedly the source of lactate. A model of chemical LTP on hippocampal organotypic slices well correlated with the structural effects of learning on spine density and size in vivo. The application of DAB inhibited both LTP and spines turnover. The exogenous application of L-Lactate was able to rescue the behavioral phenotype on mice, and the density increase but not their size. VR analysis highlighted that the presence of glycogen correlated with the presence of synapses. Our results suggest that memory and LTP mobilize glycogen stores, that might accumulate around potentiated synapses.
New technologies and methods for 3D super and ultra-resolution microscopy using Light, Laser, X-Ray and Electron Microscopy have been emerging over the last two decades.
Researchers are showing success correlating data collected from light and/or X-ray and/or Electron microscopy. We will summarize briefly the challenges and opportunities of the new Volume EM (vEM) technologies, along with insights on how to build up a vEM and vCLEM community and support one another in this challenging and exciting journey of scientific discovery
