Dr. Michele Sorelli Profile

Dr. Michele Sorelli

at LENS - Lab Europeo di Spettroscopie Non-Lineari

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Publications (2)

Proceedings Article | 25 April 2023 Presentation + Paper

Fast multi-photon brain-wide volumetric imaging and photostimulation

Lapo Turrini, Pietro Ricci, Giuseppe de Vito, Michele Sorelli, Marco Marchetti, Francesco Vanzi, Ludovico Silvestri, Francesco Saverio Pavone

Proceedings Volume 12384, 123840B (2023) https://doi.org/10.1117/12.2649824

KEYWORDS: Optogenetics, Photostimulation, Neurons, Brain, Neuroimaging, Calcium, Microscopy, Light sources and illumination, Imaging systems, Biological imaging

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Proceedings Article | 30 May 2022 Presentation

An AOD breakthrough for volumetric 2P optogenetic applications

Pietro Ricci, Marco Marchetti, Michele Sorelli, Lapo Turrini, Francesco Resta, Vladislav Gavryusev, Giuseppe de Vito, Giuseppe Sancataldo, Francesco Vanzi, Ludovico Silvestri, Francesco Pavone

Proceedings Volume PC12144, PC1214406 (2022) https://doi.org/10.1117/12.2620313

KEYWORDS: Optogenetics, Photostimulation, Brain, Spatial light modulators, Optical design, Neurons, Mirrors, Pathology, Microscopy, Laser scanners

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To understand the brain computation paradigms and the causal interactions in complex neuronal networks, we need methods and technologies to record and perturb neuronal distributions over large fields of view. In this application, two-photon (2P) imaging has become a cornerstone microscopy technique, widely used for deep optical access in biological samples and selective light targeting with submicrometric resolution. In parallel to structural and functional imaging, 2P optogenetics has represented a game-changer, allowing targeted stimulation of specific neural circuits. However, the long commutation times and refresh rates of traditional scanning methods substantially hinder near-simultaneous multi-site 3D stimulation. Acousto-optic deflectors (AODs), owing to their fastest scanning and refresh rates, can fulfil the temporal requirements for concurrent activation of sparsely distributed neurons. Nevertheless, their applicability to 2P optogenetics in large volumes has been limited so far by the massive efficiency drop along the optical axis during their use in axial scanning. To counteract this drawback, a compensation software module is frequently employed to flatten the power distribution throughout the volume. However, the power threshold is reduced to the minimum intensity value addressable, lowering the peak intensity released in the centre of the axial scan. Here, we propose a unique approach for overcoming this drawback which provided lifted axial power distribution while maintaining a uniform lateral illumination range. We tested this method by the 2P photoactivation of optogenetic actuators in 3D in zebrafish larvae, showing how the probability of evoking an electrophysiological response and the relative neuronal activity amplitude improved by carefully optimizing the light targeting time on different axial planes. In conclusion, fast and uniform axial light addressing with AODs enables unprecedented 3D 2P optostimulation, formerly not feasible. Furthermore, this approach can be adopted as an upgrade for existing microscopes designed for volumetric imaging, providing 3D multi-site imaging and random-access illumination.

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