10th webinar: ILLUMINATING NEURONAL CIRCUIT
Dr Tommaso Fellin
Istituto Italiano di Tecnologia, Genova, IT
Link @ recorded talk
Aberration corrected microendoscopes for extended field-of-view deep brain imaging in benchtop and miniaturized two-photon microscopes
Neural population dynamics in deep regions of the brain play fundamental roles in crucial brain functions, from decision making to the processing of sensory information. A fundamental prerequisite to understand how neuronal population dynamics in the deep brain control such important behavioral processes is to sample large neuronal networks with high and homogeneous spatial resolution and minimal invasiveness. Current techniques based on two-photon microendoscopy are limited in achieving this goal. In this talk, I will present the development of aberration corrected microendoscopes to perform two-photon functional imaging over extended field-of-views in the deep brain of both head fixed mice and freely moving animals.
Bio
Tommaso Fellin graduated in Physics at the University of Padova in 1998 studying enzyme kinetics with time-resolved spectroscopy. From 1998 to 2003, as a PhD student in the Dept. of Biomedical Sciences at University of Padova, he investigated the biophysical properties of voltage-gated calcium channels and the functional consequences of mutations in calcium channels linked to human neurological disorders (supervisor, D. Pietrobon). During his first postdoctoral training period (2003-2004), he integrated electrophysiological and imaging techniques to study neuron-glia communication in brain slices (supervisors, G. Carmignoto and T. Pozzan). In 2005 he moved to the Dept. of Neuroscience at University of Pennsylvania School of Medicine as a senior post doctoral researcher and continued his research on neuron-glia interaction (supervisor, P. Haydon). In 2008, he joined the department of Neuroscience and Brain Technologies at the Italian Institute of Technology (IIT) as a junior Principal Investigator. He is currently senior Principal Investigator at the IIT, head of the Optical Approaches to Brain Function Laboratory, and co-head (together with Dr. S. Panzeri) of the Neural Coding Laboratory. He is recipient of the European Research Council (ERC) consolidator grant NEURO-PATTERNS, of the FIS3 Advanced grant OPTICA, and co-founder of the start-up SmartMicroOptics. He was Coordinator of the Neuroscience Area in 2019-2023. Since 2023, he serves as Associate Director for the Technologies for Life Sciences Domain at the IIT.
Dr Imane Bendifallah
Institut de la Vision, Sorbonne Univ., INSERM, CNRS, Paris, FR
Link @ recorded talk
Scanless two-photon voltage imaging
Parallel light-sculpting methods have been used to perform scanless two-photon photostimulation of multiple neurons simultaneously during all-optical neurophysiology experiments.
In this work, we demonstrate that scanless two-photon excitation is also suitable for voltage imaging. We present a characterization of scanless two-photon voltage imaging using existing parallel approaches and demonstrate voltage recordings of high-frequency spike trains and sub-threshold depolarizations in intact brain tissue from neurons expressing the voltage indicator JEDI-2P, from single and multiple cells in vitro and in vivo. We further demonstrate that scanless light-sculpting illumination methods enable two-photon voltage imaging of rhodopsin-based voltage indicators. These indicators are typically much brighter than those based on voltage sensing domains but have not previously been demonstrated to function under two-photon excitation.
Bio
Imane Bendifallah is a research engineer in the lab of Valentina Emiliani, at the Vision Institute in Paris. She earned her PhD in neuroscience from Sorbonne University in 2023. Her work is currently focused on optimizing and testing optical and optogenetic tools for two photon voltage imaging and all optical connectivity experiments.
Dr Francesco Gobbo
University of Edinburgh, Edinburgh, UK
Link @ recorded talk
Hippocampal reactivation of planned trajectories in an allocentric memory task in rats through miniature microscopes
It still remains unclear how the brain replays stored neural information, and whether such replay merely reflects past experiences or also plans of future endeavours. Hippocampal activity provides a representation of the world around us and our movement and navigation within that world, but it is not known if and to what extent the chosen navigational reference frame can influence hippocampal representations during memory-based tasks, including those focused on future activity. We developed and employ two naturalistic, carefully controlled variants of the everyday memory task to model the use of egocentric and allocentric coordinates in the same arena. By recording hippocampal neural activity through miniature microscopes in rats performing each of the two tasks, we uncover differences in the representation of space, and in the features of memory-based action planning. By also deploying optogenetic inactivation during navigational decision making, we find that hippocampal representations observed during the planning phase are necessary for solving the allocentric, but not the egocentric version of the task. Overall, our findings reveal a functional link between non-local hippocampal representations and allocentric navigation.
Bio
Dr Francesco Gobbo graduated in Molecular and Cellular Biology at Scuola Normale Superiore and the University of Pisa in 2011 and obtained his PhD in Neurobiology from Scuola Normale Superiore in 2018 under the supervision of Prof Antonino Cattaneo. He then joined the laboratory of Prof Richard Morris at the University of Edinburgh, where he pioneered the use of miniscopes to study episodic-like memory in rodents. He is currently working with Prof Tara Spires-Jones at the University of Edinburgh imaging synaptic activity in AD models. His scientific interests lie in the synaptic and cellular representation of memories in cognition and neurodegeneration.