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Séminaire - Zoltan Szadai Activity of VIP and PV interneurons in vivo using single-cell resolution Calcium imaging

Abstract :

Vasoactive intestinal polypeptide (VIP) demarcates a small, unique population of inhibitory interneurons, making up 1-2% of all neocortical neurons. VIP interneurons are mainly located in the superficial layers of the neocortex and provide inhibition onto other inhibitory interneurons, most SOM and a fraction of PV neurons, thus disinhibiting principal cells. While the circuit impact of VIP interneurons has been well characterized, less is understood about their behavioral function. Here we set out to examine how VIP interneurons respond during simple choice behaviors.

Measuring of sparse interneuron populations as the VIPs, is a challenging imaging task. Our aim was to record activity of over 100 interneurons simultaneously, while mice are behaving. We developed an improved 2P 3D acousto-optic microscope, and new scanning methods capable of measuring hundreds of neuronal somata. The near-cubic-millimeter scan range, with a high scanning speed (up to 500 pts per kHz), with 470 nm × 490 nm × 2,490 nm resolution in the center core and less than 1.9 μm × 1.9 μm × 7.9 μm resolution throughout the entire scanning volume allows us a very precise functional mapping at different areas and depths of the mouse neocortex.
We also developed a high-precision motion artifact compensation algorithm to make possible valid measurement of small neural tissue volumes during activity.
Here I present the results, analysis and interpretation of this series of measurements along with the motion-compensation algorithm and its possible uses in in vivo experiments with behaving animals.

Selected publications

1. Szalay, G., Judák, L., Katona, G., Ócsai, K., Juhász, G., Veress, M., Szadai, Z., Fehér, A., Tompa, T., Chiovini, B., et al. (2016). Fast 3D Imaging of Spine, Dendritic, and Neuronal Assemblies in Behaving Animals. Neuron 92, 723-738

2. Chiovini, B., Turi, G.F., Katona, G., Kaszas, A., Palfi, D., Maak, P., Szalay, G., Szabo, M.F., Szabo, G., Szadai, Z., et al. (2014). Dendritic spikes induce ripples in parvalbumin interneurons during hippocampal sharp waves. Neuron 82, 908-924.