Saline-free preparation for chronic in vivo imaging in adult Drosophila

ABSTRACT

Longitudinal brain imaging is essential for understanding neural mechanisms, yet traditional methods for adult *Drosophila* require external saline, which limits preparation stability and duration. We present a saline-free, chronic preparation for repeated neural recording in adult *Drosophila* over multiple days. We describe a method for mounting flies and performing head surgery without external saline, resealing the opening with a transparent optical window. We demonstrate the utility of this approach by tracking single-neuron spiking and neuronal calcium dynamics over 7-10 days. This technique provides a stable, long-term interface for studying learning, memory, and aging in the fly brain.