Two-photon imaging of neural activity in awake, head-restrained mice

Two-photon microscopy has become an invaluable tool for visualizing the activity of neuronal populations at cellular resolution in vivo. Imaging typically requires restraining the head of the animal underneath the objective of a dedicated optical setup and experiments are therefore often performed under anesthesia. Here, we describe a method that allows imaging in awake mice with minimal motion artifacts and without the need for extensive training of the animal. We detail the necessary surgical procedures to chronically implant a small, lightweight headplate and to create a clear window for imaging. The design of a simple apparatus capable of stably accommodating the headplate while the mouse is positioned on a wheel with spring suspension is presented. When used in combination with a multiphoton microscope, this approach greatly facilitates optical recordings in nonanesthetized animals and opens the door to many projects that can bridge the gap between neural activity and behavior.