Physical object Open Access
This system was designed to provide simple and reliable light shielding for 2-photon imaging in awake head-fixed mice (running on a 3D-treadmill with visual stimulation in our case). With this in mind, we optimized for the following criteria:
We came up with a two-part solution. One is a circular headplate with a ring that rises up conically to fit around the microscope lens while providing a fluid reservoir for imaging with water-immersed objectives. The headplate has two connectors on the side that can be used for stable head fixation (similar concept to Poort et al. 2015 Neuron, Havenith et al. 2019 Scientific Reports). It is easy to implant on the skull, and then remains stable and watertight for months.
The second component is a light-absorbing conical sleeve which was designed to fit with an Olympus 20x objective, and can be lowered below the rim of the implanted headplate once the animal is head-fixed under the microscope. Since the sleeve is designed to fit snugly underneath the rim of the headplate’s cone, it doesn’t require any extra fastening mechanisms apart from lowering it past the headplate’s rim, making it extremely quick and easy to use. In our experience, lowering the sleeve all the way to the base of the headplate eliminates all stray light in recordings.