Development of Observation Platform for Multi-Photon Confocal Imaging in Brains of Behaving Animals - a Novel Tool for Studying the Neuronal Circuits for Navigation and Memory
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Through a user-centered design approach various concepts that allows the observation of freely moving head fixed animals have been investigated and evaluated. Based on feedback from KI/CNC it was decided to make the detail design for a floating box movement platform. The principle used for this concept is considered prior art, however, the system that is in the market as of today, is too small to fulfill the requirements from KI/CNC. The designed observation tool is based on the head fixed animal being placed in a flat floored lightweight box under a microscope. To allow the mouse to walk the box is supported by a layer of air, eliminating friction between table and box, thus allowing the box to change position and orientation according to the animals movements. The project has involved testing of multiple configurations and shapes of boxes. The final design uses a circular shaped box of 1000 mm diameter, made of carbon fiber prepreg, having a surface area that is 30 times larger compared to currently available product in the market. A novel design for reduced air consumption and improved lift for the floating box has been developed. The pressure required to lift the floating box is small, thus a low pressure air source can be used to provide lift. In the center of the table, where the animal is fixed, a high pressure flow chamber is mounted. Supplying the air to a dense, yet permeable, material reduces air consumption, however it allows a high pressure to build up when a the surface of the box is forced towards the surface of the flow chamber. This is due to the higher static pressure when air velocity approaches zero. Air supply to the air tables plenum chamber and center chamber is provided from the central pressurized air system. Pressure regulators are used to control air flow. Additionally, an experimental setup is designed around the floating box and air table. This includes a microscope mounting platform that is supported on an optical table, allowing alignment with the laser source, providing a vibration free setup. Testing of the prototypes built during the project has proven that the head fixed animal is able to control the movements of the floating box, thus allowing for in vivo observations of neurons in a head fixed behaving animal, on a 30 times larger platform compared to products available as of today.