Multi-layer Cortical Ca²⁺ Imaging in Freely Moving Mice with Prism Probes and Miniaturized Fluorescence Microscopy

Here, we present a procedure for performing large-scale Ca²⁺ imaging with cellular-resolution across multiple cortical layers in freely moving mice. Hundreds of active cells can be observed simultaneously using a miniature, head-mounted microscope coupled with an implanted prism probe.