Fiber-optic calcium monitoring of dendritic activity in vivo.

Observing dendritic activity in active animals presents great challenges and there are currently not many options available. This protocol describes the fiber-optic-based "periscope" method for recording from populations of layer 5 (L5) neocortical pyramidal dendrites. This is an inexpensive, convenient, and robust method for recording dendritic activity during behavior. The limitations of this approach are discussed and tips are provided for how it might be adapted for different purposes and brain areas.