For FSCV recordings, cells were removed from the incubator and transported to the Faraday cages. Manual micromanipulators (Narashige Group, Japan) were used to submerge the CFMs into the media and approach the cells as close as possible without breaking. For PC12 measurements, we measured ~2-3 seconds of FSCV background before using a micropipette to exogenously apply 5 µM Trp into the media near the CFM while continuously recording for up to 60 seconds. This was repeated 4 more times at different locations in the well plate as well as in different culture plates for PC-12 cells. We performed these measurements 6 times for PC-12 cells with overexpression of TPH2. For pinealocytes, we measured baseline for 5 min (30 sec files, 30 sec in between), then added either media or norepinephrine, and continued to measure for 30 min.