Photomicrograph of activated LC-NE neurons (c-fos, blue) of DBHcre-TdTomato (red) mice transduced with the virus AAV1-ChR2-eYFP or AAV1- eYFP (green) which received blue-light optical stimulation (10-ms at 10 Hz blue light pulses over 500 ms every 20 seconds) in the LC for 20 minutes. This
experiment has been reproduced successfully on 6 mice per condition. Scale bars: 50 µm.