WT animals were prepared with headbar surgery as described above, with the addition of a 200 μm, 0.39 NA optical fiber (Thorlabs FT200UMT, flat cut) chronically implanted into the brain and affixed to the skull during headbar surgery. The optical fiber was implanted at −1.0 AP, 2.0 ML, −3.0 DV and angled at 30 degrees from vertical in the posterior direction, to ensure ~1 mm of distance between the fiber tip and the thermocouple. Craniectomy sites were the same as for recordings.
Mice were allowed to recover for two weeks then acclimated to head fixation as described above. Following acclimation, a craniectomy was made over marked sites and animals were recorded from the following day. Temperature recordings were performed with an OMEGA DAQ acquisition system (model 2401) coupled to a T-type hypodermic thermocouple (MT 29/5, Physitemp) using OMEGA DAQ CENTRAL software 1.0.7. The thermocouple was coated in CM DiI (Thermofisher) to mark the tract and inserted acutely using a micromanipulator. After allowing temperature to stabilize, temperature change in response to laser illumination was recorded. Each laser power was delivered 30 times, with 5 second pulse duration and 20 second interval between onset of laser pulses.
Mice were allowed to recover for two weeks then acclimated to head fixation as described above. Following acclimation, a craniectomy was made over marked sites and animals were recorded from the following day. Temperature recordings were performed with an OMEGA DAQ acquisition system (model 2401) coupled to a T-type hypodermic thermocouple (MT 29/5, Physitemp) using OMEGA DAQ CENTRAL software 1.0.7. The thermocouple was coated in CM DiI (Thermofisher) to mark the tract and inserted acutely using a micromanipulator. After allowing temperature to stabilize, temperature change in response to laser illumination was recorded. Each laser power was delivered 30 times, with 5 second pulse duration and 20 second interval between onset of laser pulses.