Physiotel

Rats were implanted with transmitters (Physiotel, Data Sciences International, St. Paul, MN, USA) for continuous wireless recording of body temperature, as previously described [24 (link)]. In brief, animals were anaesthetized with subcutaneous injection of a mixture of fentanyl 0.277 mg/kg, fluanizone 8.8 mg/kg, and midazolam 2.5 mg/kg (Hypnorm, Janssen, Beerse, Belgium; Dormicum, Roche, Basel, Switzerland; Midazolam Actavis, Actavis, Parsippany-Troy Hills, NJ, USA), and the transmitters were placed in subcutaneous pockets in the dorsomedial lumbar region (4ET transmitters) or in the neck region (F40-EET transmitters). Animals were allowed to recover for 14 days before entering the experiment. Body temperature was recorded every 10 s, at 50 Hz sampling rate, and signals were collected with Dataquest ART software (version 4.1, Data Sciences International, St. Paul, MN, USA). Chronos-Fit software (Heidelberg University, Heidelberg, Germany) [25 ] was used for linear analyses of body temperature. From the linear analysis, 24 h mean, 12 h rest phase mean (lights on; ZT 12–24), and 12 h active phase mean (lights off; ZT 0–12) were calculated.

For 3 of the 4 experiments, marmosets were tested in a specially designed sound-attenuated testing apparatus in a separate room (the remaining experiment took place in the home cage). Marmosets were initially trained to enter a Perspex carry box in exchange for a small amount of marshmallow reward. The box was brought to the testing room and slotted into a chamber within the testing apparatus. The chamber was fitted with a houselight (LED light strip, 3W), 3 cameras attached to the top of the chamber, and a speaker (Behringer) and microphone concealed behind a panel. A telemetry receiver for the relaying of cardiovascular data was located under the floor of the chamber (Physiotel, Data Sciences International). All data from the receiver were recorded and analyzed using Spike 2 software (Cambridge Electronic Design). Video footage obtained using the cameras in the chamber was recorded using Power Director software (Cyberlink).

Mice were anesthetized with isoflurane (3.5%) and maintained under anesthesia (2-2.5%) throughout the surgery. Mice received analgesia (carprofen, 5 mg/kg, i.p.) before the start of surgery. A PhysioTel miniature implantable radio-telemetric transmitter (Data Sciences International) was inserted subcutaneously and its leads implanted over the dura above the frontal cortex (1.7 mm anterior to bregma) and the cerebellum (6.4 mm posterior to bregma). Animals recovered from surgery for 7 d before recordings.