After recovery to pre-surgical body weight, mice were food restricted to 85% body weight to increase exploration, habituated to handling and recording in a small, familiar environment, and then in an open field. Three days later, animals were exposed to differential fear conditioning as previously described (Likhtik et al., 2014). Briefly, mice received 5-6 trials each of 8 kHz or white noise tones, counterbalanced and pseudo-randomly presented daily for three days. Each stimulus consisted of 30 pips lasting 50 ms. delivered at 1Hz. One tone type was paired with shock (CS+; 0.4 mA, 1 sec), and the other was explicitly unpaired (CS−).
