Licking microstructure

To quantify reward ‘liking’, immediately after each PIT test, rats were given an opportunity to lick, non-contingently, from a spout in the operant chamber delivering 50% SCM for 5 min in order to assess their licking microstructure. A contact lickometer (Med Associates, VT) was used to measure individual licking responses. The program timer controlling session length did not begin until each rat initiated licking, allowing a full 5 min of access from when the spout was first licked. All licks were recorded and parsed into bouts, defined as any continuous series of licks separated by less than 1 sec [65].