Figure 2.

Animals exhibit distinct palatability (behavioral) responses that depend on the presence of auditory cue(s). (A) The lick rates (licks/s) for the three brief-access tests aligned to the RS (vertical dashed line) as a function of sucrose concentration. The licking responses are shown for the “Total” trials (upper), for Complete (middle) and Incomplete trials (bottom panels). The n's are the number of trials pooling across animals and sessions. Only the Total and Incomplete trials significantly discriminate among the sucrose concentrations. The arrow in the PSTHs of the Start test highlights the abrupt decrease in lick rate for all tastants after which the lick rate tracks the sucrose concentration. The arrow just after RE in the Start/Stop test indicates that animals rapidly stopped licking. Also shown is the Pearson's correlation (r's) between the lick rate in the Reward epoch and the sucrose concentrations. (B) Cumulative distribution functions (CDFs) for the lick rate (total number of licks during the entire 5 s Reward epoch). (C) The CDFs of the first bout duration over the range of RS for the three tests. The bold horizontal lines at 0.5 on the Y-axis indicate the median bout duration for each sucrose concentration. Note that the first lick bout duration was largest in the Start/Stop test and it was the most positively correlated with sucrose concentrations (see r's). The small arrows in the CDF's indicate the fraction of trials where animals made their first lick bout with a one-lick (bout durations equal 0 s).