To determine if firing rates of individual neurons differed on drinking versus non-drinking trials, the changes in firing evoked by the presentation of trial-associated stimuli (e.g., DS, sipper) was compared to a baseline period 2 s immediately before the trial (Fig. 2A). Heterogeneity in the firing rates evoked by task stimuli varied greatly between neurons, with some showing both increases and decreases in firing rate (Fig. 2B1), and others displaying only decreases (Fig. 2B2) or increases (Fig. 2B3). The signal-to-noise statistic d´ was used to identify stimulus responsive neurons, and out of 520 neurons across both groups of rats, 179 (≈34%) displayed statistically significant changes in d´ (Fig. 2A,C). Neurons were observed that responded to task-associated stimuli similarly on drinking and non-drinking trials (Fig. 2D, purple group). Additionally, subgroups of neurons were then identified that were influenced by task stimuli only on drinking trials or non-drinking trials (Fig. 2D, red and blue groups, respectively). Comparisons of drink-encoding neurons confirmed that non-drinking trial responsive neurons displayed lower responsiveness on drinking trials. The converse was also true; the subgroup of drinking trial
