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. 2022 Apr 29;20(4):e3001338. doi: 10.1371/journal.pbio.3001338

Fig 1. Schematic of the behavioral task and results.

Fig 1

(A) Mice were trained in a head-fixed biconditional discrimination task where they learned to discriminate between different pairings of “context” and “target” cues. Mice were first presented with the context cue (1 s), followed by a delay (2 s), followed by target cue presentation (1 s), and an additional response period (1 s). Whether a target cue was rewarded depended upon the identity of the preceding context cue. For instance, licking in response to O3 was rewarded when preceded by O1, but not O2, while for O4 was rewarded when preceded by O2, but not O1. Note, this means that by design, each context cue was rewarded on half of the trials it was presented on. (B) Trial structure of the task. Purple arrows indicate trials with context cue 1 (O1); orange arrows indicate trials with context cue 2 (O2). Dark arrows after context cue presentation indicate rewarded trials; light arrows indicate unrewarded trials. This color scheme is used throughout the text. (C) Example learning curve showing proportion of trials with a lick over the course of full-task training. Data are shown for each trial type, in 20 trial blocks, with gaps separating individual training sessions. This learning curve shows that by day 6 (around trial 400), there was a clear difference in responding to rewarded versus unrewarded trials. (D) Number of training sessions before each mouse reached the criterion of 3 consecutive sessions with >80% correct responding, after which recordings began. (E) Behavioral performance during recording sessions showing the average proportion of trials with a licking response during the ITI, context cue period, delay period, and target cue period for each trial type for each mouse, demonstrating that mice discriminated between rewarded (green) and unrewarded trial types (red). Asterisks denote significant differences (p < 0.05 based on a bootstrap with trial labels shuffled; see Methods). Data: https://gin.g-node.org/jgmaz/BiconditionalOdor. ITI, intertrial interval.