Figure 2

Methodology of trial types and experimental timeline. (A) Unexpected object-place-context task. Upper: ‘Contexts’ were comprised of tone-floor pairings. Typical trials: 2 exposure phases (far and middle left; letters denote objects). The test can be made in the 1st context (right-middle) or in the 2nd context (far-right). Exposure and test phases were 2 min, as were the interval between them and the next trial starting in a session. Lower: Example probe trial (test in the 1st context): Floors are replaced (right-middle; tones remain stable) or tones are replaced (far-right; floors remain stable). (B) Discrimination ratio 2 (D2) calculation (context example). For each animal, the context D2 score, recency D2 score and side bias was calculated individually for each trial and then averaged across all trials (in a given session/block) and finally across animals to give an average D2 score. We also separated trials occurring before/after probe trials for a given session, and averaged them across a block, creating a before/after probes context and recency average D2 score. This was sometimes separated further by considering the trials only when test was made in the 1st context or only when test was made 2nd context. (C) Timeline of the main experimental blocks. Upper: Each block had 3 sessions composed of 6 trials (1 probe per session; the location of which is indicated by the purple square). There were 3 blocks and finally one session where all 6 trials were probe trials (not shown in C). We included 1 control probe within each block, where at test there were 2 novel objects present (not previously seen during exposure phases). Block 3 was a within-subject counterbalanced repeat of block 1. Lower: In block 1 and 3 the tonal cue played immediately to the onset of the door opening starting a given exposure/test phase. However, in block 2 we delayed the onset of the tone by 0.5 min, this was relative to the door opening and rats shuttling into the open field chamber of only exposure phases of typical trials.