Figure 6. Ensemble activity showed a comparable level of selectivity for stimulus-environment conjunction during stimulus and non-stimulus periods.

(A) Grayscale plots show the normalized firing rate during six trial blocks (from left, ACS trials in Box 1, ACS-US trials in Box 1, ACS trials in Box 2, ACS-US trials in Box 2, VCS trials in Box 1, and VCS-US trials in Box 1). Cells were sorted based on the ACS-induced firing rate during the ACS-US block in Box 1, from the largest increase (cell #1) to the largest decrease (cell #250). Two white lines indicate the onset and offset of the CS while black bars mask US artifacts. (B) Matrices of the correlation coefficient (r) of ensemble firing rates (State vector, SV) between two of six trial blocks during CS-US pairings (Trial) and intervals between trials (ITI). (C) During both task phases, the r for two blocks with different CS (Modality; mean ± SEM, n = 20 runs with 10 subsampled trials) was comparable to that for two blocks that differed in all task variables (All). It was significantly lower than that in different conditioning boxes (Environment) and with different stimulus contingencies (CS-alone blocks and CS-US blocks, Relationship). The r for Relationship was significantly higher than that for Environment but lower than that for odd- and even-numbered trials from the same block (None). *p<0.001, in posthoc Tukey HSD.

DOI: http://dx.doi.org/10.7554/eLife.28611.013

Figure 6—figure supplement 1. Ensemble firing patterns differentiated trial blocks more strongly depending on the CS modality and conditioning environment than CS-US relationship.

(A) Support Vector Machine (SVM) classifier was applied to binned firing rates during six trial blocks. Representative examples of confusion matrices indicating proportions of trial types that were identified by the SVM classifier correctly (warm colors along the diagonal) or misidentified as a different trial type (lighter colors off-diagonal). During CS-US pairings (trial) and inter-trial intervals (ITI), nearly all misclassifications were due to the confusion between CS-alone trials and CS-US paired trials. (B) Classification accuracy (mean ± SEM, 20 runs with 200 randomly subsampled cells) for binary discrimination along stimulus relationship (CS-alone vs. CS-US trials; Relationship), modality (auditory vs. visual CS trials; Modality), and conditioning environment (Box 1 vs. 2; Environment). In both task phases, the classification accuracy for Modality and Environment was higher than that for Relationship. *p<0.001 in posthoc Tukey HSD.

DOI: http://dx.doi.org/10.7554/eLife.28611.015