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. 2018 Jun 5;7:e34467. doi: 10.7554/eLife.34467

Figure 5. Comparing HMM congruence and Bayesian decoding in replay detection.

(a) Eight examples from one session show that Bayesian decoding and HMM model-congruence can differ in labeling of significant replay events. For each event, spike rasters (ordered by the location of each neuron’s place field) and the Bayesian decoded trajectory are shown. ‘+' (‘-') label corresponds to significant (insignificant) events. (left) Both methods can fail to label events that appear to be sequential as replay and (right) label events replay that appear non-sequential. (b) We recruited human scorers to visually inspect Bayesian decoded spike trains and identify putative sequential replay events. Using their identifications as labels, we can define an ROC curve for both Bayesian and HMM model-congruence which shows how detection performance changes as the significance threshold is varied. (inset) Human scorers identify 24% of PBEs as replay. Setting thresholds to match this value results in agreement of 70% between Bayesian and HMM model-congruence. (c) Using the same thresholds, we find 70% agreement between algorithmic and human replay identification. (All comparison matrices, p<0.001, Fisher’s exact test two-tailed.).

Figure 5.

Figure 5—figure supplement 1. Human scoring of PBEs and session quality.

Figure 5—figure supplement 1.

(a) Manual scoring results from eight human scorers (six individuals scored n=1883 events, two individuals scored a subset of n=1423 events). Events were presented to each participant in a randomized order, and individuals were allowed to go back to modify their results before submission. Here, events are ordered according to individual #8’s classifications. (b) The model-congruence (HMM) approach appearsto have higher accuracy when the session quality is higher (R2=0.17, F=2.9), which is consistent with our expectation that we need many congruent events in the training set in order to learn a consistent and meaningful model. (c) The session quality is strongly correlated with the number of PBEs recorded within a session (R2=0.96, F=392.6).