Article Figures & Data
Figures
- Figure 1.
An overview of the source memory AB/AC paradigm and approach to using MVPA to measure memory reactivation in the current experiment. A, Participants studied words while performing one of four encoding tasks. Words in the AB (blue boxes) and AC trials (green boxes) were presented twice in two different encoding tasks, whereas words for DE trials (red boxes) and filler trials were presented in a single encoding task. During retrieval, participants first made an old/new decision about the word, and for words receiving an “old” response, they were asked to retrieve all of the encoding tasks performed on the word. B, A multivariate classifier was trained to discriminate the four encoding tasks using the DE trials and tested on the AB and AC trials to measure task evidence at encoding (i.e., classifier evidence for the AB encoding task during the AB trial) and task reactivation (i.e., classifier evidence for the AB encoding task during the AC trial sharing the same word), respectively. C, Pattern similarity analysis was used to measure item reactivation by correlating the neural patterns elicited by AB and AC trials sharing the same word and subtracting the average correlation between AC and AB trials with different words that shared the same AB encoding task.
- Figure 2.
The 1000 voxel feature set used for the multivariate classification and pattern-similarity MPVA. The 250 task-selective voxels for each encoding task are shown in different colors and overlaid on the across-participant average T1-weighted structural scan in MNI space. The axial slices depicted are spaced every 6 mm with the most inferior (top left) and superior (bottom right) corresponding to z = −27 and z = 57, respectively.
- Figure 3.
Source memory accuracy calculated from the behavioral data. A, Source accuracy for the DE, AB, and AC encoding tasks. Note that in this panel, AB source accuracy was calculated ignoring AC source memory and vice versa. B, Source accuracy for the AB encoding task conditional on whether the AC encoding task was remembered (hit) or forgotten (miss). C, Source accuracy for the AC encoding task conditional on whether the AB encoding task was remembered or forgotten. Error bars represent ±1 SEM.
- Figure 4.
A–D, Results from the subsequent source memory analysis of the four MVPA measures: task reactivation (A), item reactivation (B), AB task evidence at encoding (C), and AC task evidence at encoding (D). Each panel depicts the across-participant average of the relevant MVPA metric for the four cells formed by treating subsequent source memory for the AB and AC encoding tasks as separate factors. Error bars represent ±1 SEM.
Tables
- Table 1.
Source accuracy as a function of item type and the ITIs of the preceding trial (top) and following a trial (bottom)
Item type DE AB AC Preceding ITI 4 s 0.75 (0.03) 0.53 (0.03) 0.60 (0.02) 6 s 0.79 (0.03) 0.51 (0.04) 0.56 (0.04) 8 s 0.76 (0.06) 0.50 (0.05) 0.56 (0.05) Following ITI 4 s 0.75 (0.03) 0.53 (0.03) 0.60 (0.03) 6 s 0.82 (0.03) 0.51 (0.04) 0.58 (0.04) 8 s 0.73 (0.04) 0.54 (0.05) 0.58 (0.04) SEs are provided in parentheses.
Classifier 1 Classifier 2 Classifier 3 Classifier 4 Encoding task Artist 0.53 (0.04) 0.52 (0.04) 0.54 (0.04) Function 0.59 (0.04) 0.57 (0.04) 0.59 (0.04) Pleasantness 0.53 (0.03) 0.49 (0.03) 0.54 (0.03) Vacation 0.61 (0.04) 0.55 (0.04) 0.57 (0.03) Values in parentheses reflect ±1 SEM. Chance performance for was 33.33%. Classifier accuracy was collapsed across each fold of the fivefold approach. The tasks discriminated by the classifiers were as follows: Classifier 1, Artist versus Function versus Vacation; Classifier 2, Artist versus Function versus Pleasantness; Classifier 3, Artist versus Pleasantness versus Vacation; Classifier 4, Function versus Pleasantness versus Vacation.
