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Reactivation of latent working memories with transcranial magnetic stimulation

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Science  02 Dec 2016:
Vol. 354, Issue 6316, pp. 1136-1139
DOI: 10.1126/science.aah7011
  • Fig. 1 General procedure.

    (A) In phase 1, functional magnetic resonance imaging (fMRI) data were acquired while participants performed a one-item delayed-recognition task for words, faces, or directions of motion; these data were used for multivariate pattern analysis (MVPA). (B) Classifiers trained on the delay period were used for subsequent analyses. For experiment 1, these classifiers were used to decode fMRI activity from phase 2 (Fig. 2). (C and D) For experiments 2 and 3, they were used in a whole-brain searchlight conjunction analysis to generate participant-specific maps of category-sensitive areas (C); nonoverlapping areas were used for transcranial magnetic stimulation (TMS) targeting in phase 2 (D). (E) In phase 2, single pulses of TMS were delivered during the postcue delay periods.

  • Fig. 2 Experiment 1 fMRI decoding (train phase 1, test phase 2): Classifier evidence as a function of an item’s status, collapsed across stimulus category.

    After stimulus presentation (red and blue circles), delay-period classifier evidence for both items was elevated relative to the empirical baseline of evidence for the category that was not presented on that trial (“absent,” gray). Upon presentation of the first cue (red triangle), evidence for the cued category (red) remained elevated, but for the uncued category (blue) dropped to baseline. (A) After the first probe (red square), on half the trials the second cue designated that the same item would be tested by the second probe, and evidence for the two categories remained the same relative to baseline. (B) When the second cue designated the previously uncued item, evidence for the two categories reversed for the remainder of the trial. Color-coded small squares at the top of each plot indicate P < 0.01; line width reflects SEM.

  • Fig. 3 Experiment 2 EEG decoding (train and test on phase 2 data): Classifier accuracy (area under curve, AUC) as a function of an item’s status at the time of the first cue, collapsed across stimulus category.

    AUC reflects classifier sensitivity to discriminating between evidence for the AMI or UMI relative to the absent category. (A) Classification time series of the AMI and UMI upon stimulus presentation (red and blue circles), the first cue (red triangle), TMS, and first probe (red rectangle), averaged over N = 18 sessions, 2952 trials (decoding ends where the AMI and UMI switched on 50% of the trials). (B) Decoding UMIs as a function of whether TMS targeted that item’s phase 1–defined region or a different category’s region. Color-coded small squares at the top of each plot indicate P < 0.05; line width reflects SEM.

  • Fig. 4 Results from experiments 3 and 4.

    (A) The MVPA-defined TMS target for experiments 3 and 4 (right precuneus). A, anterior; L, left; R, right; P, posterior. (B) Classification time series from experiment 3 showing TMS reactivation of the UMI after the first cue, when the UMI was still relevant (left), but not after the second cue, when the UMI was no longer relevant on the trial (right) averaged over 1152 trials. Color-coded small squares at the top of each plot indicate P < 0.05; line width reflects SEM. (C) Experiment 4 recognition memory for AMI match probes (AMIm), AMI nonmatch probes (AMInm), and UMI (nonmatch) probes. *P < = 0.01; error bars denote SEM.

Supplementary Materials

  • Reactivation of latent working memories with transcranial magnetic stimulation

    Nathan S. Rose, Joshua J. LaRocque, Adam C. Riggall, Olivia Gosseries, Michael J. Starrett, Emma E. Meyering, Bradley R. Postle

    Materials/Methods, Supplementary Text, Tables, Figures, and/or References

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    • Materials and Methods
    • Supplementary Text
    • Figs. S1 to S6
    • Table S1
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    Images, Video, and Other Media

    Movie S1
    Real Faraday rotation of 16 QL Bi2Se3/MoO3 sample at 4.5 K with increasing magnetic fields.

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