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q-bio.NC · Neurons and Cognition

FR2 session 0 showed no group-level encoding SME in 24 subjects, but low power did not exclude small effects

We tested whether the encoding subsequent memory effect (SME) reported for RAM FR1 occurred in non-stimulation word lists from RAM FR2 session 0 in OpenNeuro ds005489. We analyzed SEEG bipolar pairs for words from lists with stim_list = 0, using epochs from sample/fs to 1.6 s. For each subject, we z-scored log band power per pair over words, calculated Welch t statistics for recalled versus not recalled words per pair, and averaged across pairs. Of 38 dataset subjects, 32 had session 0 SEEG data and 24 met the requirement of at least 10 recalled and 10 not-recalled words; median words per included subject was 60. A two-sided sign-flip test with 20,000 flips found no group effect in the three primary features: theta (3–8 Hz), mean subject t = -0.131, p = 0.295, Holm p = 0.886; high-frequency activity (HFA, 70–150 Hz), mean t = -0.043, p = 0.683, Holm p = 1.0; and tilt (zHFA − ztheta), mean t = +0.075, p = 0.567, Holm p = 1.0. The 95% bootstrap confidence intervals included zero and small effects in the predicted direction. The test had low power because each session 0 contained five or fewer non-stimulation lists (60 words or fewer), and stimulation carry-over is possible because these lists occurred between stimulation lists. The null result does not show that the SME is absent in FR2. Theta and beta signs agreed with the FR1 prediction but were not significant. R1048E had a 256 Hz sampling rate, so its HFA range was 70–128 Hz. The plan was written and hashed before any EEG signal was read.

subsequent memory effect · intracranial EEG · free recall · RAM FR2 · SEEG · theta · high-frequency activity · power analysis

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References

7
  1. supportsThe 70–150 Hz subsequent memory effect was not detected in five catFR3 SEEG subjects on non-stimulation lists sci:sha256:7dcf184fb6bc8fa01ab7715dbe2e5d7d883624e8975ebc61c6c4cb8a5691ce31

    This null agrees with the earlier null HFA SME in a RAM stimulation dataset (catFR3), now in FR2 non-stimulation lists with more subjects.

  2. usesIn 71 completed OpenNeuro iEEG datasets, 42 contained SEEG channels across 1,167 subjects sci:sha256:79a420e35329acba12ac65e4e29aee4286ecfce55fed09cf0b4967a9658202a9

    The ds005489 census was used to plan subject selection.

  3. usesIn 28 patients, open-loop SEEG stimulation at encoding was associated with 2-point lower recall of stimulated words and no impairment above 5 points sci:sha256:ed3152e6018f151b69770c848513cde2fa573f1485fc42fae7f0244cc8317e65

    This work uses the FR2 non-stimulation lists that the stimulation-effect studies use as the baseline condition.

  4. usesEvent onset differs from sample-based time in 538 of 554 files across nine RAM-family iEEG datasets sci:sha256:bb1c5599a4dabaae2ebb21b53654012eb403c29b4849022010df0dd0b7490170

    Epoch timing uses the RAM rule sample/fs, not the events onset column.

  5. usesAssuming sample/fs marks EDF time, 21 pure-SEEG FR1 patients showed a subsequent memory effect hidden by onset timing sci:sha256:799055dd0e8b95498bb3ea5d9564670cf779d6970c9993bda2f0c41150b419e7

    The FR1 SME method and prediction (theta down, HFA up, tilt up) are tested again in FR2 non-stimulation lists.

  6. usesWith sample/fs epoch timing, the catFR1 null of 63055d12 changes to a subsequent memory effect (tilt +0.56, Holm p 0.0006) in 23 SEEG patients of ds004809, session 0 sci:sha256:f76bfd58d757a861b47c8d6b5ccc0494949caa735473fdc78db58946eb3a7cd5

    The feature and analysis code structure was adapted from this sample/fs-timed SME package.

  7. usesdoi:10.18112/openneuro.ds005489.v1.0.3

    The analysis used RAM FR2 session 0 data from OpenNeuro ds005489 version 1.0.3.

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