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Eight SEEG pairs showed no clear gain over fixation for letter load across sessions in 15 patients under assumed epoch timing

We tested whether a small SEEG readout predicts letter load in a later session. We used the first and last numbered session from each of 15 patients in OpenNeuro ds004752 version 1.0.1. We assumed that the public epoch starts at fixation and that session numbers give session order. Training used the first session. Testing used the last session. The model used eight adjacent depth-contact pairs and fixed power features. It predicted 4 letters versus 6 or 8 letters. The main test used 683 training trials and 703 test trials with the source clean flag. Mean patient balanced accuracy was 54.3% for delay change and 51.3% for fixation. The gain was 3.0 percentage points. Its 95% patient bootstrap interval was -0.9 to 6.9 points. The two-sided patient sign-flip p value was 0.165. Thus, this test showed no clear gain over fixation. It did not show that the true gain is zero. A model with trial history alone reached 55.2%. Delay accuracy was 52.4% when source flagged trials were included. The task made low-load trials more likely after errors. A session label shuffle does not preserve this rule and gives no valid task randomization test. The package has source records, retrieval code, features, models, predictions, figures, and checks. A full analysis rerun gave identical result files. One complete source hash was checked. The other 29 sources have S3 version and range-hash records. These findings apply to this offline task test. They do not establish a useful live BCI signal or a benefit from stimulation.

SEEG · verbal working memory · letter load · balanced accuracy · brain-computer interface · cross-session decoding

Admitted 9 citing publications

References

4
  1. usesdoi:10.18112/openneuro.ds004752.v1.0.1

    The analysis used OpenNeuro ds004752 version 1.0.1; its saved version-specific metadata declares CC0.

  2. supportsdoi:10.7554/eLife.78677

    The source task paper supplies the task timing and error-to-low-load rule used to define and assess the analysis windows and history checks.

  3. doi:10.1126/sciadv.aav3687
  4. doi:10.1038/s41597-020-0364-3

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