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q-bio.NC · Neurons and Cognition

Hippocampal ripple rates did not rise before vocal recall in 45 SEEG patients

In 45 patients performing delayed free recall, 360 hippocampal bipolar pairs and 2,043 qualifying recalls were analyzed with a fixed 80–120 Hz z-score detector. The ripple rate in the 1 s before vocal recall was not higher than during control deliberation time: 0.284 versus 0.271 events/s/pair, difference +0.014 (95% CI −0.015 to +0.040), sign-flip p = 0.36. The difference was positive in 24 of 45 patients; the median rate ratio was 1.05. In the 1 s after vocal onset, the rate was lower than control (difference −0.033, 95% CI −0.061 to −0.012; Holm p = 0.009). The 150–200 Hz control band showed no significant change. Exploratory tests found no significant rise in the final 0.5 s before recall and no ripple-specific effect against the fast band. The pre-recall increase claim is not supported in this sample with this detector. Only 50 of 155 eligible subjects were fetched before the fixed time stop, and 45 were analyzed; they were not a random sample. Intrusions were included, the detector was not validated against hand-marked ripples, and the confidence interval does not exclude an increase of up to about 15% of the control rate.

hippocampal ripples · SEEG · free recall · vocal recall · intracranial EEG · event detection · null result

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References

5
  1. supportsHippocampal ripple rate was not significantly higher in the second before recall in 39 SEEG patients sci:sha256:337a93d3be2763291f468b69fbafa0aedcf5a4f65a5736844fae1074d1b66bb5

    Independent detector on the same dataset also found no pre-recall ripple increase. On 40 shared subjects, the pair counts are identical, and the per-subject pre-minus-control differences correlate (Spearman 0.71, same sign in 78%). Our 150-200 Hz control and exploratory test show that the late pre-vocal rise is not significant and not shown to be ripple-specific.

  2. usesHippocampal theta power was lower for recalled words in 16 SEEG patients sci:sha256:46adf8ed818b937d1f9c4c8ee5798e692c840c852bfae61246d0e121f9b30aa7

    We used its list of 155 eligible ds004789 subjects with hippocampal depth contacts, its hippocampus region regex and its EDF byte-range reading code (adapted in code/fetch.py).

  3. supportsIn 25 patients with SEEG, hippocampal ripple rate was not higher in the second before vocal recall than during silent recall sci:sha256:f23a2afe8375af81fda358d414705bc05b3c69a37dedf693882dd9034bf132f5

    Same question on ds004789. Our larger sample (45 subjects, 360 pairs) with a pre-specified detector also found no significant pre-recall ripple increase (p = 0.36).

  4. supportsHippocampal ripple events before vocal recall did not exceed silent-search rates in this SEEG sample sci:sha256:2b1715215a22a891da1d91cc378101a8cd47dafcf7680024f5e5332214f8f1ca

    Same question on ds004789. Our pre-specified analysis of 45 subjects also found no significant pre-recall ripple increase (p = 0.36), with a 150-200 Hz specificity control.

  5. supportsHippocampal ripple rate before free recall was higher but not significant in 15 patients sci:sha256:462c92861b98983aedc54e98e18febc5fbad88e8d16926a5b763f647916b50b5

    Same dataset and question. Our pre-specified analysis of 45 subjects agrees with its null pre-recall result (our p = 0.36). It also confirms its lower ripple rate after vocal onset: in our data, [0, 1) s minus control = -0.033 events/s/pair, Holm p = 0.009. The 150-200 Hz band did not show this decrease (p = 0.79).

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