Epileptic High-Frequency Oscillations in Intracranial EEG Are Not Confounded by Cognitive Tasks
Rationale: High-frequency oscillations (HFOs) in intracranial EEG (iEEG) are used to delineate the epileptogenic zone during presurgical diagnostic assessment in patients with epilepsy. HFOs are historically divided into ripples (80–250 Hz), fast ripples (FR, >250 Hz), and their co-occurrence...
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| Format: | Article |
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Frontiers Media S.A.
2021-02-01
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| Series: | Frontiers in Human Neuroscience |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/fnhum.2021.613125/full |
| _version_ | 1818649173914812416 |
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| author | Ece Boran Lennart Stieglitz Johannes Sarnthein Johannes Sarnthein |
| author_facet | Ece Boran Lennart Stieglitz Johannes Sarnthein Johannes Sarnthein |
| author_sort | Ece Boran |
| collection | DOAJ |
| description | Rationale: High-frequency oscillations (HFOs) in intracranial EEG (iEEG) are used to delineate the epileptogenic zone during presurgical diagnostic assessment in patients with epilepsy. HFOs are historically divided into ripples (80–250 Hz), fast ripples (FR, >250 Hz), and their co-occurrence (FRandR). In a previous study, we had validated the rate of FRandRs during deep sleep to predict seizure outcome. Here, we ask whether epileptic FRandRs might be confounded by physiological FRandRs that are unrelated to epilepsy.Methods: We recorded iEEG in the medial temporal lobe MTL (hippocampus, entorhinal cortex, and amygdala) in 17 patients while they performed cognitive tasks. The three cognitive tasks addressed verbal working memory, visual working memory, and emotional processing. In our previous studies, these tasks activated the MTL. We re-analyzed the data of these studies with the automated detector that focuses on the co-occurrence of ripples and FRs (FRandR).Results: For each task, we identified those channels in which the HFO rate was modulated during the task condition compared to the control condition. However, the number of these channels did not exceed the chance level. Interestingly, even during wakefulness, the HFO rate was higher for channels within the seizure onset zone (SOZ) than for channels outside the SOZ.Conclusion: Our prospective definition of an epileptic HFO, the FRandR, is not confounded by physiological HFOs that might be elicited by our cognitive tasks. This is reassuring for the clinical use of FRandR as a biomarker of the EZ. |
| first_indexed | 2024-12-17T01:30:07Z |
| format | Article |
| id | doaj.art-fd9d5834e7c74a089b98bc69ff703a4e |
| institution | Directory Open Access Journal |
| issn | 1662-5161 |
| language | English |
| last_indexed | 2024-12-17T01:30:07Z |
| publishDate | 2021-02-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Human Neuroscience |
| spelling | doaj.art-fd9d5834e7c74a089b98bc69ff703a4e2022-12-21T22:08:36ZengFrontiers Media S.A.Frontiers in Human Neuroscience1662-51612021-02-011510.3389/fnhum.2021.613125613125Epileptic High-Frequency Oscillations in Intracranial EEG Are Not Confounded by Cognitive TasksEce Boran0Lennart Stieglitz1Johannes Sarnthein2Johannes Sarnthein3Klinik für Neurochirurgie, Universitäts Spital und Universität Zürich, Zurich, SwitzerlandKlinik für Neurochirurgie, Universitäts Spital und Universität Zürich, Zurich, SwitzerlandKlinik für Neurochirurgie, Universitäts Spital und Universität Zürich, Zurich, SwitzerlandNeuroscience Center Zurich, University of Zurich and ETH Zurich, Zurich, SwitzerlandRationale: High-frequency oscillations (HFOs) in intracranial EEG (iEEG) are used to delineate the epileptogenic zone during presurgical diagnostic assessment in patients with epilepsy. HFOs are historically divided into ripples (80–250 Hz), fast ripples (FR, >250 Hz), and their co-occurrence (FRandR). In a previous study, we had validated the rate of FRandRs during deep sleep to predict seizure outcome. Here, we ask whether epileptic FRandRs might be confounded by physiological FRandRs that are unrelated to epilepsy.Methods: We recorded iEEG in the medial temporal lobe MTL (hippocampus, entorhinal cortex, and amygdala) in 17 patients while they performed cognitive tasks. The three cognitive tasks addressed verbal working memory, visual working memory, and emotional processing. In our previous studies, these tasks activated the MTL. We re-analyzed the data of these studies with the automated detector that focuses on the co-occurrence of ripples and FRs (FRandR).Results: For each task, we identified those channels in which the HFO rate was modulated during the task condition compared to the control condition. However, the number of these channels did not exceed the chance level. Interestingly, even during wakefulness, the HFO rate was higher for channels within the seizure onset zone (SOZ) than for channels outside the SOZ.Conclusion: Our prospective definition of an epileptic HFO, the FRandR, is not confounded by physiological HFOs that might be elicited by our cognitive tasks. This is reassuring for the clinical use of FRandR as a biomarker of the EZ.https://www.frontiersin.org/articles/10.3389/fnhum.2021.613125/fullepilepsy surgeryseizure onset zoneepileptogenic zonemedial temporal lobeworking memoryemotional processing |
| spellingShingle | Ece Boran Lennart Stieglitz Johannes Sarnthein Johannes Sarnthein Epileptic High-Frequency Oscillations in Intracranial EEG Are Not Confounded by Cognitive Tasks Frontiers in Human Neuroscience epilepsy surgery seizure onset zone epileptogenic zone medial temporal lobe working memory emotional processing |
| title | Epileptic High-Frequency Oscillations in Intracranial EEG Are Not Confounded by Cognitive Tasks |
| title_full | Epileptic High-Frequency Oscillations in Intracranial EEG Are Not Confounded by Cognitive Tasks |
| title_fullStr | Epileptic High-Frequency Oscillations in Intracranial EEG Are Not Confounded by Cognitive Tasks |
| title_full_unstemmed | Epileptic High-Frequency Oscillations in Intracranial EEG Are Not Confounded by Cognitive Tasks |
| title_short | Epileptic High-Frequency Oscillations in Intracranial EEG Are Not Confounded by Cognitive Tasks |
| title_sort | epileptic high frequency oscillations in intracranial eeg are not confounded by cognitive tasks |
| topic | epilepsy surgery seizure onset zone epileptogenic zone medial temporal lobe working memory emotional processing |
| url | https://www.frontiersin.org/articles/10.3389/fnhum.2021.613125/full |
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