Knowledge Vault 3/92 - G.TEC BCI & Neurotechnology Spring School 2024 - Day 10
ECS-based neuromodulation with HGA-dynamics in neurosurgery
Kyousuke Kamada, Mengumino Hospital (JP)
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Concept Graph & Resume using Claude 3 Opus | Chat GPT4 | Llama 3:

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gamma at new hospital. 1] A --> C[EEG, electrocortical stimulation for
seizures, mapping: risks. 2] A --> D[Dr. Kamada & G.Tec: real-time
mapping via ECoG. 3] A --> E[Arterial spin labeling MRI
visualizes seizure foci. 4] A --> F[High gamma mapping motivates
patients, real-time activation. 5] F --> G[Dr. Kamada studies high
gamma dynamics, spread. 6] F --> H[Passive high gamma mapping:
sensitive language mapping. 7] H --> I[Covert speech: high gamma spreads
occipital to frontal. 8] F --> J[High gamma for pre-surgical,
intraoperative mapping. 9] J --> K[High gamma guides focused
electrical stimulation. 10] J --> L[Stimulation & high gamma have
similar sensitivity, specificity. 11] F --> M[Passive story listening & CCEPs
map language under anesthesia. 12] M --> N[Stimulating temporal areas elicits
frontal language CCEPs. 13] M --> O[Passive mapping & CCEPs: language
mapping in <3 min. 14] O --> P[DTI visualizes connections,
complements CCEPs. 15] A --> Q[Corpus callosotomy disconnects
seizure spread. 16] Q --> R[Callosum stimulation elicits contralateral
CCEPs, cut eliminates. 17] Q --> S[Anterior callosotomy alone can
eliminate seizures. 18] Q --> T[Post-callosotomy: transient aphasia,
long-term seizure freedom. 19] Q --> U[Post-callosotomy: previously ineffective
medications may work. 20] Q --> V[Anterior callosum: more glia,
relates to seizure role. 21] Q --> W[Bilateral ECoG & midline callosotomy:
safe, precise disconnection. 22] A --> X[Short-term stimulation interrupts
speech at critical times. 23] X --> Y[Critical speech interruption window
matches high gamma peak. 24] X --> Z[Precisely-timed stimulation could
briefly interrupt function. 25] A --> AA[Real-time ECoG, CCEPs improve
surgical precision. 26] B --> AB[Dr. Kamada invites collaboration
at Hokkaido hospital. 27] A --> AC[Adoption obstacles: interdisciplinary
background needed. 28] A --> AD[Adoption obstacles in Japan:
limited ECoG availability. 29] Q --> AE[Anterior callosotomy: safe, effective
for seizures under 25. 30] class A,B,AB,AC,AD kamada; class C,D eeg; class E,F,G,H,I,J,K,L,X,Y,Z gamma; class M,N,O,P,AA mapping; class Q,R,S,T,U,V,W,AE callosotomy; class C,K,L,X,Y,Z stimulation;


1.- Dr. Kyousuke Kamada discussed his recent research on high gamma accumulation and dynamics at his new hospital in Chitose, Hokkaido, Japan.

2.- EEG monitoring and electrocortical stimulation are routine for seizure diagnosis and functional mapping, but risk evoking seizures, especially in motor cortex.

3.- Dr. Kamada collaborates with G.Tec to establish real-time functional mapping by recording ECoG to avoid stimulating the brain and causing seizures.

4.- Arterial spin labeling MRI can visualize increased blood flow around seizure foci, complementing neurophysiology, the gold standard for seizure diagnosis.

5.- High gamma mapping allows patients to see activation in real-time, motivating them to perform language and motor tasks well.

6.- Dr. Kamada is interested in the dynamics of high gamma activity over time and how it spreads between brain regions.

7.- Passive high gamma mapping during story listening has high sensitivity and specificity for language mapping without patient cooperation or seizure risk.

8.- Covert speech elicits high gamma activation spreading from occipital to frontal language areas, demonstrating spatiotemporal dynamics of language processing.

9.- High gamma mapping is useful for pre-surgical planning and intraoperative mapping during awake craniotomies to guide electrical stimulation testing.

10.- High gamma mapping has high concordance with electrical stimulation for identifying motor and language areas, allowing more focused stimulation.

11.- Electrical stimulation and high gamma mapping have different mechanisms but similar sensitivity and specificity for functional mapping.

12.- Combining passive story listening and cortico-cortical evoked potentials (CCEPs) allows quick language mapping even in uncooperative patients under anesthesia.

13.- Stimulating temporal language areas elicits CCEPs in frontal language areas, demonstrating functional connectivity that can guide surgical resection.

14.- Using passive mapping and CCEPs, language mapping can be done in under 3 minutes without patient cooperation or seizure risk.

15.- Visualizing white matter connections between temporal and frontal language areas using diffusion tensor imaging complements CCEP mapping of functional connectivity.

16.- Corpus callosotomy disconnects seizure spread between hemispheres as a treatment for severe, drug-resistant epilepsy with drop attacks.

17.- Corpus callosum stimulation elicits contralateral CCEPs, indicating functional connectivity that is eliminated immediately when the callosum is cut.

18.- Anterior corpus callosotomy alone can eliminate seizures, as demonstrated by abolition of contralateral CCEPs when the anterior callosum is cut.

19.- Post-callosotomy, patients may be transiently aphasic but typically recover language in 1-3 days, and seizure freedom can last years.

20.- If seizures recur after callosotomy, medications that were previously ineffective may work, suggesting a "neuromodulation" effect of callosotomy.

21.- The anterior corpus callosum contains more glial cells than posterior regions, possibly relating to its key role in seizure spread.

22.- Bilateral ECoG and midline corpus callosotomy allows safe, precise disconnection of seizure spread based on CCEP mapping.

23.- Short-term electrical stimulation at specific times during picture naming can interrupt speech, indicating critical periods for language production.

24.- The critical time window for interrupting speech by stimulation corresponds to the peak of high gamma activation in language cortex.

25.- Precisely-timed stimulation based on high gamma dynamics could allow very brief interruption of language and motor function during mapping.

26.- Real-time visualization of ECoG signals and CCEPs should contribute to improving neurosurgical precision for epilepsy and brain tumor surgery.

27.- Dr. Kamada invites collaboration and visits to his hospital in Hokkaido to treat more epilepsy surgery patients using these techniques.

28.- Main obstacles to wider adoption include need for strong interdisciplinary background in neurosurgery, electrophysiology, and engineering.

29.- Another obstacle is limited availability of ECoG electrodes in Japan; Dr. Kamada currently uses the Nihon Kohden system but is transitioning to G.Tec.

30.- Anterior corpus callosotomy is generally safe and effective for controlling seizures in patients under age 25, with empirically low risk of permanent deficits.

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