The End Of Knowledge - Vault 3 - G.TEC BCI & Neurotechnology Spring School 2024 - Day 10

graph LR classDef dr fill:#f9d4d4, font-weight:bold, font-size:14px; classDef ecogtec fill:#d4f9d4, font-weight:bold, font-size:14px; classDef highgamma fill:#d4d4f9, font-weight:bold, font-size:14px; classDef ecs fill:#f9f9d4, font-weight:bold, font-size:14px; classDef research fill:#f9d4f9, font-weight:bold, font-size:14px; A[Takahiro Sanada] --> B[neurosurgeon, Hokkaido. 1] A --> C[G.Tec: BCI research,
hardware, sales worldwide. 2] C --> D[Invasive BCI enables novel projects. 3] A --> E[ECoG in surgery: strips, grids,
and amplifier for high gamma. 4] A --> F[Neuromodulation: measuring and stimulating
brain regions based on activity. 5] A --> G[Pfurtscheller: event-related desynchronization
during imagined movement. 6] A --> H[Implants need precise
electrode placement. 7] H --> I[Miller: 64 ECoG
channels in epilepsy patient. 8] H --> J[High gamma localized,
diminishes with repetition. 9] E --> K[ECoG grids: platinum,
single-use, 64 channels. 10] C --> L[Early ECoG BCI: cursor
control, DOOM. Schalk. 11] L --> M[US Army impressed,
funds ECoG research. 12] E --> N[Japan 2011: real-time
ECoG for gesture classification. 13] N --> O[Telepresence: patient controls
1M robot via ECoG. 14] E --> P[c-VEP avoids seizures in
SSVEP with epilepsy patients. 15] C --> Q[Siegfried BCI: rapid cortical
mapping during tasks. 16] H --> R[Miller: decoding temporal dynamics
of high gamma in gestures. 17] A --> S[ECS: clinical standard for
mapping, but has limitations. 18] S --> T[ECS: manual, time-consuming,
seizure risk, lower resolution. 19] S --> U[High gamma mapping superior
to ECS in many ways. 20] E --> V[High gamma mapping visualizes
seizures to guide surgery. 21] E --> W[Paradigms: rest, Rubik's cube, tongue,
story listening, etc. 22] E --> X[High gamma corresponds to BOLD
fMRI for sensorimotor mapping. 23] E --> Y[Picture naming: visual->language
areas activate sequentially. 24] E --> Z[High gamma mapping is
consistent and matches ECS. 25] C --> AA[Cortec-U used worldwide for
clinical high gamma mapping. 26] H --> AB[Ince: micro-ECoG detects
ultra-high gamma to 1 kHz. 27] E --> AC[CCEPs map networks by
stimulating and recording. 28] H --> AD[High-res ECoG maps
individual finger representations. 29] E --> AE[SSEP quickly identifies
central sulcus. 30] E --> AF[ECoG BCI enables prosthetic
hand control, embodiment. 31] class A,B dr; class C,D,L,M,Q,AA ecogtec; class E,F,H,I,J,K,N,O,R,U,V,W,X,Y,Z,AB,AC,AD,AE,AF highgamma; class G,S,T ecs; class P research;

Resume:

1.- Dr. Takahiro Sanada is a neurosurgeon at Asahikawa Medical University in Hokkaido, Japan, located 5 hours from Sapporo by train.

2.- Dr. Sanada discusses high gamma activity mapping in neurosurgery, using examples from his own research and clinical work.

3.- Electrocortical stimulation (ECS) mapping is a classic but subjective method to identify functional brain areas during awake brain surgery.

4.- ECS was used to map language areas in a patient with a left temporal brain tumor prior to resection.

5.- High gamma activity mapping using ECoG is an objective, quantitative alternative to ECS that doesn't require direct brain stimulation.

6.- Dr. Sanada's group uses G.Tec equipment to measure ECoG and analyze high gamma activity in real-time during brain mapping.

7.- Advanced intraoperative high gamma mapping can identify language areas like Wernicke's and Broca's areas without needing patient cooperation.

8.- "Asleep-awake-asleep" brain mapping was done using high gamma ECoG to preserve language function while maximally resecting a tumor.

9.- Repeated hand grasping tasks cause attenuation of high gamma activity over time in sensorimotor cortex, based on previous studies.

10.- Dr. Sanada's study tested high gamma attenuation in sensorimotor cortex during repeated grasping in 11 patients using subdural ECoG.

11.- 3D brain models were made by co-registering post-op MRI and CT to localize ECoG electrodes on the brain surface.

12.- Patients did 10 rounds of 10 hand grasping movements each while high gamma activity was recorded from sensorimotor electrodes.

13.- High gamma activity was compared between grasps and between rounds to quantify short-term and long-term attenuation.

14.- High gamma activity attenuated significantly from the 1st to 2nd and 2nd to 3rd grasps within rounds.

15.- High gamma activity also attenuated after the 1st round compared to later rounds, localizing most to the hand area.

16.- Single-trial analysis found high gamma peaked 700ms after movement onset and was higher for the 1st vs. 9th grasp.

17.- More sensorimotor electrodes showed long-term (50%) vs. short-term (25%) high gamma attenuation, especially near the anatomical hand knob.

18.- High gamma attenuation reduces the signal available for brain mapping, so paradigms should minimize grasps per round to maximize power.

19.- Prosopagnosia is impaired face recognition despite intact vision, associated with damage to the fusiform gyrus and inferior temporal gyrus.

20.- fMRI, ECoG, and ECS were compared for mapping face recognition areas in 5 epilepsy patients with implanted subdural electrodes.

21.- fMRI and ECoG detected more face-specific responses than ECS alone, but fMRI was affected by artifacts from skull base air spaces.

22.- ECoG had few artifacts and better detection than ECS, which only locally stimulated parts of the distributed face network.

23.- Combined fMRI and ECoG identified putative face areas ECS could not find that were safely resected without causing prosopagnosia.

24.- The CORTEQ 3D brain montage creator is a useful tool for making 3D electrode models for ECoG analysis.

25.- 3D brain montages can be made using pre-op MRI plus post-op CT, or using intra-op pictures when post-op CT is unavailable.

Knowledge Vault built byDavid Vivancos 2024