Knowledge Vault 3/99 - G.TEC BCI & Neurotechnology Spring School 2024 - Day 10
Dynamic tractography atlas animates the physiologic and
pathologic network dynamics through the white matter
Eishi Asano, Wayne State University (USA)
<Resume Image >

Concept Graph & Resume using Claude 3 Opus | Chat GPT4 | Llama 3:

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imaging biomarker. 1] A --> C[Integrates neuroimaging, neurophysiology
to animate propagation. 2] C --> D[Velocity estimated using MRI
location/length, EEG latency. 3] C --> E[CCEP, CCSR evaluate propagation latency. 4] B --> F[2018 prototype simulated propagation's
size, intensity, speed, direction. 5] F --> G[Visualized intra/interhemispheric propagation,
validated with CCSR. 6] A --> H[2021 study assessed language
using '6D' dynamic tractography. 7] H --> I[Distinct spatiotemporal high gamma
patterns during naming task. 8] H --> J[Propagation primarily through arcuate,
some uncinate fasciculus. 9] J --> K[Tracts connected frontal, temporal
sites during response preparation. 10] H --> L[Investigating if improves language
mapping, deficit prediction. 11] L --> M[High gamma responses predicted
post-op language scores. 12] L --> N[Machine learning with responses
predicted deficits, tractography may improve. 13] A --> O[Studying brain requires assessing
connectivity, dynamics, information content. 14] O --> P[Dynamic tractography suited for
connectivity, dynamics assessment. 15] A --> Q[Videos demonstrated connectivity
modulation during naming tasks. 16] Q --> R[Interhemispheric occipital enhancements
may support image integration. 17] Q --> S[Posterior-anterior propagation observed
during response preparation. 18] A --> T[Could refine language models
with temporal, pathway information. 19] A --> U[Used to localize, animate
interictal spike propagation. 20] U --> V[Entropy quantified spike source
aggregation for propagation models. 21] U --> W[Seizure-free temporal lobe patients
had localized spike propagation. 22] U --> X[Non-seizure-free had extensive
propagation beyond temporal lobe. 23] U --> Y[Spike confinement to resected
region may predict outcomes. 24] A --> Z[Limitations exist due to
DTI false negatives. 25] A --> AA[Future aims: clarify thalamocortical
dynamics, assess clinical utility. 26] A --> AB[Memory networks mapped, showing
load-dependent activity increases. 27] AB --> AC[Occipital-temporal connectivity increased
with load, other regions deactivated. 28] AB --> AD[High gamma, connectivity reductions
observed with task familiarity. 29] A --> AE[Potential applications in TBI,
psychiatric disorders. 30] class A,B,F,Z imaging; class C,D,E,O,P neuroimaging; class G,Q,R,S,U,V,W,X,Y propagation; class H,I,J,K,L,M,N,T language; class AA,AE future; class AB,AC,AD memory; class W,X,Y,Z epilepsy;


1.- Dynamic tractography is a promising intracranial EEG-based imaging biomarker for epilepsy pre-surgical evaluations and understanding white matter's role in cognitive function.

2.- It integrates neuroimaging and neurophysiology to animate rapid neural propagation or modulation in functional connectivity through MRI-defined 3D white matter tracts.

3.- Propagation velocity is estimated using MRI tractography to determine white matter streamline location/length and intracranial EEG to measure propagation latency.

4.- Cortical-cortical evoked potentials (CCEP) and cortical-cortical spectral responses (CCSR) are used to evaluate propagation latency after single-pulse electrical stimulation.

5.- The first dynamic tractography prototype in 2018 simulated evaluating size, intensity, speed and direction of neural propagation through white matter.

6.- Early work visualized intrahemispheric and interhemispheric neural propagation, with validation using CCSR latency at adjacent areas and Japanese research.

7.- A 2021 study assessed the human language system using "6D" dynamic tractography incorporating MRI, EEG timing, connectivity strength and velocity measures.

8.- Group data showed distinct spatiotemporal high gamma activity patterns in bilateral cortical areas during different stages of an auditory naming task.

9.- Dynamic tractography revealed neural propagation related to language primarily through the arcuate fasciculus, with some involvement of the uncinate fasciculus.

10.- Red-colored white matter tracts connected frontal and temporal sites exhibiting simultaneous high gamma activity during response preparation in the naming task.

11.- Whether dynamic tractography improves language mapping or predicting region-specific language deficits after surgery is currently being investigated.

12.- Naming-related high gamma responses were found to predict post-operative core language scores, suggesting removing those sites risks cognitive deficits.

13.- A machine learning model with spectral responses predicted language deficits with 0.80 accuracy; dynamic tractography measures may further improve this.

14.- Studying the complex brain comprehensively requires evaluating connectivity, temporal dynamics and underlying information content (pathological vs physiological).

15.- Dynamic tractography is well-suited for assessing white matter connectivity and neural dynamics, while other approaches are needed for information content.

16.- Videos demonstrated dynamic tractography of functional connectivity modulation during picture naming and auditory naming tasks.

17.- Interhemispheric occipital connectivity enhancements may support integration of visual image representations processed in each hemisphere.

18.- Posterior-to-anterior propagation of connectivity enhancements was observed during response preparation, with motor and auditory connectivity increases during responses.

19.- Dynamic tractography could refine language models by providing temporal dynamics and pathway-specific information compared to static depictions.

20.- It was also used to localize and animate the propagation of interictal spike discharges in epilepsy patients.

21.- Candidate spike source aggregation was quantified using entropy to determine the most plausible propagation model for a given spike.

22.- Seizure-free post-surgery medial temporal lobe epilepsy patients showed spike propagation mostly confined to that region in group data.

23.- Regional temporal lobe epilepsy patients had more extensive spike propagation beyond the temporal lobe, even in seizure-free surgical cases.

24.- Preliminary data suggests estimated spike source confinement to the resected region may predict positive seizure surgery outcomes.

25.- Limitations exist due to DTI tractography's propensity for false negatives, requiring cautious interpretation of absent tracts.

26.- Future work aims to clarify thalamocortical propagation dynamics and assess dynamic tractography's clinical utility.

27.- Memory networks were also mapped, showing memory load-dependent high gamma activity increases in occipital and medial temporal regions.

28.- Functional connectivity between occipital and medial temporal areas increased with memory load, while other regions exhibited relative deactivations.

29.- High gamma and connectivity reductions were observed with task familiarity, except in portions of the inferior frontal gyrus.

30.- Dynamic tractography has potential applications in traumatic brain injury and psychiatric disorders. Connectivity strength can be estimated from simultaneous regional activations.

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