Knowledge Vault 3/86 - G.TEC BCI & Neurotechnology Spring School 2024 - Day 9
Functional neurodiagnostics for patients with Disorders of Consciousness
Damian Cruse, University of Birmingham (UK)
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Concept Graph & Resume using Claude 3 Opus | Chat GPT4 | Llama 3:

graph LR classDef cruse fill:#f9d4d4, font-weight:bold, font-size:14px; classDef brain fill:#d4f9d4, font-weight:bold, font-size:14px; classDef patients fill:#d4d4f9, font-weight:bold, font-size:14px; classDef eeg fill:#f9f9d4, font-weight:bold, font-size:14px; classDef speech fill:#f9d4f9, font-weight:bold, font-size:14px; A[Damian Cruse] --> B[fMRI, EEG, BCI experiments. 1] A --> C[Zebrafish brain video shows
brain complexity. 2] C --> D[Impossible to read minds
from outside. 3] A --> E[Brain injury can cause
vegetative state. 4] E --> F[Determining consciousness has
profound implications. 5] A --> G[EEG may detect consciousness
in unresponsive patients. 6] G --> H[Mu rhythm suppressed during
movement, imagery. 7] H --> I[Motor imagery proxy for
awareness, consciousness. 8] I --> J[Vegetative patients with normal
imagery EEG misdiagnosed. 9] I --> K[Motor imagery challenging,
low sensitivity. 10] G --> L[Resting EEG reflects brain
health, not consciousness. 11] A --> M[Speech elicits perceptual, cognitive
processes, conscious experiences. 12] M --> N[N400 ERP indexes semantic
processing, even unconsciously. 13] M --> O[Hierarchical approach: sound, speech,
semantic responses. 14] O --> P[High-level processing occurs in
sleep, N400 alone insufficient. 15] M --> Q[Brain tracks linguistic structures,
reflects comprehension. 16] Q --> R[Tracking breaks down when
unconscious, language unknown. 17] Q --> S[Classifiers differentiate conscious vs
unconscious above chance. 18] Q --> T[Acute sentence response predicts
6-month recovery. 19] Q --> U[Sentence tracking in unresponsive
suggests consciousness. 20] A --> V[BCI communication challenging, but
improves EEG diagnosis. 21] M --> W[N400 less reliable with
passive single-subject detection. 22] M --> X[Aphasia could cause false
negatives on tests. 23] Q --> Y[Inter-trial phase coherence stronger
than power for tracking. 24] M --> Z[Meaningful stimuli may elicit
stronger EEG markers. 25] I --> AA[Mu rhythm detects covert
command-following in misdiagnosed. 26] AA --> AB[Command-following patients have
better long-term outcomes. 27] G --> AC[Asking too much of
DOC patients problematic. 28] M --> AD[Measuring natural speech responses
may infer consciousness. 29] G --> AE[EEG language markers could
aid DOC diagnosis, prognosis. 30] class A,B cruse; class C,D brain; class E,F,AA,AB,AC,AE patients; class G,H,I,J,K,L,S,T,U,V,Y eeg; class M,N,O,P,Q,R,W,X,Z,AD speech;


1.- Damian Cruse returned to Birmingham 9 years ago and is doing experiments with fMRI, EEG and BCI technology.

2.- A video of a larval zebrafish brain shows the complexity of the brain, with humans having 800,000 times more neurons.

3.- It is intractable to truly read someone's mind from the outside due to the brain's enormous complexity.

4.- Patients with severe brain injuries can end up in a vegetative state, appearing wakeful but showing no signs of consciousness.

5.- Determining if an unresponsive patient is conscious has profound implications, as it affects diagnosis, prognosis and life-sustaining therapy decisions.

6.- EEG can potentially help determine if an unresponsive patient is conscious by detecting specific brain activity patterns.

7.- The mu rhythm, an EEG oscillation over sensorimotor regions, is suppressed both when moving and imagining movement.

8.- Mental imagery of movement can be used as a proxy for whether an unresponsive patient is following instructions and conscious.

9.- Some apparently vegetative patients produce normal EEG responses to motor imagery, suggesting they are covertly aware and misdiagnosed.

10.- Motor imagery paradigms are cognitively demanding for many patients and have low sensitivity for detecting consciousness.

11.- Resting state EEG measures like alpha power correlate with prognosis but may reflect brain health more than consciousness per se.

12.- Speech is a powerful stimulus, eliciting a cascade of perceptual and cognitive processes that can induce subjective conscious experiences.

13.- The N400 ERP indexes semantic processing of speech, but can occur in some unconscious states like sleep.

14.- A hierarchical approach looks at cortical responses to sound, speech-specific responses, and semantic context effects in patients.

15.- High-level semantic processing like word categorization can occur during sleep, so N400 effects alone don't prove consciousness.

16.- The brain tracks the rate of phrases and sentences in speech stimuli lacking acoustic cues, reflecting conscious comprehension.

17.- This tracking of linguistic structures breaks down in sleep and when the language is not understood, linking it to consciousness.

18.- Classifiers using sentence-rate tracking can differentiate conscious from unconscious patients above chance, but categories are behaviorally confounded.

19.- The magnitude of a patient's sentence-level response in the acute phase predicts their degree of functional recovery 6 months later.

20.- If an unresponsive patient shows the sentence-tracking response that only occurs in conscious people who understand, they are likely conscious.

21.- BCI communication will likely remain very challenging for DOC patients, but BCI advances can improve diagnostic/prognostic EEG measures.

22.- The N400 ERP is less reliable for single-subject detection with passive listening compared to active, engaging tasks.

23.- Language comprehension impairments in aphasia could cause false negatives on behavioral and EEG-based consciousness tests.

24.- Inter-trial phase coherence of the EEG at the sentence rate is a stronger measure than power for detecting language tracking.

25.- Using personally meaningful, engaging stimuli like a story told by the patient's mother may help elicit stronger EEG markers.

26.- The mu rhythm response allows detecting covert command-following in unresponsive patients who are likely conscious but misdiagnosed.

27.- Cognitive-motor dissociation patients who show EEG command-following tend to have better long-term outcomes than those who don't.

28.- Directly asking too much of DOC patients with BCI is problematic due to cognitive impairment and lack of training.

29.- Measuring the brain's natural responses to speech may be a more feasible way to infer the presence of consciousness.

30.- With further validation, EEG markers of language processing could become valuable clinical tools for diagnosis and prognosis in DOC.

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