Editors' ChoiceTraumatic Brain Injury

Imaging covert consciousness

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Science Translational Medicine  09 Aug 2017:
Vol. 9, Issue 402, eaao2260
DOI: 10.1126/scitranslmed.aao2260

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  • RE: Imaging covert consciousness
    • Brian L Edlow, Neurologist, Massachusetts General Hospital
    • Other Contributors:
      • Camille Chatelle, Investigator, Coma Science Group

    We thank Dr. Choi (1) for his thoughtful discussion of the key findings and limitations of our study, “Early detection of consciousness in patients with acute severe traumatic brain injury” (2). We also wish to clarify our a priori criteria for covert consciousness in patients with severe brain injuries who appeared unconscious on bedside behavioral examination. Specifically, functional MRI or EEG evidence of command-following during a motor imagery task was considered to be sufficient evidence for covert consciousness, consistent with criteria recently proposed by Schiff (3). In contrast, functional MRI and EEG evidence of a brain response to spoken language or music was not considered sufficient proof of covert consciousness, even if the response occurred within higher-order association cortex. Rather, prior functional MRI studies of healthy human subjects have shown that association cortices may respond to spoken language even when a subject is sedated and minimally responsive on behavioral examination (4). Until future studies elucidate the relationship between association cortex responses and consciousness, we caution against the interpretation that association cortex responses are evidence of covert consciousness in patients with severe brain injuries.

    1. H. A. Choi, Imaging covert consciousness. Science translational medicine 9, eaao2260 (2017).
    2. B. L. Edlow et al., Early detection of consciousness in patients with acute severe traumatic brain...

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    Competing Interests: None declared.