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Dissociable endogenous and exogenous attention in disorders of consciousness

Chennu, Srivas, Finoia, Paola, Kamau, Evelyn, Monti, Martin M., Allanson, Judith, Pickard, John D., Owen, Adrian M., Bekinschtein, Tristan A. (2013) Dissociable endogenous and exogenous attention in disorders of consciousness. NeuroImage: Clinical, 3 . pp. 450-461. E-ISSN 2213-1582. (doi:10.1016/j.nicl.2013.10.008) (KAR id:54639)


Recent research suggests that despite the seeming inability of patients in vegetative and minimally conscious states to generate consistent behaviour, some might possess covert awareness detectable with functional neuroimaging. These findings motivate further research into the cognitive mechanisms that might support the existence of consciousness in these states of profound neurological dysfunction. One of the key questions in this regard relates to the nature and capabilities of attention in patients, known to be related to but distinct from consciousness. Previous assays of the electroencephalographic P300 marker of attention have demonstrated its presence and potential clinical value. Here we analysed data from 21 patients and 8 healthy volunteers collected during an experimental task designed to engender exogenous or endogenous attention, indexed by the P3a and P3b components, respectively, in response to a pair of word stimuli presented amongst distractors. Remarkably, we found that the early, bottom-up P3a and the late, top-down P3b could in fact be dissociated in a patient who fitted the behavioural criteria for the vegetative state. In juxtaposition with healthy volunteers, the patient's responses suggested the presence of a relatively high level of attentional abilities despite the absence of any behavioural indications thereof. Furthermore, we found independent evidence of covert command following in the patient, as measured by functional neuroimaging during tennis imagery. Three other minimally conscious patients evidenced non-discriminatory bottom-up orienting, but no top-down engagement of selective attentional control. Our findings present a persuasive case for dissociable attentional processing in behaviourally unresponsive patients, adding to our understanding of the possible levels and applications of consequent conscious awareness.

Item Type: Article
DOI/Identification number: 10.1016/j.nicl.2013.10.008
Uncontrolled keywords: Vegetative state; Minimally conscious state; Attention; Consciousness; Electroencephalography
Subjects: B Philosophy. Psychology. Religion > BF Psychology
Divisions: Faculties > Sciences > School of Computing
Depositing User: Srivas Chennu
Date Deposited: 13 Apr 2016 09:25 UTC
Last Modified: 24 Jan 2020 04:08 UTC
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Chennu, Srivas:
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