Article

Despite recent evidence suggesting that some severely brain-injured
patients retain some capacity for top-down processing (covert cognition), the
degree of sparing is unknown. OBJECTIVE: Top-down attentional processing was
assessed in patients in minimally conscious (MCS) and vegetative states (VS)
using an active event-related potential (ERP) paradigm. METHODS: A total of 26
patients were included (38 +/- 12 years old, 9 traumatic, 21 patients >1 year
postonset) : 8 MCS+, 8 MCS-, and 10 VS patients. There were 14 healthy controls
(30 +/- 8 years old). The ERP paradigm included (1) a passive condition and (2)
an active condition, wherein the participant was instructed to voluntarily focus
attention on his/her own name. In each condition, the participant's own name was
presented 100 times (ie, 4 blocks of 25 stimuli). RESULTS: In 5 MCS+ patients as
well as in 3 MCS- patients and 1 VS patient, an enhanced P3 amplitude was
observed in the active versus passive condition. Relative to controls, patients
showed a response that was (1) widely distributed over frontoparietal areas and
(2) not present in all blocks (3 of 4). In patients with covert cognition, the
amplitude of the response was lower in frontocentral electrodes compared with
controls but did not differ from that in the MCS+ group. CONCLUSION: The results
indicate that volitional top-down attention is impaired in patients with covert
cognition. Further investigation is crucially needed to better understand
top-down cognitive functioning in this population because this may help refine
brain-computer interface-based communication strategies.
CI - (c) The Author(s) 2014.

Langue : ANGLAIS