Neurophysiological Indicators of Residual Cognitive Capacity in the Minimally Conscious State.
BACKGROUND
The diagnostic usefulness of electrophysiological methods in assessing disorders of consciousness (DoC) remains to be established on an individual patient level, and there is need to determine what constitutes robust experimental paradigm to elicit electrophysiological indices of covert cognitive capacity.


OBJECTIVE
Two tasks encompassing active and passive conditions were explored in an event-related potentials (ERP) study. The task robustness was studied in healthy controls, and their utility to detect covert signs of command-following on an individual patient level was investigated in patients in a minimally conscious state (MCS).


METHODS
Twenty healthy controls and 20 MCS patients participated. The active tasks included (1) listening for a change of pitch in the subject's own name (SON) and (2) counting SON, both contrasted to passive conditions. Midline ERPs are reported.


RESULTS
A larger P3 response was detected in the counting task compared to active listening to pitch change in the healthy controls. On an individual level, the counting task revealed a higher rate of responders among both healthy subjects and MCS patients.


CONCLUSIONS
ERP paradigms involving actively counting SON represent a robust paradigm in probing for volitional cognition in minimally conscious patients and add important diagnostic information in some patients.
Department of Research, Sunnaas Rehabilitation Hospital, 1450 Nesoddtangen, Norway.
Solveig L
SL
Hauger
Department of Psychology and Neurosurgery, University of California, Los Angeles, CA 90095-1563, USA.
Caroline
C
Schnakers
Department of Psychology, University of Oslo, Postboks 1094 Blindern, 0317 Oslo, Norway.
Stein
S
Andersson
Department of Research, Sunnaas Rehabilitation Hospital, 1450 Nesoddtangen, Norway ; Institute of Clinical Medicine, University of Oslo, Postboks 1171 Blindern, 0318 Oslo, Norway.
Frank
F
Becker
Norwegian Centre for Mental Disorders Research (NORMENT), KG Jebsen Centre for Psychosis Research, Division of Mental Health and Addiction, Oslo University Hospital, Postboks 4953 Nydalen, 0424 Oslo, Norway ; Regional Center of Knowledge Translation in Rehabilitation, Sunnaas Rehabilitation Hospital, 1450 Nesoddtangen, Norway.
Torgeir
T
Moberget
Department of Physical Medicine and Rehabilitation, Harvard Medical School and Spaulding Rehabilitation Hospital, 300 First Avenue, Charlestown, MA 02129, USA.
Joseph T
JT
Giacino
Department of Research, Sunnaas Rehabilitation Hospital, 1450 Nesoddtangen, Norway ; Department of Psychology, University of Oslo, Postboks 1094 Blindern, 0317 Oslo, Norway.
Anne-Kristine
AK
Schanke
Department of Research, Sunnaas Rehabilitation Hospital, 1450 Nesoddtangen, Norway ; Department of Psychology, University of Oslo, Postboks 1094 Blindern, 0317 Oslo, Norway.
Marianne
M
Løvstad
D000161:Acoustic Stimulation; D000293:Adolescent; D000328:Adult; D000368:Aged; D001307:Auditory Perception / Q000502:physiology; D001921:Brain / Q000503:physiopathology*; D003071:Cognition / Q000502:physiology*; D003243:Consciousness / Q000502:physiology*; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology*; D005072:Evoked Potentials, Auditory / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018458:Persistent Vegetative State / Q000503:physiopathology*; D055815:Young Adult