A hierarchy of event-related potential markers of auditory processing in disorders of consciousness.
Functional neuroimaging of covert perceptual and cognitive processes can inform the diagnoses and prognoses of patients with disorders of consciousness, such as the vegetative and minimally conscious states (VS;MCS). Here we report an event-related potential (ERP) paradigm for detecting a hierarchy of auditory processes in a group of healthy individuals and patients with disorders of consciousness. Simple cortical responses to sounds were observed in all 16 patients; 7/16 (44%) patients exhibited markers of the differential processing of speech and noise; and 1 patient produced evidence of the semantic processing of speech (i.e. the N400 effect). In several patients, the level of auditory processing that was evident from ERPs was higher than the abilities that were evident from behavioural assessment, indicating a greater sensitivity of ERPs in some cases. However, there were no differences in auditory processing between VS and MCS patient groups, indicating a lack of diagnostic specificity for this paradigm. Reliably detecting semantic processing by means of the N400 effect in passively listening single-subjects is a challenge. Multiple assessment methods are needed in order to fully characterise the abilities of patients with disorders of consciousness.
The Brain and Mind Institute, University of Western Ontario, London, ON, Canada; McGill Vision Research, Department of Ophthalmology, McGill University, Montreal, Canada.
Steve
S
Beukema
The Brain and Mind Institute, University of Western Ontario, London, ON, Canada.
Laura E
LE
Gonzalez-Lara
Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK.
Paola
P
Finoia
Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK.
Evelyn
E
Kamau
Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK.
Judith
J
Allanson
School of Computing, University of Kent, Chatham Maritime, UK; Department of Clinical Neurosciences, The University of Cambridge, Cambridge, UK.
Srivas
S
Chennu
The Brain and Mind Institute, University of Western Ontario, London, ON, Canada.
Raechelle M
RM
Gibson
Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK.
John D
JD
Pickard
The Brain and Mind Institute, University of Western Ontario, London, ON, Canada.
Adrian M
AM
Owen
School of Psychology, University of Birmingham, Birmingham, UK.
Damian
D
Cruse
D000161:Acoustic Stimulation; D000293:Adolescent; D000328:Adult; D000368:Aged; D001307:Auditory Perception / Q000502:physiology*; D015415:Biomarkers; D002540:Cerebral Cortex / Q000503:physiopathology*; D003244:Consciousness Disorders / Q000503:physiopathology*; D004569:Electroencephalography; D005072:Evoked Potentials, Auditory; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012660:Semantics; D013067:Speech Perception / Q000502:physiology; D055815:Young Adult
D015415:Biomarkers
Auditory processing; Disorders of consciousness; Minimally conscious state; N400; Vegetative state