title: Finding the missing-stimulus mismatch negativity (MMN) in early psychosis: altered MMN to violations of an auditory gestalt.
abstract: The mismatch negativity (MMN) is an EEG-derived event-related potential (ERP) elicited by any violation of a predicted auditory 'rule', regardless of whether one is attending to the stimuli, and is thought to reflect updating of the stimulus context. Chronic schizophrenia patients exhibit robust MMN deficits, while MMN reduction in first-episode and early phase psychosis is significantly less consistent. Traditional two-tone "oddball" MMN measures of sensory information processing may be considered too simple for use in early phase psychosis in which pathology has not progressed fully, and a paradigm that probes higher order processes may be more appropriate for elucidating auditory change detection deficits. This study investigated whether MMN deficits could be detected in early phase psychosis (EP) patients using an abstract 'missing stimulus' pattern paradigm (Salisbury, 2012). The stimuli were 400 groups of six tones (1000Hz, 50ms duration, 330ms stimulus onset asynchrony), which was presented with an inter-trial interval of 750ms. Occasionally a group contained a deviant, meaning that it was missing either the 4th or 6th tone (50 trials each). EEG recordings of 13 EP patients (≤5year duration of illness) and 15 healthy controls (HC) were collected. Patients and controls did not significantly differ on age or years of education. Analyses of MMN amplitudes elicited by missing stimuli revealed amplitude reductions in EP patients, suggesting that these deficits are present very early in the progression of the illness. While there were no correlations between MMN measures and measures such as duration of illness, medication dosage or age, MMN amplitude reductions were correlated with positive symptomatology (i.e. auditory hallucinations). These findings suggest that MMNs elicited by the 'missing stimulus' paradigm are impaired in psychosis patients early in the progression of illness and that previously reported MMN-indexed deficits related to auditory hallucinations in chronic patients may also be present in EP patients. As such, this paradigm may have promise in identifying early processing deficits in this population.
authors.affiliation: Department of Psychology, Mount Saint Vincent University, Halifax, Nova Scotia, Canada.
authors.forename: Erica D
authors.initials: ED
authors.lastname: Rudolph
authors.affiliation: Department of Psychology, Mount Saint Vincent University, Halifax, Nova Scotia, Canada.
authors.forename: Emma M L
authors.initials: EM
authors.lastname: Ells
authors.affiliation: Department of Psychology, Mount Saint Vincent University, Halifax, Nova Scotia, Canada.
authors.forename: Debra J
authors.initials: DJ
authors.lastname: Campbell
authors.affiliation: Department of Psychology, Mount Saint Vincent University, Halifax, Nova Scotia, Canada.
authors.forename: Shelagh C
authors.initials: SC
authors.lastname: Abriel
authors.affiliation: Department of Psychiatry, Dalhousie University, Halifax, Nova Scotia, Canada; Capital District Health Authority, Halifax, Nova Scotia, Canada.
authors.forename: Philip G
authors.initials: PG
authors.lastname: Tibbo
authors.affiliation: Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
authors.forename: Dean F
authors.initials: DF
authors.lastname: Salisbury
authors.affiliation: Department of Psychology, Mount Saint Vincent University, Halifax, Nova Scotia, Canada; Department of Psychiatry, Dalhousie University, Halifax, Nova Scotia, Canada; Capital District Health Authority, Halifax, Nova Scotia, Canada. Electronic address: derek.fisher@msvu.ca.
authors.forename: Derek J
authors.initials: DJ
authors.lastname: Fisher
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D001307:Auditory Perception / Q000502:physiology*; D001921:Brain / Q000503:physiopathology*; D004569:Electroencephalography; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D011618:Psychotic Disorders / Q000503:physiopathology*; D055815:Young Adult
keywords: Auditory event-related potentials; Auditory hallucinations; Early psychosis; MMN; Mismatch negativity; Schizophrenia