Neural and behavioural investigation of auditory distraction in schizophrenia

This experiment was designed to assess whether a known abnormality in an index of sound relevance-filtering could be related to attention deficits reflecting problems in maintaining task focus in a clinical population. MMN elicited to rare unexpected changes in sound is considered part of a relevance-filtering process and reduced amplitude MMN is a robust finding in schizophrenia suggesting disrupted relevance filtering. This experimental paradigm enabled measurement of behavioural and neural correlates of task performance in order to compare a matched healthy control group to persons with a diagnosis of schizophrenia or related disorder (n =15). The paradigm included a passive auditory mismatch negativity (MMN) task (tone pitch manipulation) designed to elicit distraction (slower reaction times and less accurate responding) in a concurrent auditory target detection task (short or long tone).The schizophrenia group participants were recruited from a short-term mental health facility and were all medicated with anti-psychotic medication, with both groups completing neuropsychological testing and an EEG over multiple sessions. The expectation of reduced MMN amplitude in schizophrenia would be linked with less behavioural distraction was not met as the schizophrenia group exhibited increased behavioural distraction while producing equivalent size MMN responses to the control participants. This study, whilst acknowledging the limitations of the sample as well as potential methodological considerations, does not support evidence of a system less sensitive to distraction in schizophrenia. This is in keeping with the general observations of problems in sustained attention typically observed in participants with schizophrenia without a faulty relevance filter.