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Deficits in mismatch negativity (MMN) generation are among the best-established biomarkers for cognitive dysfunction in schizophrenia and predict conversion to schizophrenia (Sz) among individuals at symptomatic clinical high risk (CHR). Impairments in MMN index dysfunction at both subcortical and cortical components of the early auditory system. To date, the large majority of studies have been conducted using deviants that differ from preceding standards in either tonal frequency (pitch) or duration. By contrast, MMN to sound location deviation has been studied to only a limited degree in Sz and has not previously been examined in CHR populations. Here, we evaluated location MMN across Sz and CHR using an optimized, multi-deviant pattern that included a location-deviant, as defined using interaural time delay (ITD) stimuli along with pitch, duration, frequency modulation (FM) and intensity deviants in a sample of 42 Sz, 33 CHR and 28 healthy control (HC) subjects. In addition, we obtained resting state functional connectivity (rsfMRI) on CHR subjects. Sz showed impaired MMN performance across all deviant types, along with strong correlation between MMN deficits and impaired neurocognitive function. In this sample of largely non-converting CHR subjects, no deficits were observed in either pitch or duration MMN. By contrast, CHR subjects showed significant impairments in location MMN generation particularly over right hemisphere and significant correlation between impaired location MMN and negative symptoms including deterioration of role function. In addition, significant correlations were observed between location MMN and rsfMRI involving brainstem circuits. In general, location detection using ITD stimuli depends upon precise processing within midbrain regions and provides a rapid and robust reorientation of attention. Present findings reinforce the utility of MMN as a pre-attentive index of auditory cognitive dysfunction in Sz and suggest that location MMN may index brain circuits distinct from those indexed by other deviant types.

Deficits in mismatch negativity (MMN) generation are among the best-established biomarkers for cognitive dysfunction in schizophrenia and predict conversion to schizophrenia (Sz) among individuals at symptomatic clinical high risk (CHR). Impairments in MMN index dysfunction at both subcortical and cortical components of the early auditory system. To date, the large majority of studies have been conducted using deviants that differ from preceding standards in either tonal frequency (pitch) or duration. By contrast, MMN to sound location deviation has been studied to only a limited degree in Sz and has not previously been examined in CHR populations. Here, we evaluated location MMN across Sz and CHR using an optimized, multi-deviant pattern that included a location-deviant, as defined using interaural time delay (ITD) stimuli along with pitch, duration, frequency modulation (FM) and intensity deviants in a sample of 42 Sz, 33 CHR and 28 healthy control (HC) subjects. In addition, we obtained resting state functional connectivity (rsfMRI) on CHR subjects. Sz showed impaired MMN performance across all deviant types, along with strong correlation between MMN deficits and impaired neurocognitive function. In this sample of largely non-converting CHR subjects, no deficits were observed in either pitch or duration MMN. By contrast, CHR subjects showed significant impairments in location MMN generation particularly over right hemisphere and significant correlation between impaired location MMN and negative symptoms including deterioration of role function. In addition, significant correlations were observed between location MMN and rsfMRI involving brainstem circuits. In general, location detection using ITD stimuli depends upon precise processing within midbrain regions and provides a rapid and robust reorientation of attention. Present findings reinforce the utility of MMN as a pre-attentive index of auditory cognitive dysfunction in Sz and suggest that location MMN may index brain circuits distinct from those indexed by other deviant types. [ABSTRACT FROM AUTHOR]

Auditory distractibility was investigated using four noise stimuli that differed in their duration and/or sound source. In the duration-task/location-deviant condition, participants were asked to discriminate between equiprobable short and long stimuli. Mostly, stimuli were presented from one location (Standards), but, infrequently, a stimulus was presented from another location (Deviant). In the location-task/duration-deviant condition, participants had to discriminate between stimuli presented equiprobably from the speaker in front of them or to their left. Here, most stimuli were of equal duration (Standards), but, infrequently, a stimulus duration changed (Deviant). The rare deviations in location and duration were irrelevant for the actual task. Whether they affected processes related to the actual task was assessed with performance- and event-related potential (ERP) measures. In both conditions, responses to Deviants were slowed compared to responses to Standards. Deviants elicited ERP components mismatch negativity (MMN), P3a and reorienting negativity (RON). These results show that the processing of both a sound’s duration and a sound’s location can be distracted by rare, but irrelevant, changes in its location and duration, respectively. Behavioral distraction effects were markedly smaller with duration Deviants. It is suggested that duration Deviants interfere with task-related processing at later stages than location Deviants, as the processing of task-relevant information (i.e. stimulus location) commences before deviation in the location-task/duration-deviant condition occurs. Interestingly, distraction effects also prevail in the first Standard stimulus after a Deviant, as indicated by the prolonged response times and late negativity in the ERPs. [Copyright &y& Elsevier]