Abstract
Sensory flooding, particularly during auditory stimulation, is a common problem for patients with schizophrenia. The functional consequences of this impairment during cross-modal attention tasks, however, are unclear. The purpose of this study was to examine how auditory distraction differentially affects task-associated response during visual attention in patients and healthy controls. To that end, 21 outpatients with schizophrenia and 23 healthy comparison subjects performed a visual attention task in the presence or absence of distracting, environmentally relevant “urban” noise while undergoing functional magnetic resonance imaging at 3T. The task had two conditions (difficult and easy); task-related neural activity was defined as difficult – easy. During task performance, a significant distraction (noise or silence) by group (patient or control) interaction was observed in the left dorsolateral prefrontal cortex, right hippocampus, left temporoparietal junction, and right fusiform gyrus, with patients showing relative hypoactivation during noise compared to controls. In patients, the ability to recruit the dorsolateral prefrontal cortex during the task in noise was negatively correlated with the effect of noise on reaction time. Clinically, the ability to recruit the fusiform gyrus during the task in noise was negatively correlated with SANS affective flattening score, and hippocampal recruitment during the task in noise was positively correlated with global functioning. In conclusion, schizophrenia may be associated with abnormalities in neural response during visual attention tasks in the presence of cross-modal noise distraction. These response differences may predict global functioning in the illness, and may serve as a biomarker for therapeutic development.
Highlights
Development of neuroimaging biomarkers for cognitive symptoms of schizophrenia, including deficits in sustained and selective attention, remains a priority for neuropsychiatric research
We have recently reported an inverse correlation between hippocampal activity during passive listening to urban noise and recruitment of the temporoparietal junction (TPJ) during an auditory tone discrimination task in patients, suggesting that hippocampal hyperactivity during noise may impair the ability of patients to engage task-relevant systems
A significant main effect of group was observed for errors of commission (F(3,36) = 17.3, p,0.001), and a trend towards a main effect of group was observed for errors of omission (F(3,36) = 2.95, p = 0.09)
Summary
Development of neuroimaging biomarkers for cognitive symptoms of schizophrenia, including deficits in sustained and selective attention, remains a priority for neuropsychiatric research. In early behavioral investigations of schizophrenia, patients often complained of being unable to ignore distracting sounds in the environment [1] This deficit has been hypothesized to reflect inhibitory dysfunction in brain areas important for sensory filtering, such as the hippocampus [2,3,4,5,6]. In support of this theory, patients show reduced gating of early (50 ms post-stimulus) event related potentials during repeated clicks [2], as well as increased hippocampal and dorsolateral prefrontal (DLPFC) response during passive listening to click trains [3] and environmental ‘‘urban noise’’ [4]. Hippocampal hyperactivity during low load may be a general mechanism by which, relative to controls, patients are less able to appropriately increase brain activity as task difficulty is increased, resulting in hypoactivation [15]
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