Abstract
Patients with bipolar disorder and schizophrenia often suffer from severe cognitive impairment even during times of remission. This study investigated the pathomechanisms underlying their deficits in cognitive control. A combined oddball–incongruence fMRI task was applied to examine similarities and differences of neural activation patterns between patients and healthy controls. Bipolar and schizophrenia patients demonstrated hyperactivations in the intraparietal cortex during the oddball condition. Furthermore, bipolar patients revealed diagnosis-specific hyperactivation in the left middle frontal gyrus, precentral gyrus, anteroventral prefrontal cortex and orbitofrontal cortex regions compared to schizophrenia patients and healthy individuals. In comparison to healthy controls the patients showed hypoactivations in the inferior frontal junction and ventral pathway during the cognitively more demanding incongruence. Taken together, bipolar patients seem to recruit frontal and parietal areas during the oddball condition to compensate for potential deficits in their attentional network. During more challenging tasks, i.e., the incongruence condition, their compensatory mechanisms seem to collapse leading to hypoactivations in the same frontal areas as well as the ventral pathway.
Highlights
Attention can be defined as the frail balance between concentration on task-relevant information and a continuous unconscious scanning of the environment for stimuli that demand behavioral responses
Follow-up analyses resulted in significant differences between schizophrenia patients and healthy controls (p = 0.001, r = − 0.422) as well as bipolar patients and healthy controls (p = 0.017, r = − 0.356), but not between the patient groups (p = 1.000, r = 0.047), indicating worse performance of both patient groups compared to healthy controls
Schizophrenia patients presented significantly worse performance compared to healthy controls (p = 0.002, r = − 0.408)
Summary
Attention can be defined as the frail balance between concentration on task-relevant information and a continuous unconscious scanning of the environment for stimuli that demand behavioral responses (background monitoring). Selective attention processes underlie cognitive control, which is the ability to focus on a specific stimulus while other stimuli might be present. A possible way to examine cognitive control is through stimulus–response compatibility tasks such as Stroop or incongruence tasks. Whereas the incongruence effect is elicited by response conflicts, oddball tasks have been related to a series of cognitive processes including categorization, response selection, execution of response, etc. Studies involving detection of unattended, but salient and behaviorally relevant stimuli indicate an impact of functional properties of frontoparietal regions (in particular the temporoparietal junction). Both tasks require a shielding of task-relevant processing from task-irrelevant stimulus information. Incongruence and oddball tasks share activation patterns in similar frontoparietal
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