Search

Spite sensitivity provides a valuable construct to understand persecutory ideation and its underlying neural mechanisms. We examined the relationship between persecution and spite sensitivity in psychosis to identify their neural substrates.

Objective: People with schizophrenia have exhibited reduced functional activity in the anterior cingulate cortex during the performance of many types of cognitive tasks and during the commission of errors. According to conflict theory, the anterior cingulate cortex is involved in the monitoring of response conflict, acting as a signal for a need for greater cognitive control. This study examined whether impaired conflict monitoring in people with schizophrenia could underlie reduced anterior cingulate activity during both correct task performance and error-related activity. Method: Functional activity in the anterior cingulate of 13 schizophrenia patients and 13 healthy comparison subjects was investigated by using event-related fMRI and a Stroop task that allowed simultaneous examination of activity during both conflict (incongruent trials) and error (commission of error trials). Results: In the presence of comparable reaction time measures for conflict as well as comparable error rates, the schizophrenia subjects showed both decreased conflict-and error-related activity in the same region of the anterior cingulate cortex. Moreover, those with schizophrenia did not exhibit significant post-conflict or post-error behavioral adjustments. Conclusions: Concurrently reduced conflict-and error-related activity in the anterior cingulate cortex along with reduced trial-to-trial adjustments in performance has not previously been reported in schizophrenia. The current results suggest that impaired conflict monitoring by the anterior cingulate cortex might play an important role in contributing to cognitive control deficits in patients with schizophrenia.

Objective: Context processing is a cognitive construct associated with activity in the middle frontal gyrus. Schizophrenia-related deficits in context processing tasks have been associated with prefrontal cortical dysfunction. This study evaluated whether prefrontal cortical dysfunction related to context processing occurred in first-episode, never-medicated schizophrenia patients, whether this dysfunction also occurred in patients with nonschizophrenia psychosis, and whether this dysfunction was related to psychotic symptom expression. Method: A modified version of the AX continuous performance task was conducted during event-related functional magnetic resonance imaging in 18 never-medicated, first-episode schizophrenia patients, 12 never-medicated patients with first-episode nonschizophrenia psychosis, and 28 comparison participants without psychiatric disorder. Results: In-scanner measures of errors and interference reaction time showed that the schizophrenia patients had a specific deficit in context processing. Trials with greater context processing demands corresponded to activity in the middle frontal gyrus (Brodmann's area 9) in the comparison subjects and in the patients with nonschizophrenia psychosis, but not in the schizophrenia patients. Individual differences in prefrontal cortical dysfunction were associated with context processing measures and disorganization symptoms. The schizophrenia patients also showed increased activity in the anterior (Brodmann's area 10) and inferior prefrontal cortices (Brodmann's area 45/46) when they were maintaining context over a delay. Conclusions: Prefrontal dysfunctions related to context processing were found only in schizophrenia patients early in the course of the illness, and these dysfunctions were related to disorganization symptoms. Instead of using context processing during a continuous performance task, schizophrenia patients may use an inefficient encoding and retrieval strategy.

Objective: The authors examined brain activity associated with the internal monitoring of performance to test the hypothesis that error-related activity in the anterior cingulate cortex is impaired in patients with schizophrenia. Method: Seventeen patients with schizophrenia and 16 healthy comparison subjects underwent event-related functional magnetic resonance imaging during a continuous performance task; stimulus degradation was used to increase error rates. Results: Comparison subjects, but not schizophrenic patients, showed error-related activity in the anterior cingulate cortex, and this difference in brain activity was significantly different across the two groups. Patients also showed less slowing of reaction time after error commission. Conclusions: Lower error-related activity in the anterior cingulate cortex and less performance adjustment after error commission are consistent with the hypothesis that disturbances in anterior cingulate cortex function are related to a specific alteration in an evaluative component of executive functioning--the internal monitoring of performance. (Am J Psychiatry 2001; 158:1423-1428)

People with psychosis and mood disorders experience disruptions in working memory; however, the underlying mechanism remains unknown. We focused on 2 potential mechanisms: first, poor attentional engagement should be associated with elevated levels of prestimulus alpha-band activity within the electroencephalogram (EEG), whereas impaired working memory encoding should be associated with reduced poststimulus alpha suppression.

People with schizophrenia (PSZ) have profound deficits in context processing, an executive process that guides adaptive behaviors according to goals and stored contextual information. Although various neural processes are involved in context processing and are affected in PSZ, the core underlying neural dysfunction is unclear.

Thalamic projections to the prefrontal cortex (PFC) are critical for cognition, and disruptions in these circuits are thought to underlie the pathophysiology of schizophrenia. Cognitive remediation training (REM) is a behavioral intervention that holds promise for improving cognition and functioning in schizophrenia; however, the extent to which it affects thalamo-prefrontal connections has not been researched. This study sought to determine whether patients with schizophrenia who undergo a placebo-controlled trial of REM show increased functional connectivity between the thalamus and PFC, and whether these changes correspond to improvements in cognition.

Psychotic-like experiences (PLEs) are considered the subclinical portion of the psychosis continuum. Research suggests that there are resting-state functional connectivity (rsFC) substrates of PLEs, yet it is unclear if the same substrates underlie more severe psychosis. Here, to our knowledge, we report the first study to build a cross-validated rsFC model of PLEs in a large community sample and directly test its ability to explain psychosis in an independent sample of patients with psychosis and their relatives.

Background:As resting-state functional connectivity (rsFC) research moves toward the study of individual differences, test–retest reliability is increasingly important to understand. Previous literature supports the test–retest reliability of rsFC derived with independent component analysis (ICA) and dual regression, yet the impact of dimensionality (i.e., the number of components to extract from group-ICA) remained obscure in the current context of large-scale data sets.Methods: To provide principled guidelines on this issue, ICA at dimensionalities varying from 25 to 350 was applied to the cortical surface with resting-state functional magnetic resonance imaging data from 1003 participants in the Human Connectome Project. The reliability of two rsFC measures, (within-component) coherence and (between-component) connectivity, was estimated.Results:Reliability and its change with dimensionality varied by network: the cognitive (frontoparietal, cingulo-opercular, dorsal attention, and default) networks were measured with the highest reliability, which improved with increased dimensionality until at least 150; the visual and somatomotor networks were measured with lower reliability, which benefited mildly from increased dimensionality; and the temporal pole/orbitofrontal cortex (TP/OFC) network was measured with the lowest reliability. Overall, ICA reliability was optimized at dimensionalities of 150 or above. Compared with two popular binary, nonoverlapping cortical atlases, ICA and dual regression resulted in higher reliability for the cognitive networks, lower reliability for the somatomotor network, and similar reliability for the visual and TP/OFC networks.Discussion:These findings highlight analytical decisions that maximize the reliability of rsFC measures and how they depend on one's networks of interest.Impact statementIndependent component analysis (ICA) and dual regression is a popular approach to resting-state functional connectivity (rsFC) analysis. Yet there is little consensus around the optimal ICA dimensionality, i.e., how many brain components to extract from group-ICA. We proposed that rsFC test-retest reliability is an important criterion when choosing dimensionality. The present study compares rsFC reliability across various dimensionalities in the state-of-the-art Human Connectome Project data. We also compared reliability based on ICA versus two popular brain atlases. The findings are of interest to both researchers who study brain parcellation and those who use rsFC to examine brain-behavior relationship.

Psychiatric diagnosis and treatment have historically taken a symptom-based approach, with less attention on identifying underlying symptom-producing mechanisms. Recent efforts have illuminated the extent to which different underlying circuitry can produce phenotypically similar symptomatology (e.g. psychosis in bipolar disorder vs schizophrenia). Computational modelling makes it possible to identify and mathematically differentiate behaviorally-unobservable, specific reinforcement-learning (RL) differences in schizophrenia (SZ) patients versus other disorders, likely due to a higher reliance on prediction-error(PE)-driven learning associated with basal ganglia, and under-reliance on explicit value representations associated with OFC.

No Abstract.