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... Attenuated anterior cingulate response in schizophrenia has been shown during monitoring of performance using the Continuous Performance Test (CPT) (Ref. 40). This test involves presentation of a random sequence of stimuli over an extended period of time which subjects monitor for targets. ...
... This new class of imaging experimental designs exploits the temporal resolution of fMRI by modelling signal changes associated with single behavioural trials as opposed to blocks of trials. Its use in the study of schizophrenia is already emerging 37,40 , and when event-related fMRI is fully exploited, fMRI could supersede PET in the advances made to our knowledge of schizophrenia. Advantages of this method include the ability to (1) randomize trial presentations, (2) test for functional correlates of behavioural measures with greater power, (3) directly examine the neural correlates of behavioural trials, and (4) test for differences in the onset time of neural activity evoked by different trial types. ...
Despite being one of the most prevalent psychiatric conditions, SCHIZOPHRENIA is still poorly understood, with no clear objective biological marker. The advent of neuroimaging has enabled in vivo investigations to complement older techniques, and has revealed important insights. fMRI provides a means to assess the neurobiological theory that schizophrenia is caused by abnormal fronto-temporal lobe connections. In studies of language abnormalities, fMRI can explicitly assess the hypothesis that the normal lateralization of language is reversed in schizophrenia. Longitudinal fMRI studies, and studies examining the effects of medication, suggest that the technique has further potential to advance our understanding of this complex disorder.
... Within this model errors are considered to reflect high states of response competition, as activity associated with the incorrect response competes with activation of the correct response during ongoing stimulus evaluation during and immediately after execution of the error. It has been hypothesized that a disturbance in the function of the anterior cingulate cortex is related to impaired cognition and disorganization in schizophrenia, and initial studies using ERP (Kopp and Rist 1999;Mathalon et al. 2000) and fMRI (Carter et al. 1999) appear to support this hypothesis, by showing reduced error-related activity in this brain region. Carter et al. (1997) showed reduced activation associated with response competition in a heterogeneous, chronic medicated group of patients, while the correlation with errors, in the face of an increased error rate, was preserved. ...
... Increased activity associated with increased error rates could reflect either an intact system, or one that is impaired compared with normals but nonetheless still responsive to some degree to errors. In addition, to the degree that impaired performance monitoring would be associated with impaired modulation of executive functions and disorganization (Carter et al. 1999), the paranoid patients in the current study would be the least likely of any group of schizophrenia patients to show such an impairment. It would be important for future studies to examine unmedicated patients with a range of symptomatology using event-related imaging methods to address the degree to which impaired performance monitoring by the anterior cingulate cortex is relevant to cognitive dysfunction in schizophrenia. ...
Unlabelled:
Using [O-15]-H(2)O PET Carter et al. (1997) reported that medicated patients with schizophrenia performing computerized single trial Stroop (1935) showed a reduction in the anterior cingulate activation response to the more attention demanding, incongruent Stroop condition. In that study, both patients and controls also showed a direct correlation between anterior cingulate activation and errors committed during incongruent trials of the task. In this study we follow up with an examination of paranoid schizophrenia outpatients and controls with very high resolution positron emission tomography (PET) and the longer half-life tracer [F-18]-fluorinated deoxyglucose (FDG) (Valk et al. 1990). All subjects (10 controls and 9 paranoid schizophrenia patients) were studied with FDG-PET while performing a computerized trial-by-trial version of the Stroop task during the uptake phase of the tracer (Carter et al. 1992).
Results:
As in previous studies using the single trial Stroop, patients were able to perform the task but made more color-naming errors during incongruent trials than controls. The patients in the present study showed a trend towards increased metabolic activity in the right anterior cingulate cortex. In the patient group, but not in controls, the anterior cingulate glucose metabolic rate correlated positively with the total incongruent trial errors.
Conclusion:
These results are consistent with the hypothesis that the anterior cingulate plays a performance-monitoring role during human cognition. This study does not rule out a reduction in error sensitivity in this region of the brain in schizophrenia, as other studies have suggested, however the data show that in unmedicated patients with the paranoid subtype this function is preserved to some extent.
... Of interest, these studies evaluated both the graymatter and white-matter regions of the ACC. Functional abnormalities in the ACC brain region have been associated with schizophrenia; these changes commonly involve altered cognition, including executive control and attention [99][100][101][102]. The involvement of the ACC white and gray matter in schizophrenia is becoming more apparent with the findings of structural, genetic and morphological changes in schizophrenia [103][104][105]. ...
While proteomics has excelled in several disciplines in biology (cancer, injury and aging), neuroscience and psychiatryproteomic studies are still in their infancy. Several proteomic studies have been conducted in different areas of psychiatric disorders, including drug abuse (morphine, alcohol and methamphetamine) and other psychiatric disorders (depression, schizophrenia and psychosis). However, the exact cellular and molecular mechanisms underlying these conditions have not been fully investigated. Thus, one of the primary objectives of this review is to discuss psychoproteomic application in the area of psychiatric disorders, with special focus on substance- and drug-abuse research. In addition, we illustrate the potential role of degradomic utility in the area of psychiatric research and its application in establishing and identifying biomarkers relevant to neurotoxicity as a consequence of drug abuse. Finally, we will discuss the emerging role of systems biology and its current use in the field of neuroscience and its integral role in establishing a comprehensive understanding of specific brain disorders and brain function in general.
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