Brain activation patterns during a verbal fluency test - A functional MRI study in healthy volunteers and patients with schizophrenia
Department of Biological Psychiatry, Innsbruck University Clinics, Anichstrasse 35, 6020 Innsbruck, Austria. Schizophrenia Research
(Impact Factor: 3.92).
11/2004; 70(2-3):287-91. DOI: 10.1016/j.schres.2004.01.010
FMRI was used to study cortical activation patterns in nine healthy male subjects and nine high-functioning male schizophrenia patients during a letter verbal fluency task. Both groups showed similar patterns of activation, however, in controls the activation was primarily in the left broca area, while for schizophrenia patients, it was more bilateral. These data indicate that high-functioning schizophrenia patients show a reduced language lateralization of the frontal cortex compared to healthy controls.
- "These areas comprise left Broca's area, which is a brain region primarily involved in speech production. Previous functional MRI studies compared the cortical activation patterns in patients with schizophrenia and healthy controls during the letter VFT (Weiss et al., 2004). Their results indicated that the activation in healthy controls was primarily located in the left Broca's area, whereas for schizophrenia patients, it was more bilateral. "
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ABSTRACT: Based on near-infrared spectroscopy (NIRS), recent converging evidence has been observed that patients with schizophrenia exhibit abnormal functional activities in the prefrontal cortex during a verbal fluency task (VFT). Therefore, some studies have attempted to employ NIRS measurements to differentiate schizophrenia patients from healthy controls with different classification methods. However, no systematic evaluation was conducted to compare their respective classification performances on the same study population.
In this study, we evaluated the classification performance of four classification methods (including linear discriminant analysis, k-nearest neighbors, Gaussian process classifier, and support vector machines) on an NIRS-aided schizophrenia diagnosis. We recruited a large sample of 120 schizophrenia patients and 120 healthy controls and measured the hemoglobin response in the prefrontal cortex during the VFT using a multichannel NIRS system. Features for classification were extracted from three types of NIRS data in each channel. We subsequently performed a principal component analysis (PCA) for feature selection prior to comparison of the different classification methods.
We achieved a maximum accuracy of 85.83% and an overall mean accuracy of 83.37% using a PCA-based feature selection on oxygenated hemoglobin signals and support vector machine classifier.
This is the first comprehensive evaluation of different classification methods for the diagnosis of schizophrenia based on different types of NIRS signals.
Our results suggested that, using the appropriate classification method, NIRS has the potential capacity to be an effective objective biomarker for the diagnosis of schizophrenia.
Copyright © 2014. Published by Elsevier B.V.
- "With structural magnetic resonance imaging (MRI), converging evidences have revealed the structural changes of prefrontal cortex in schizophrenia including brain volume atrophy (Steen et al., 2006), cortical thickness thinning (Narr et al., 2005) and gyrification reduction (Palaniyappan et al., 2011). In addition, more and more studies have utilized functional neuroimaging technologies, e.g., functional MRI (fMRI), to investigate brain functional activation during the resting state (Lynall et al., 2010) as well as various cognitive tasks (Weiss et al., 2004). These results provided us imaging observation on the dysfunction of prefrontal cortex in patients with schizophrenia. "
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ABSTRACT: Near-infrared spectroscopy (NIRS) has been applied to examine the possible functional alternations during the performance of cognitive tasks in schizophrenia. With this technique, previous studies have observed that patients with schizophrenia are often associated with reduced brain activations in the prefrontal cortex during the verbal fluency task (VFT) of English version or Japanese version. However, it remains unclear whether there are the brain functional impairment for Chinese-speaking patients with schizophrenia. In this study, we designed a Chinese version VFT and performed a multichannel NIRS study in a large group of patients with schizophrenia and healthy controls. We investigated the brain activations during the task period of the Chinese version VFT within schizophrenia group and healthy group, respectively, and compared their relative changes between two groups. Our results confirmed that Chinese-speaking patients with schizophrenia had the significant lower brain activations in the prefrontal cortex and superior temporal cortex when compared with healthy controls. Such findings based on NIRS data provided us the reliable evidences about the brain functional deficits in Chinese-speaking patients with schizophrenia.
Copyright © 2014. Published by Elsevier Inc.
Available from: Pascal Vianin
- "Numerous functional magnetic resonance imaging (fMRI) studies showed that covert letter verbal fluency is mainly associated with the left frontal cortex, corresponding to Broca 0 s area in healthy subjects (McGraw et al., 2001). Compared with healthy controls, individuals with schizophrenia showed a lower level of frontal response during a covert verbal fluency task (Yurgelun-Todd et al., 1996; Weiss et al., 2004). We expected therefore that verbal mediation techniques should lead to an increased activation of Broca 0 s area and a better level of executive functioning after cognitive training. "
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ABSTRACT: Functional magnetic resonance imaging (fMRI) was used to measure changes in cerebral activity in patients with schizophrenia after participation in the Cognitive Remediation Program for Schizophrenia and other related disorders (RECOS). As RECOS therapists make use of problem-solving and verbal mediation techniques, known to be beneficial in the rehabilitation of dysexecutive syndromes, we expected an increased activation of frontal areas after remediation. Executive functioning and cerebral activation during a covert verbal fluency task were measured in eight patients with schizophrenia before (T1) and after (T2) 14 weeks of RECOS therapy. The same measures were recorded in eight patients with schizophrenia who did not participate in RECOS at the same intervals of time (TAU group). Increased activation in Broca's area, as well as improvements in performance of executive/frontal tasks, was observed after cognitive training. Metacognitive techniques of verbalization are hypothesized to be the main factor underlying the brain changes observed in the present study.
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