JOAO RICARDO SATO
Projetos de Pesquisa
Unidades Organizacionais
LIM/44 - Laboratório de Ressonância Magnética em Neurorradiologia, Hospital das Clínicas, Faculdade de Medicina
5 resultados
Resultados de Busca
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- Stroke lesion in cortical neural circuits and post-stroke incidence of major depressive episode: A 4-month prospective study(2011) TERRONI, Luisa; AMARO JR., Edson; IOSIFESCU, Dan V.; TINONE, Gisela; SATO, Joao Ricardo; LEITE, Claudia Costa; SOBREIRO, Matildes F. M.; LUCIA, Mara Cristina Souza; SCAFF, Milberto; FRAGUAS, RenerioObjective. Little is known about the relevance of lesion in neural circuits reported to be associated with major depressive disorder. We investigated the association between lesion stroke size in the limbic-cortical-striatal-pallidal-thalamic (LCSPT) circuit and incidence of major depressive episode (MDE). Methods. We enrolled 68 patients with first-ever ischemic stroke and no history of major depressive disorder. Neurological and psychiatric examinations were performed at three time-points. We diagnosed major depressive episode, following DSM-IV criteria. Lesion location and volume were determined with magnetic resonance imaging, using a semi-automated method based on the Brodmann Cytoarchitectonic Atlas. Results. Twenty-one patients (31%) experienced major depressive episode. Larger lesions in the left cortical regions of the LCSPT circuit (3,760 vs. 660 mm(3); P = 0.004) were associated with higher incidence of MDE. Secondary analyses revealed that major depressive episode was associated with larger lesions in areas of the medial prefrontal cortex including the ventral (BA24) and dorsal anterior cingulate cortex (BA32) and subgenual cortex (BA25); and also the subiculum (BA28/36) and amygdala (BA34). Conclusions Our findings indicate that depression due to stroke is aetiologically related to the disruption of the left LCSPT circuit and support the relevance of the medial prefrontal cortex dysfunction in the pathophysiology of depression.
- Wavelet correlation between subjects: A time-scale data driven analysis for brain mapping using fMRI(2011) LESSA, Patricia S.; SATO, Joao R.; CARDOSO, Elisson F.; NETO, Carlos G.; VALADARES, Ana Paula; AMARO JR., EdsonFunctional magnetic resonance imaging (fMRI) based on BOLD signal has been used to indirectly measure the local neural activity induced by cognitive tasks or stimulation. Most fMRI data analysis is carried out using the general linear model (GLM), a statistical approach which predicts the changes in the observed BOLD response based on an expected hemodynamic response function (HRF). In cases when the task is cognitively complex or in cases of diseases, variations in shape and/or delay may reduce the reliability of results. A novel exploratory method using fMRI data, which attempts to discriminate between neurophysiological signals induced by the stimulation protocol from artifacts or other confounding factors, is introduced in this paper. This new method is based on the fusion between correlation analysis and the discrete wavelet transform, to identify similarities in the time course of the BOLD signal in a group of volunteers. We illustrate the usefulness of this approach by analyzing fMRI data from normal subjects presented with standardized human face pictures expressing different degrees of sadness. The results show that the proposed wavelet correlation analysis has greater statistical power than conventional GLM or time domain intersubject correlation analysis.
- How Doctors Generate Diagnostic Hypotheses: A Study of Radiological Diagnosis with Functional Magnetic Resonance Imaging(2011) MELO, Marcio; SCARPIN, Daniel J.; AMARO JR., Edson; PASSOS, Rodrigo B. D.; SATO, Joao R.; FRISTON, Karl J.; PRICE, Cathy J.Background: In medical practice, diagnostic hypotheses are often made by physicians in the first moments of contact with patients; sometimes even before they report their symptoms. We propose that generation of diagnostic hypotheses in this context is the result of cognitive processes subserved by brain mechanisms that are similar to those involved in naming objects or concepts in everyday life. Methodology and Principal Findings: To test this proposal we developed an experimental paradigm with functional magnetic resonance imaging (fMRI) using radiological diagnosis as a model. Twenty-five radiologists diagnosed lesions in chest X-ray images and named non-medical targets (animals) embedded in chest X-ray images while being scanned in a fMRI session. Images were presented for 1.5 seconds; response times (RTs) and the ensuing cortical activations were assessed. The mean response time for diagnosing lesions was 1.33 (SD +/- 0.14) seconds and 1.23 (SD +/- 0.13) seconds for naming animals. 72% of the radiologists reported cogitating differential diagnoses during trials (3.5 seconds). The overall pattern of cortical activations was remarkably similar for both types of targets. However, within the neural systems shared by both stimuli, activation was significantly greater in left inferior frontal sulcus and posterior cingulate cortex for lesions relative to animals. Conclusions: Generation of diagnostic hypotheses and differential diagnoses made through the immediate visual recognition of clinical signs can be a fast and automatic process. The co-localization of significant brain activation for lesions and animals suggests that generating diagnostic hypotheses for lesions and naming animals are served by the same neuronal systems. Nevertheless, diagnosing lesions was cognitively more demanding and associated with more activation in higher order cortical areas. These results support the hypothesis that medical diagnoses based on prompt visual recognition of clinical signs and naming in everyday life are supported by similar brain systems.
- Identification of psychopathic individuals using pattern classification of MRI images(2011) SATO, Joao R.; OLIVEIRA-SOUZA, Ricardo de; THOMAZ, Carlos E.; BASILIO, Rodrigo; BRAMATI, Ivanei E.; AMARO JR., Edson; TOVAR-MOLL, Fernanda; HARE, Robert D.; MOLL, JorgeBackground: Psychopathy is a disorder of personality characterized by severe impairments of social conduct, emotional experience, and interpersonal behavior. Psychopaths consistently violate social norms and bring considerable financial, emotional, or physical harm to others and to society as a whole. Recent developments in analysis methods of magnetic resonance imaging (MRI), such as voxel-based-morphometry (VBM), have become major tools to understand the anatomical correlates of this disorder. Nevertheless, the identification of psychopathy by neuroimaging or other neurobiological tools (e. g., genetic testing) remains elusive. Methods/Principal findings: The main aim of this study was to develop an approach to distinguish psychopaths from healthy controls, based on the integration between pattern recognition methods and gray matter quantification. We employed support vector machines (SVM) and maximum uncertainty linear discrimination analysis (MLDA), with a feature-selection algorithm. Imaging data from 15 healthy controls and 15 psychopathic individuals (7 women in each group) were analyzed with SPM2 and the optimized VBM preprocessing routines. Participants were scanned with a 1.5 Tesla MRI system. Both SVM and MLDA achieved an overall leave-one-out accuracy of 80%, but SVM mapping was sparser than using MLDA. The superior temporal sulcus/gyrus (bilaterally) was identified as a region containing the most relevant information to separate the two groups. Conclusion/significance: These results indicate that gray matter quantitative measures contain robust information to predict high psychopathy scores in individual subjects. The methods employed herein might prove useful as an adjunct to the established clinical and neuropsychological measures in patient screening and diagnostic accuracy.
- Brain activity patterns during phonological verbal fluency performance with varying levels of difficulty: A functional magnetic resonance imaging study in Portuguese-speaking healthy individuals(2011) SENHORINI, Maurien C. T.; CERQUEIRA, Carlos T.; SCHAUFELBERGER, Maristela S.; ALMEIDA, Jorge C.; AMARO, Edson; SATO, Joao R.; BARREIROS, Maria A. M.; AYRES, Adriana M.; CASTRO, Claudio C.; SCAZUFCA, Marcia; MENEZES, Paulo R.; BUSATTO, Geraldo F.A large number of functional neuroimaging studies have investigated the brain circuitry which is engaged during performance of phonological verbal fluency tasks, and the vast majority of these have been carried out in English. Although there is evidence that this paradigm varies depending on the language spoken, it is unclear if this difference is associated with differences in brain activation patterns. Also, there is neuroimaging evidence that the patterns of regional cerebral activation during verbal fluency tasks may vary with the level of task demanded. In particular, the engagement of the anterior cingulate cortex seems to be relative to cognitive demand. We compared functional magnetic resonance imaging data in healthy Portuguese-speaking subjects during overt production of words beginning with letters classified as easy or hard for word production in Portuguese. Compared to the baseline condition, the two verbal fluency tasks (with either easy or hard letters) engaged a network including the left inferior and middle frontal cortices, anterior cingulate cortex, putamen, thalamus and cerebellum (p < .001). The direct comparison between the two verbal fluency conditions showed greater cerebellar activation in the easy condition relative to the hard condition. In the anterior cingulate cortex, there was a direct correlation between activity changes and verbal fluency performance during the hard condition only. Despite grammatical differences, the changes in patterns of brain activity during verbal fluency performance observed in our study are in accordance with findings of previous neuroimaging studies of verbal fluency carried out in English and other languages, with recruitment of a set of distributed cerebral areas during word production.