ABSTRACT
Social cognition impairments are frequently found in patients with mild traumatic brain injury (TBI) when structural lesions may not reveal the severity of the injury. Though instruments used to assess social behavior are thought to be sensitive, the absence of structural damage in TBI patients may lead to underscore such problems. The aim of this study was to develop a complementary diagnostic tool such as a paradigm for functional Magnetic resonance Imaging (fMRI) involving a simple task that could tell how patients understand certain complex social behavior by identifying different movements with or without social intentions where language and complex cognitive process were not required. Eleven patients with mild TBI and social cognition difficulties and twelve control subjects were matched by demographic variables. A paradigm of social fMRI was developed by using dots in movement representing human motion, human motion with social intention such as dancing or sharing, and dots moving without meaning. Patients had less activation in parietotemporal junction and bilateral middle frontal gyrus in the social perception task movement compared with control group subjects. The fMRI paradigm developed can be an additional diagnostic tool for identifying social cognition impairments in mild TBI patients. Regardless the absence of structural injury, changes in activation areas suggest a prospective use of this tool since clinical, cognitive and functional outcomes support such finding.
Los cambios en la cognición social son encontrados frecuentemente en pacientes con trauma craneoencefálico leve (TCE) aunque no exista evidencia de lesiones estructurales. Aunque los instrumentos utilizados para evaluar la cognición social son sensibles al cambio, la ausencia de daño estructural en los pacientes con TCE puede llevar pasar por inadvertidos estos problemas. El objetivo de este estudio fue desarrollar una herramienta diagnóstica complementaria como un paradigma para resonancia magnética funcional (RMf), la cual involucra una tarea simple que pudiera explicar cómo los pacientes entienden ciertos comportamientos sociales complejos por medio de movimientos con o sin intención social sin intermediación del lenguaje. Participaron once pacientes con TCE leve y con reporte de alteraciones en cognición social, estos fueron emparejados con doce sujetos control por variables demográficas. Un paradigma de RMf fue desarrollado por medio de la animación puntos blancos sobre una pantalla negra que representan el movimiento humano, el movimiento humano con la intención social como el baile o el compartir, y puntos que se mueven sin significado. Los pacientes tuvieron menos activación en la unión parietotemporal y giro frontal medio bilateral frente al movimiento social en comparación con los sujetos del grupo de control. El paradigma de fMRI desarrollado puede ser una herramienta de diagnóstico adicional para identificar las alteraciones cognitivas sociales en pacientes con TCE leve. Independientemente de la ausencia de lesión estructural, los cambios en las áreas de activación sugieren la posibilidad de usar esta herramienta como pronóstico dado que los resultados clínicos, cognitivos y funcionales soportan este hallazgo.
ABSTRACT
Introducción: Diversos estudios demuestran un aumento en la activación de áreas límbicas y paralímbicas y disminución de la activación en áreas relacionadas con la memoria de trabajo en pacientes con trastorno bipolar. La mayoría de estos estudios se realizan en pacientes que reciben tratamiento farmacológico, lo cual dificulta interpretar hasta qué punto el tratamiento es responsable de las alteraciones encontradas. Objetivo: Identificar las posibles diferencias en la respuesta neurofuncional de pacientes con trastorno bipolar en tareas de memoria operativa y establecer el papel de la medicación en estas diferencias. Metodología: Estudio descriptivo-correlacional de corte transversal. Se evaluaron 43 individuos, de los cuales 33 fueron pacientes eutímicos con trastorno bipolar tipo I (13 en tratamiento con carbonato de litio, 9 con ácido valpróico y 10 sin medicación al menos durante dos meses previos a la evaluación) y 11 controles. La resonancia magnética funcional (RMf) se usó para correlacionar sus procesos de memoria operativa con los cambios vistos en la señal BOLD, usando un paradigma que combina la presentación de bloques y eventos relacionados. Resultados: No se encontraron diferencias significativas en las variables clínicas o demográficas entre los grupos, excepto en el puntaje de la Young Mania Rating Scale (YMRS). Se encontraron diferencias en el patrón de activación del cíngulo anterior al comparar los pacientes bipolares y los controles (p=0,05). Conclusión: Se encontraron diferencias en el patrón de activación del cíngulo anterior en la RMf en una prueba de memoria de trabajo comparando los pacientes bipolares tipo I y los controles.
Background: Patients with bipolar disorder show increased activation in limbic and para-limbic areas whereas they show decreased activity in working memory-related areas. The degree to which pharmacological treatment determines these alterations is hard to gage, given that most studies have been done on patients already receiving such treatments. Objective: We seek to identify differences and the role of treatment in neurofunctional response in patients with bipolar disorder type I compared to controls, specifically while challenged with working memory tasks. Methods: Thirtythree euthymic patients with type I bipolar disorder and 10 controls were evaluated in a cross-sectional study; 13 of them were being treated with lithium, 9 with valproic acid, and 10 had not received treatment for at least 2 months prior to the study. Correlation was established between functional Magnetic Resonance (fMRI) BOLD signal and working memory processes. Results: There were no significant differences between the groups in demographics or clinical variables except for YMRS score. Patients and controls showed significantly different patterns of brain activation in the anterior cingulate (p:0.05) during working memory tasks. Conclusion: There are statistically significant differences in the anterior cingulate BOLD (Blood oxygen level dependent) signal of patients with Type I Bipolar disorder compared to controls.
ABSTRACT
Objective To build the linear models for exploring relations between behavior data and functional magnetic resonance image(fMRI) signals of brain during cognitive task and to validate whether it is reasonable.Methods The linear models of behavior data and fMRI signals were built,and the functional regions of brain were detected by tests of corresponding parameters.Experimental data of Stroop tasks were used to study the effects of the models by comparing with the results of SPM.Results The results of Stroop data showed that dorsal lateral prefrontal cortex(Brodmann 9/46),and superior frontal median cortex(Brodmann 8/9) were associated with response time of Stroop tasks,and accorded with SPM results and other reports.Conclusion The models can quantitatively analyze the relations of response time and fMRI signals,providing a new way to explore functional images of cognition.
ABSTRACT
PURPOSE: To investigate the brain areas related with the deficit in visuospatial attention in patients with traumatic brain injury (TBI) using functional MRI (fMRI). METHOD: Twenty TBI and fifteen normal subjects were enrolled. The endogenous visuospatial attention task was used as an activation paradigm during fMRI. FMRI was performed on a 3T ISOL Forte scanner. Thirty slices were acquired using a single-shot EPI sequences (TR/TE=3000/ 30 ms, Flip angle 70 degrees, FOV=220 mm, 64x64 matrix, slice thickness 4 mm). The accuracy and reaction time to the attention task were measured during fMRI. Imaging data were analyzed using SPM-99 software. RESULTS: The ratio of accurate responses was lower (p<0.01) and the average reaction time was slower (p<0.01) in the TBI group than the normal group. The fMRI analysis showed more activation in the bilateral prefrontal cortices (the middle and inferior frontal gyri) and less activation in the cingulate gyrus, medial frontal lobe, bilateral temporo- occipital areas, and cerebellum in the TBI group compared with the normal group. CONCLUSION: In TBI patients, impaired visuospatial attention might be resulted from the decreased activity of the cingulate, medial frontal, and temporo-occipital regions accompanied with compensatory hyperactivation of the prefrontal cortex.