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Role of the Brain in Processing Visually Presented Objects

Role of the Parieto-Frontal Network in Automatic Processing of Visually Presented Objects

This study will examine the parts of the brain that use visual information to perform movements. Patients with certain brain lesions tend to have difficulty in processing visually presented objects. This study will look at the brain mechanisms underlying the visuo-motor integration.

Healthy normal volunteers between 20 and 60 years of age are eligible for this study. People who have had a severe head injury with loss of consciousness or any other mental or neurological disorder diagnosed by a doctor may not participate. Candidates will be screened with a medical history, a physical examination focusing on finger movements, and a questionnaire.

Participants' brain activity will be recorded using two techniques - magnetoencephalography(MEG) and magnetic resonance imaging (MRI) - while they watch pictures of various objects flashed on a screen. MEG is a procedure to record magnetic field changes produced by brain activity. During the recording, the subject sits comfortably in an armchair in a dimly lit room and watches pictures presented on a screen. About 50 pictures are shown per session. There are about five sessions, separated by 3-minute breaks. Functional MRI involves taking pictures of the brain using MRI while the subject performs a task. MRI uses a strong magnetic field and radio waves to obtain images of body organs and tissues. The MRI scanner is a metal cylinder surrounded by a magnetic field. The subject lies still on a table that can slide in and out of the scanner. During the scan, he or she looks at pictures in six test blocks of 1 minute each, with 30-second breaks between blocks.

Descripción general del estudio

Estado

Terminado

Descripción detallada

Objectives: Patients with frontal lobe lesions tend to grasp visually presented objects automatically and forcefully (forced grasping). Grasping of a milder form is seen in infants and the aged population. These facts suggest the presence of an inherent mechanism for suppressing the automatic tendency toward grasping in the healthy adult brain. Previous studies suggest that the parieto-frontal network, especially the lateral premotor cortex, play a role in the cognition of graspable objects and execution of reaching/grasping. Although the task of reaching/grasping in human beings has been studied mainly by neuroimaging techniques, its cognitive and executive aspects have not been clearly distinguished. Therefore, this project aims to elucidate the mechanisms underlying 'automatic grasping' in humans, focusing on the perceptive/cognitive aspect of the reaching/grasping movements.

Study population and design: Pictures of graspable objects and non-graspable objects are visually presented to 45 healthy adult volunteers. Since this study aims to clarify the mechanism of the human brain for automatically recognizing graspable objects, part of this study will require no response task. Additionally, in order to assess how the automatic functions compare to overt mechanisms, an extra testing session will explore making overt judgments of the pictures.

Outcome measures: The brain activations are investigated by event-related magnetic fields, which have high temporal resolution, and by event-related functional magnetic resonance imaging (fMRI), which has relatively high spatial resolution. It is expected that the lateral premotor cortex, in addition to the parietal cortex, is activated by the visual presentation of graspable objects at a shorter latency, and more strongly, as compared with non-graspable objects, even without any actual motor tasks to follow. Additionally, overt grasping of graspable objects will involve similar areas.

Tipo de estudio

De observación

Inscripción

45

Contactos y Ubicaciones

Esta sección proporciona los datos de contacto de quienes realizan el estudio e información sobre dónde se lleva a cabo este estudio.

Ubicaciones de estudio

    • Maryland
      • Bethesda, Maryland, Estados Unidos, 20892
        • National Institutes of Health Clinical Center, 9000 Rockville Pike

Criterios de participación

Los investigadores buscan personas que se ajusten a una determinada descripción, denominada criterio de elegibilidad. Algunos ejemplos de estos criterios son el estado de salud general de una persona o tratamientos previos.

Criterio de elegibilidad

Edades elegibles para estudiar

20 años a 60 años (Adulto)

Acepta Voluntarios Saludables

Géneros elegibles para el estudio

Todos

Descripción

  • INCLUSION CRITERIA:

Healthy male or female subjects between the ages of 20 and 60 years old will be eligible within the limits of the exclusion criteria below.

EXCLUSION CRITERIA:

A previous history of neurological diseases will be carefully taken by direct interview by the Principal or Associate Investigators. Subjects who had a head injury (severe enough to cause loss of consciousness) or other brain diseases causing mental disturbance, sensory impairment, or motor dysfunction in the past will be excluded. Subjects who have metals either in the mouth, such as dental prostheses, or in the head, such as surgical clips from any previous surgical procedures, are also excluded due to technical limitations in terms of MEG. Furthermore, subjects wearing glasses for visual correction and those with poor vision, even with contact lenses, are excluded also due to technical limitations for MEG. Subjects who have pacemakers or other implanted electrical devices, brain stimulators, dental implants, aneurysm clips (metal clips on the wall of a large artery), metallic prostheses (including metal pins and rods, heart valves, and cochlear implants), permanent eyeliner, implanted delivery pump, or shrapnel fragments, and welders and metal workers are excluded for MRI for the sake of safety of subjects. Finally, by doing a brief neurological examination of finger movements, the subjects with poor performance of fine finger movements or those who are judged to have mirror movements will be excluded.

Plan de estudios

Esta sección proporciona detalles del plan de estudio, incluido cómo está diseñado el estudio y qué mide el estudio.

¿Cómo está diseñado el estudio?

Colaboradores e Investigadores

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Publicaciones y enlaces útiles

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Fechas de registro del estudio

Estas fechas rastrean el progreso del registro del estudio y los envíos de resultados resumidos a ClinicalTrials.gov. Los registros del estudio y los resultados informados son revisados ​​por la Biblioteca Nacional de Medicina (NLM) para asegurarse de que cumplan con los estándares de control de calidad específicos antes de publicarlos en el sitio web público.

Fechas importantes del estudio

Inicio del estudio

18 de noviembre de 2003

Finalización del estudio

28 de octubre de 2008

Fechas de registro del estudio

Enviado por primera vez

26 de julio de 2006

Primero enviado que cumplió con los criterios de control de calidad

26 de julio de 2006

Publicado por primera vez (Estimar)

27 de julio de 2006

Actualizaciones de registros de estudio

Última actualización publicada (Actual)

2 de julio de 2017

Última actualización enviada que cumplió con los criterios de control de calidad

30 de junio de 2017

Última verificación

28 de octubre de 2008

Más información

Términos relacionados con este estudio

Otros números de identificación del estudio

  • 040047
  • 04-N-0047

Esta información se obtuvo directamente del sitio web clinicaltrials.gov sin cambios. Si tiene alguna solicitud para cambiar, eliminar o actualizar los detalles de su estudio, comuníquese con register@clinicaltrials.gov. Tan pronto como se implemente un cambio en clinicaltrials.gov, también se actualizará automáticamente en nuestro sitio web. .

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