The goal of this project is to develop a method of determining human brain function and structure using magnetoencephalography (MEG). We will use new methods for source localization of high resolution brain activity from MEG to determine changes in cognitive processing as people attend to tasks in specific locations in their visual field. MEG will be recorded from 60 channels at 500 Hz. The spatial resolution will be on the order of 1.5-2 cm. These measurements will be used to locate and time the activity of specific brain areas in the visual field. Our specific aims are: 1) We will examine how activity is modulated in two brain regions associated with the processing of visual information, an extrastriate visual area and the primary visual cortex, using visual attention paradigms with simple shapes. This will also permit us to develop a more sophisticated set of source localization tools. 2) We will measure activity in the fusiform gyrus as subjects attend to the color of the stimuli. Using a color discrimination task, we will examine activation of a cortical area that has been related to reading in the left hemisphere and a homologue area in the right hemisphere. The use of more natural visual stimuli will also permit us to directly measure changes in the pattern of activity as we detect and discriminate colors, rather than using a detection task with non-color stimuli. This will permit us to examine the spatial pattern of activity and to examine the possible role of top-down influences on the processing of visual information. We will also examine the role of attention in the processing of color information and the role of cognitive control in inhibiting irrelevant color information. PUBLIC HEALTH RELEVANCE: The aim of this project is to develop a method of determining human brain function and structure using magnetoencephalography (MEG). This project will use new methods for source localization of high resolution brain activity from MEG to determine changes in cognitive processing as people attend to tasks in specific locations in their visual field. MEG will be recorded from 60 channels at 500 Hz. The spatial resolution will be on the order of 1.5-2 cm. These measurements will be used to locate and time the activity of specific brain areas in the visual field. Our specific aims are: 1) We will examine how activity is modulated in two brain regions associated with the processing of visual information, an extrastriate visual area and the primary visual cortex, using visual attention paradigms with simple shapes. This will also permit us to develop a more sophisticated set of source localization tools. 2) We will measure activity in the fusiform gyrus as subjects attend to the color of the stimuli. Using a color discrimination task, we will examine activation of a cortical area that has been related to reading in the left hemisphere and a homologue area in the right hemisphere. The use of more natural visual stimuli will also permit us to directly measure changes in the pattern of activity as we detect and discriminate colors, rather than using a detection task with non-color stimuli. This will permit us to examine the spatial pattern of activity and to examine the possible role of top-down influences on the processing of visual information. We will also examine the role of attention in the processing of color information and the role of cognitive control in inhibiting irrelevant color information. [unreadable] [unreadable] [unreadable]