Attention and Visual Perception

Study Summary

The NIMH is conducting studies aimed at gaining a better understanding of the areas of the brain that are involved in different types of mental processes. This study will focus on brain regions involved in visual perception and attention. Healthy normal volunteers and people who have had a stroke or undergone neurosurgery may be eligible for this study. Candidates must be 18 years of age or older, They must not have a history of a psychiatric disorder, including depression, anxiety, psychosis, or neurological disease other than stroke or the previous neurosurgery. Participants undergo the following tests and procedures during four or more visits to the NIH Clinical Center: * Physical and neurological examinations and depression rating scale. * Cognitive testing: Subjects complete written tests, sit at a computer and make decisions about what they are shown by pressing keys, or answer questions from a test examiner. * Behavioral training: Subjects practice performing a cognitive task that involves looking at and making decisions about visual images that appear on a computer screen. * Magnetic resonance imaging (MRI): Subjects undergo MRI scanning while they perform the task they previously practiced. The MRI scanner is a metal cylinder surrounded by a strong magnetic field. During the procedure, subjects lie still for up to 10 minutes at a time on a table that can slide in and out of the cylinder. The entire MRI scanning session takes about one hour. There are multiple scans which each can take up to 10 minutes. They may be asked to return for one or two additional scanning sessions. During the behavioral training or MRI scanning, special pieces of equipment that monitor eye movements may be used. Some subjects may be asked to return to NIH for an additional visit to participate in a magnetoencephalographic scan. This test uses several sensors applied to the scalp to measure very small changes in magnetic fields. This is another way to measure brain activity.