HYPOTHESIS: The hypothesis of this study is that the parieto-frontal network is activated by visuomotor behavior in humans. OBJECTIVES: To detect frontal and parietal cortical activity during a visuomotor task with frequency modulated visual stimuli using magnetoencephalography (MEG). To reveal how the parieto-frontal activities change according to different conditions of attention, gaze, and motor output. STUDY POPULATION: Right handed normal volunteers with no known history of neurological or ophthalmological diseases will be recruited to participate in this study. DESIGN: This study is a combination of a frequency tagging method and an MEG. Visual stimuli are presented, flickering in specific (tagged) frequencies. The cortical distribution of the visual information is estimated from the tagged frequency response of the MEG signal. We will use a visuomotor tracking task with a multifactorial task design (attention, target motion, position in retinal coordinate, and manual tracking) to evaluate the effect of each factor separately. OUTCOME MEASURES: We will use the adaptive linear-filter technique known as synthetic aperture magnetometry (SAM) to estimate the source location and strength of the tagged frequencies. The estimated cortical source activity power at the frontal and parietal cortices will be group analyzed with multiple logistic models and by analysis of variance (ANOVA) with correction for multiple comparisons.
* INCLUSION CRITERIA: The subjects must be 20 years old or older and right-handed as screened by Edinburgh handedness inventory. They must be healthy and have no known history of neurological or ophthalmological diseases. EXCLUSION CRITERIA: Subjects under the age of 20 will be excluded from this study. Subjects who match the criteria below will be excluded from this study due to human subject protection and because they may negatively affect the MEG data quality. Subjects wearing glasses. Subjects with involuntary movement or dyskinesia. Subjects with spontaneous nystagmus. Subjects who can not execute the eye or manual tracking after sufficient practice time. Subjects with metal objects in the body. Subjects with history of severe head trauma. Pregnant women.