The aim of this study is to define the functional neuroanatomy of brain regions subserving the control of eye movements in humans at high spatial resolution with fMRI. Single-cell recording studies in nonhuman primates during performance of saccadic eye movement tasks have found increased activation in cortical regions including the frontal eye fields, supplementary motor area, posterior parietal cortex and dorsolateral prefrontal cortex, as well as in several subcortical structures. In humans, a small number of PET, fMRI, stroke and lobectomy studies provide evidence for a generally similar mapping of the eye movement control system in humans. However, detailed delineation of the functional anatomy of this circuitry, and discrimination of the unique computational activities performed by its component structures, has not yet been achieved in humans. Using high-field echo-planar fMRI, established behavioral tasks, and stimulus-synchronized MR image analysis, we will undertake studies to characterize this neuronal network at unprecedented spatial and temporal resolution.
The specific aims are to: 1) establish the functional neuroanatomy of reflexive saccadic eye movements, including efforts to characterize inter-and intra-subject consistency of activations, 2) differentiate task-related activations in specific brain regions during particular task conditions (e.g. pursuit vs. saccades, small vs. large saccades, reflexive vs. voluntary saccades) and 3) develop novel methodologies for using the temporal resolution of fMRI for characterizing time courses of activation effects and functional connectivity in vivo. These studies were designed to address important questions about elementary cognitive processes and oculomotor control systems in humans, and to lay the groundwork for fMRI studies of clinical disorders associated with eye movement abnormalities.
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