The goal of this project is to identify mechanisms of high-level visual processing in the human brain using a comprehensive set of investigative techniques. Much research has addressed the mechanisms by which the brain analyses the component features of visual images. Visual motion analysis occurs in the magnocellular retino-geniculo-cortical pathway and continues in the dorsal pathway from striate to extrastriate cortex. On the other hand, color and form analysis occurs in the parvocellular retino- geniculo-cortical pathway, and then the ventral striate to extrastriate ventral pathway. This project will determine mechanisms for convergence of dorsal and ventral analysis in the human brain. Such convergence is necessary for accurate perception and action. We will examine two """"""""cute integration"""""""" tasks: a motion tasks relying on chromatic cues, and form tasks relying on color and motion cues. We will compare these tasks to tasks that do not require such integration. We will first use psychophysical methods for determining visual thresholds for the tasks. Then, we will use functional magnetic resonance imaging to determine the brain areas of increased activation during these tasks at thresholds. Finally, we will define the temporal dynamics of neuronal processing at these brain regions using transcranial magnetic stimulation. This set of experiments will identify when and where integrated visual processing occurs in the human brain.
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