My research interest is to understand how subjective perception and voluntary motor actions emerge from brain activity. My main approach is to record neural activity in the brains of monkeys performing various visual search and forced-choice discrimination tasks. Most of my research has focused on the frontal eye field, which is located in the prefrontal cortex and participates in the transformation of visual information into commands to move the eyes. The goal this project is to understand how we make perceptual decisions, choose where to direct gaze and to understand the neural basis of directed visual attention. The results of our experiments demonstrate that the frontal eye field functions as a visual salience map, a topographic representation of the relative importance of every object in the visual scene, for the purpose guiding attention and eye movements (reviewed in ref. 1). We hypothesize that the salience map in the frontal eye field corresponds to the salience map featured in many theoretical models of directed spatial attention and saccade target selection. As predicted by the theoretical models, we showed that the pattern of activity across the frontal eye field not only identifies the target of the next saccade, but also corresponds to the behavioral probability of making a saccade choice in visual search tasks with varying difficulty (ref. 2). This is accomplished by integrating the bottom-up physical salience present in the visual scene with the top-down knowledge and goals of the viewer (ref. 2). One of the outstanding questions of cognitive neuroscience is how we are able to focus visual attention on specific objects and locations without moving our eyes. Multiple lines of evidence suggest that the spatially selective activity in the frontal eye field that precedes saccades is dissociated from the production of eye movements (reviewed in ref. 3). We have extended this evidence to show that the activity of visually responsive neurons in the frontal eye field, but not saccade related movement neurons, corresponds to the locus of covert spatial attention without any evidence of saccade planning (ref. 4). These studies have extended our understanding about the frontal eye field far beyond its familiar role in controlling eye movements. With this knowledge we can design experiments to investigate the flow of sensory information through the brain as it is transformed into perception and action. This work helps us understand the mechanisms of how the brain focuses attention to make perceptual decisions and guide behavior, which is necessary to be able to understand and treat attention-related disorders in humans.
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