Neural mechanisms of top-down selection during visual search

The brain´s representation of visual information depends greatly on the behavioral relevance of the viewed stimuli. While in some instances behavioral significance is derived from conspicuity, in many situations significance depends on top-down factors such as the viewer´s goals and knowledge. Studies combining neural recordings and behavioral observations have begun to elucidate how the brain selects visual stimuli based on top-down information. While many visual areas of the brain that are selective for visual attributes participate in the selection process, the outcome of the selection process across these areas appears to be represented in structures like the frontal eye field, a key stage in the transformation of visual selection into a command to move the eyes. Evidence shows that the frontal eye field exhibits all the characteristics of a visual salience map in which the behavioral significance of stimuli derived from bottom-up and top-down influences is represented. The patterns of neural modulation in structures like the frontal eye field can be used to design more efficient machine-vision algorithms for target selection