Disorders of higher cortical visual function.

In the past few years, there have been significant advances in the understanding of how the so-called higher cortical functions are organized and mapped into various anatomic brain regions. There has been considerable refinement in lesion localization provided by magnetic resonance imaging (MRI), so the precise regions that are damaged in patients with particular types of visual perceptual problems can be demonstrated. In addition, functional MRI has provided insight into neural networks serving higher cortical functions in normal human subjects as they perform perceptual and cognitive tasks.