New images from human visual cortex.

Recent developments in imaging and histology have greatly clarified our understanding of the nature and organization of human visual cortex. More than ten human cortical visual areas can now be differentiated, compared with the approximately 30 areas described in macaque monkeys. Most human areas and columns described so far appear quite similar to those in macaque but distinctive species differences also exist. Imaging studies suggest two general information-processing streams (parietal and temporal) in human visual cortex, as proposed in macaque. Several human areas are both motion- and direction-selective, and a progression of motion-processing steps can be-inferred from the imaging data. Human visual areas for recognizing form are less well defined but the evidence again suggests a progression of information-processing steps and areas, beginning posterior to the human middle temporal area (or V5), and extending inferiorly then anteriorly. This is consistent with findings from macaque, and with human clinical reports.