Kathleen S. Rockland - Böcker

Volume 10 is a direct continuation and extension of Volume 3 in this series, Visual Cortex. Given the impressive proliferation of papers on visual cortex over the intervening eight years, Volume 10 has specifically targeted visual cortex in primates and, even so, it has not been possible to survey all of the major or relevant developments in this area. Some research areas are experiencing rapid change and can best be treated more comprehensively in a subsequent volume; for example, elaboration of color vision; patterns and subdivisions of functional columns. One major goal of this volume has been to provide an overview of the intrinsic structural and functional aspects of area 17 itself. Considerable pro­ gress has been made since 1985 in unraveling the modular and laminar organi­ zation of area 17; and this aspect is directly addressed in the chapters by Peters, Lund et al., Wong-Riley, and Casagrande and Kaas. A recurring leitmotif here is the evidence for precise and exquisite order in the interlaminar and tangential connectivity of elements. At the same time, however, as detailed by Lund et al. and Casagrande and Kaas, the very richness of the connectivity implies a multi­ plicity of processing routes. This reinforces evidence that parallel pathways may not be strictly segregated. Further connectional complexity is contributed by the various sets of inhibitory neurons, as reviewed by Lund et al. and Jones et al.

Over the last twenty-five years, there has been an extensive effort, still growing for that matter, to explore and understand the organization of extrastriate cor­ tex in primates. We now recognize that most of caudal neocortex is visual in some sense and that this large visual region includes many distinct areas. Some of these areas have been well defined, and connections, neural properties, and the functional consequences of deactivations have been studied. More recently, non­ invasive imaging of cortical activity patterns during visual tasks has led to an expanding stream of papers on extrastriate visual cortex of humans, and results have been related to theories of visual cortex organization that have emerged from research on monkeys. Against this backdrop, the time seems ripe for a review of progress and a glance at the future. One caveat important to emphasize at the very onset is that the reader may be puzzled or confused by the use of different terminologies. Individual investi­ gators commonly tend to favor different terminologies, but in general some prove more advantageous than others. As discussed by Rowe and Stone (1977) as well as by others, there is an unfortunate tendency for role-indicating names to lead to fixed ideas about function, in contrast to those that are more neutral and adaptable to new findings.

Over the last twenty-five years, there has been an extensive effort, still growing for that matter, to explore and understand the organization of extrastriate cor­ tex in primates. We now recognize that most of caudal neocortex is visual in some sense and that this large visual region includes many distinct areas. Some of these areas have been well defined, and connections, neural properties, and the functional consequences of deactivations have been studied. More recently, non­ invasive imaging of cortical activity patterns during visual tasks has led to an expanding stream of papers on extrastriate visual cortex of humans, and results have been related to theories of visual cortex organization that have emerged from research on monkeys. Against this backdrop, the time seems ripe for a review of progress and a glance at the future. One caveat important to emphasize at the very onset is that the reader may be puzzled or confused by the use of different terminologies. Individual investi­ gators commonly tend to favor different terminologies, but in general some prove more advantageous than others. As discussed by Rowe and Stone (1977) as well as by others, there is an unfortunate tendency for role-indicating names to lead to fixed ideas about function, in contrast to those that are more neutral and adaptable to new findings.