Influences Of Posteromedial Lateral Suprasylvian Motion Area And 21a Form Area On The Orientation Preference And Direction Preference In The Primary Visual Cortex Of Cats

In visual cortices of high mammals such as cats and monkeys there are two major, largely parallel, 'feedforward' processing streams which carry visual information from the primary visual cortices respectively to the parietal and temporal visual cortices. In the present study, using the optical imaging technique based on intrinsic signals combined with pharmacological methods, we examined the influence of 'feedback' signals both from the posteromedial lateral suprasylvian (PMLS) area which is a dominant motion processing region and area 21a which is a dominant form processing region on the responsiveness of neurons and 'orientational and directional maps' in area 17 (striate cortex, area V1). Despite the fact that area 17, unlike area PMLS, is mainly involved in the form/pattern rather than motion-processing, the reversible deactivation of both area PMLS and area 21a resulted in the reduction of the magnitude of responses of area 17 cells. Furthermore, whereas inactivation of area PMLS did not affect the basic structure of the 'orientation maps' in area 17, deactivation of area PMLS virtually abolished the global layout of 'direction maps' in area 17. By contrast, inactivation of area 21a did affect partial structure of the 'orientation maps' in area 17. In addition, the feedback functions of both area PMLS and area 21a had somehow specificity. Thus, it appears that higher-order cortical areas in one information processing stream may exert differential modulatory effects on fundamental properties of neurons located in the lower-order areas of another information processing stream.