Long term objectives are to learn more about the elegant mechanisms by which highly precise, but elemental spatial and temporal information processing is carried out within VI and VII and subsequently to determine a few of the """"""""rules"""""""" by which such elemental and relatively localized descriptors are combined so that yet higher levels of the visual system can ultimately achieve spatial pattern recognition of arbitrary visual images. Further knowledge about normal visual function may help in understanding and perhaps subsequently ameliorating both innate and acquired disorders of higher visual function.
Specific aims are to study spatial and temporal information processing in VII and VIII in the macaque monkey, an animal whose visual system is very similar to that of man. Quantitative estimates of single cell selectivity will be obtained to a wide variety of stimulus dimensions including spatial position, orientation and direction of movement, spatial frequency, temporal frequency, spectral content, and binocular disparity. Microlesions will be made in order to localize recording sites to sublaminae. The results obtained will be used to address the following issues. I. Functional organization of VII. Neurons in VII differ greatly according to spatial frequency preference and the presence or absence of bandpass temporal selectivity. Do these and other response characteristics, such as contrast sensitivity, presence or absence of color opponent properties, directional selectivity and type of binocular interaction reflect a laminar or columnar organization? II. Spatial-frequency specific interactions in VII. Are there cross-frequency interactions in VII, and, if so, are these predictable on the basis of known preceding interactions in VI or will the results suggest additional, perhaps highly non-linear, processing characteristics? III. Response properties in VIII. These neurons will be studied using the same classes of stimuli described above. Additionally, tests are proposed to reveal possibly greater complexities of receptive field organization than may be present in VI and VII.
