Much is now known about the simple, passive analysis of sensory stimuli by each sensory system. However, the cognitive processes which depend on these stimuli, including learning and memory, object recognition, and integration of stimuli from several modalities, are still largely mysterious. Nor is it known how the brain combines incoming sensory information about the environment with stored information about past experience, and with information about the organism's motivational state to program appropriate behavior. The long-term goals of this research are to understand the neural mechanisms underlying perception, learning, and sensorimotor integration. The focus of the present proposal is on the contribution of visual association cortex, traditionally known as areas 18 and 19, or prestriate cortex, to these higher cognitive processes underlying behavior. In macaque monkey, an area known as """"""""V4"""""""" or the """"""""V4 complex"""""""" occupies the prelunate gyrus and adjacent buried cortex of the lunate and superior temporal sulcus. Data from visuotopic mapping studies in this region suggest that there are several topographic subdivisions. Studies of single-cell response properties suggest that the area is functionally heterogeneous.
The Aims of the present proposal are to investigate the relation between the functional mosaic and visual topography in the V4 complex, and to see if topographic subunits are distinguished by functions, connections or myeloarchitecture. Response properties of single neurons in this cortex will be studied in the awake behaving monkey. Animals will be trained on a number of different tasks, so responses of neurons in different behavioral contexts may be compared.
The first Aim i s to study classical receptive field properties of neurons.
The second Aim i s to evaluate the nature and extent of surround-mediated response modulation in these zones, to assess their contribution to object recognition.
The third Aim i s to study the effects of shifts of attention on neuronal responses. Finally, the fourth Aim is first to examine projections from V2 to two of these topographic zones, AL and PM, to see if different cell groups in V2 send input it them, and second to see if these two zones may be distinguished on the basis of myeloarchitectonics.
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