Three-dimensional object processing in the primate brain.

We live in a three-dimensional world, but the retinal image is two-dimensional. Our brain has to reconstruct the third dimension from a variety of depth cues. One of the most powerful depth cues is binocular disparity, which arises from the slight differences between the images in the left and the right eye. The current proposal wants to investigate the neural processing of three-dimensional (3D) shape in the primate brain. We want to study how the brain transforms sensory information about 3D shape into motor commands by recording in the prefrontal cortex (PFC) – the highest control level in the brain – while monkeys judge whether a stimulus presented on a display is either convex or concave. To determine whether the activity in the prefrontal cortex is related to the perceptual decisions of the animal, we will measure the correlation between the firing rate and the report of the monkeys, and electrically stimulate clusters of PFC neurons during the decision process in order to bias the choices of the animals in a predictable way. This proposal also seeks to investigate the neural machinery involved in transforming 3D object information into grasping actions: what do neurons in parietal and premotor cortex encode when viewing graspable objects or images of objects, and how is visual object information used to adapt the grip when the object is perturbed? The results obtained in this project will shed light on the process of visuomotor transformations, one of the most fascinating achievements of our brain.