Most of our comprehension of the brain functions derives from both anatomical and single neuron recording studies that somehow complete each other. In other words, we can characterize the relationships of a motor area to a typical motor behavior, such as moving our hand to reach and grasp an object. In the same way, we can fully describe the anatomical connections of this area after injecting neuroanatomical tracers.
However, what signals are conveyed specifically in a single pathway remains unknown. To determine what information cortico-cortical signals carries, the neurons that project to different areas can be identified by antidromic activation, while monkeys perform specifically designed behavioral tasks.
Our current interest is directed at the signals relayed by the callosal system, an important neural system never studied in behaving monkeys.

Neural bases of perception and action in the three-dimensional space.

The visual system extracts information about depth from a variety of cues. The presence of two eyes and the overlapped visual fields typical of primates permit measurement of binocular disparity and allow for vergence cues to depth. However, the distance of an object from the subject cannot be obtained from the horizontal relative disparity. The depth of an object indicated by a given retinal signal scales with the square of the viewing distance. Although stereo disparities are occasionally described as absolute depth cues, it is necessary to have an estimate of the vergence angle or the viewing distance to obtain either object depth or shape information from stereo information. This aspect, important for both perception and action, is often indicated as the stereo scaling problem.
In our laboratory, we are investigating the neural correlate of such aspect of the visual perception in relation to the ability to move our eyes towards targets located in the 3-D space. Controlling for vergence and disparities changes, we are recording from neurons in the lateral intraparietal area (LIP), which is well known for its relationships to spatial attention and programing and executing saccadic eye movements.

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