Mapping studies of the tectal representation of the frog binocular visual field. A problem of methodology.

Using the classical mapping technique, the spatio-tectal visual organization in frogs (Rana esculenta) was investigated taking special interest in the previously described existence of a "systematic disparity" between the two monocular receptive fields of rostral binocular tectal points. The existence of such a disparity was extended to the whole binocular visual field and its sign (crossed or uncrossed disparity) was studied both in paralyzed and anesthetized animals. It was proved however that this disparity phenomenon was not "systematic", but depended mainly on the experimental methodology. Its physiological significance is discussed.