FIBER GROUPS IN PRIMARY OPTIC PATHWAY OF CAT

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Abstract
Antidromic action potentials of the optic nerve produced by single shock electrical stimulation of the optic tract show that the primary optic pathway consists of 3 groups of fibers conducting at velocities of 70 m , 30 m and 17m /sec. respectively. They are, however, not equally and evenly distributed in the optic tracts on both sides. The 1st and the 2d groups are dominant in the uncrossed tract, with the 1st distributed more deeply than the 2d. The group III fibers are negligibly few. In the crossed tract, fibers belonging to the 3d group are more superficially distributed than the medium-sized fibers, and the group I fibers are present throughout the tract, the highest concentration occurring in the central region. The superior colliculus seems to receive only the large fibers. No interconnection between the 2 tracts is indicated by the action potential.