Experiments were made in adult cats with different transections of the classical and commissural visual tracts to study evoked potentials and unit neuronal activity in response to visual stimulation. The commissural channels of the telencephalon, diencephalon and mesencephalon were demonstrated to be highly effective in visual information conduction to the visual cortex. Complete transection of the classical and commissural tracts with the exception of the commissural tract of the third ventricle fundus and midbrain reticular formation resulted in the disappearance of evoked potentials in the visual cortex in response to light flashes, despite the fact that 8 of the 15 recorded neurons responded to photostimulation. Activation of such neurons was caused by visual information conduction via two possible commissural channels: midbrain reticular formation and subventricular interhemispheric commissures of the diencephalon.