 Abstract: Ivane Beritashvili was one of major figures in 20th Century neuroscience. Mastering the string galvanometer, he founded the electrophysiology of spinal cord reflexes, showing that inhibition is a distinctly different process from excitation (1916). Since 1930s Beritashvili carried out brilliant experiments on animal behavior. He revealed the unique nature of mammalian memory processes, which he forthrightly called “image driven”, and distinguished them unequivocally from those underlying conditional reflexes. Before World War II Beritashvili began an extraordinary line of experimentation that, figuratively, ultimately provided the giant’s shoulders on which Roger Wolcott Sperry stood to receive his 1981 Nobel award. From 1936 to 1940, interrupted by the war and never resumed, Beritashvili and his talented fellow Nina Chichinadze performed a series of ingenious experiments, testing the ability of one cerebral hemisphere to search out memories initially laid down in the other. Although the puzzle posed by the “two brains” and the huge band of fibers connecting them, had been recognized for centuries, and desultorily explored, almost nothing was known concerning hemispheric interchange, if any. In their first two papers Beritashvili and Chichinadze (1936, 1937) showed that training the pigeon via one eye, to distinguish different colored patterns, conveyed no advantage to learning with the other, untrained eye; for these complex visual stimuli what had been learned with one hemisphere was inaccessible to the other. Chichinadze (1939) then showed that, with the same stimuli and procedure, switching eyes with cats or puppies did not disturb the memory for the discrimination; either the bilaterality of the optical input had allowed each hemisphere to learn simultaneously, or one hemisphere had behaviorally effective access to memories held in the other. The next paper (1940a) she showed, first, that even though colored patterns did not transfer, the general behavior of going to the feeder upon simple illumination did so. She then turned to the question of the interhemispheric commissure(s) supporting this simpler transfer. It is not clear whether the tectal commissures were tested, but the correct answer, as unanimously confirmed in postwar experiments of other researchers (e.g. Meier, 1971), turned out to be the supraoptic decussation. If this path is transected, there is no interhemispheric transfer even of the conditional reflex of going to the food box upon onset of light. In the last series of experiments Chichinadze (1940b) tested whether there was any evidence for subcortical participation in these responses to photic stimulation. The learned reactions were entirely absent via the eye contralateral to cortical extirpation.
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