Lateralization of neural control for vocalization by the frog (Rana pipiens)

The hypothesis that anuran vocalization is lateralized was examined. Vocalization was induced by clasping the animal behind the forelimbs for 30 sec in the morning and 30 sec in the afternoon for 6 weeks. On the basis of the number of baseline vocalizations, four matched groups were formed ( n = 11): nonoperates, sham operates, and animals receiving knife cuts in the left or right side just posterior to the brain areas that are thought to be the major vocalization generators. Following recovery, the number of vocalizations was recorded for 6 additional weeks. Vocalization was reduced significantly more by sections in the left side than in the right side, suggesting that one of the most basic relationships between the brain and vocal communication evolved very early and that natural language is based on previous adaptations in animals.