Lateralized visual and motor responses in the green tree frog, 'Litoria caerulea'

Abstract

There is increasing evidence of brain lateralization in frogs and toads, based on studies of their responses to various types of visual stimuli and also from their limb preferences. In a range of toad species, agonistic and predatory responses are preferentially directed by the left and right eyes, respectively. We investigated visual lateralization in the adult Australian green tree frog, a species with marked differences in ecological habitat and evolutionary history compared to the bufonids (toads). We also investigated forelimb preferences in a climbing task, using the same group of frogs. Strong and significant left-eye preferences were found for directing agonistic responses at other frogs, contrasting with a nonsignificant trend towards right-eye preferences for predatory responses. Furthermore, the right forelimb was used preferentially as the leading limb to control climbing to an upright position after the frog had been inverted in the vertical plane. In each instance, the laterality of behaviour corresponded with the lateralization of comparable behaviours in higher vertebrates, supporting the hypothesis that brain lateralization is conserved from a common lateralized ancestor.