Complementary right and left hemifield use for predatory and agonistic behaviour in toads

Abstract

Cerebral lateralization, the differing specializations of the right and left sides of the brain once thought to be unique of humans, is now well known to occur in both birds and mammals. Here we report that in toads the right hemisfield of vision guides predatory tongue-striking responses towards moving prey and the left hemisfield guides agnostic tongue-striking responses towards conspecifics. This indicates, for the first time, complementary cerebral specializations for visual processing in anurans, and strongly supports the hypothesis that lateralized brain functions in birds and mammals may have arisen from a common lateralized ancestor. Complementary specializations in visual processing may have originally evolved to avoid problem of response competition during control of medial organs such as the tongue in organisms with laterally placed eyes and, in organisms with wider binocular overlap, it appears to be retained for initial detection of stimuli in the extreme lateral fields.

The costs of hemispheric specialization in a fish

“…For example, toads, chicks and dunnarts differ in their promptness to react to a predator depending on the visual hemifield in which it appears (Lippolis et al 2002(Lippolis et al , 2005Dharmaretnam & Rogers 2005), and mosquitofish make closer cooperative predator inspection when predator and shoalmates are seen with the correspondingly preferred eye (De Santi et al 2001). Gelada baboons and Anolis lizards are more likely to attack a conspecific on one side than the other (Deckel 1995;Casperd & Dunbar 1996), and side biases are shown by toads, chicks and pigeons in food detection (Vallortigara et al 1998;Diekamp et al 2005). Investigating whether individuals with greater left -right differences pay larger costs even in these cases will help us to assess the generality of our findings and expand our understanding of the selective mechanisms maintaining individual differences in lateralization.…”

“…Toads, for example, are more likely to strike at a prey moving in their right lateral field of vision while agonistic responses are delivered preferentially to a conspecific seen on their left side (Vallortigara et al 1998). Similar differences have been found in birds and reptiles (Deckel 1995;Dharmaretnam & Rogers 2005).…”

The parapineal mediates left-right asymmetry in the zebrafish diencephalon

“…Examples include the left hemisphere specialization of rodents in the production and perception of vocalizations (Ehret, 1987;LeMay, 1999), and the preferential eye use in food-searching behavior and predator recognition exhibited by amphibians, fish and birds (Deng and Rogers, 1997;Miklosi et al, 2001;Miklosi et al, 1998;Rogers, 2000;Vallortigara et al, 1998). The wide phylogenetic distribution of asymmetric behaviors suggests that functional lateralization of the brain is not a novel feature of the human cerebral cortex, but arose early in vertebrate evolution.…”

Prior exposure to a predator influences lateralization of cooperative predator inspection in the guppy,Poecilia reticulata

“…Demonstration of animal lateralization also derives in great part from selective lesions, pharmacological inactivation of one hemisphere or from temporary occlusion of one eye, ear, or nostril (see Bradshaw & Rogers, 1993, for a review). Behavioural asymmetries in the use of the eyes are known to be the manifestation of underlying brain functional specializations and have been demonstrated to occur in all vertebrate classes (fish: Cantalupo et al, 1995;Miklosi et al, 1998;amphibians: Robins et al, 1998;Vallortigara et al, 1998;reptiles: Deckel, 1995;birds: Andrew, 1988;Vallortigara et al, 1999a;mammals: Casperd & Dunbar, 1996). These studies, however, may not indicate to what extent laterality is a normal feature of an animal's behaviour.…”