chapter  4
12 Pages

Is There a Link between Visceral and Neurobehavioral Asymmetries in Development and Evolution?

Behavioral laterality on the basis of physiological neural asymmetries does not seem to develop under the control o f the same developmental mechanisms as asymmetries of the visceral organs. Earlier, we have found little evidence linking these two groups of asymmetries, which implies different developmental regulatory pathways and independent evo­ lutionary histories for visceral and telencephalic lateralizations.1 In this Chapter further argu­ ments are considered supporting independent developmental and evolutionary pathways for visceral and neurobehavioral asymmetries in vertebrates. Although the question remains con­ tradictory in view of some new evidence, this review implies, in particular, that the search for developmental mechanisms and genes controlling the establishment of brain lateralization (e.g., differential functioning of telencephalic hemispheres) can be based on approaches, which dif­ fer from attention only to human subjects and/or pathways leading to asymmetric morpholo­ gies in the diencephalon and major viscera. Recent advances in the studies o f asymmetries in invertebrates reveal deep roots for both neurobehavioral and visceral asymmetries dating the history of directional asymmetries back to the earliest bilateral organisms. This makes the un­ derstanding of developmental interactions between different asymmetry types complicated, but on the other hand, also makes possible diversification o f the experimental subjects and experimental approaches.