Barry J. Dickson,
Institute of Molecular Pathology, Vienna, Austria
Innate behaviours are specified by genes, which act by directing the assembly and function of the relevant neural circuits. Classical forward genetic studies in C. elegans and Drosophila, and more recently in the mouse, have begun to identify some of the genes that influence innate behaviours in these species. A major limitation to such approaches is the pleiotropy of gene function: most genes have multiple functions in diverse aspects of an animal's development, physiology and behaviour, making it exceedingly difficult to tease out specific functions in specific behaviours.
Even where this has been possible, it has often been difficult to determine how such a "behaviour gene" influences the assembly or function of the appropriate neural circuits.
In Drosophila, the problem of pleiotropy can now largely be overcome by using transgenic RNAi to disrupt gene function specifically in defined neuronal populations, allowing systematic and efficient screens for genes that modulate innate behaviours. Tools are also now available to define the site-of-action of such genes, so that the relevant neural circuits can be identified, often with single cell resolution.
Finally, optical and electrical recording can be used to explore information flow within these defined neural circuits, in both wild-type and genetically manipulated animals. Together, these methods open up exciting new possibilities to systematically identify genes that influence behaviour, and to understand how they do so. I will illustrate how some of these approaches can be applied to the study of sex-specific innate behaviours in Drosophila. |
