Neuronal plasticity and experience-dependent behaviors: Insights from fruit flies

An organism’s survival and success depends in large part on its ability to monitor changes in its environment and modify its behavior accordingly. For creatures with a nervous system, this involves transducing raw sensory information into electrical signals that are then processed internally, leading to a behavioral response. In order to adjust with the changes in the environment, neuronal populations can adjust their activity. This is known as neuronal plasticity and it leads to neuronal modulations at genetic, cellular and molecular level. At the genetic level, differential gene expression can alter synthesis of proteins associated with synaptic structures. Neuronal plasticity also includes changes in functional properties viz. ionic transport and electrical activity, known as functional plasticity. Structural modifications resulting in anatomical changes including circuit remodeling is also observed in some cases. However, neuronal plasticity is not restricted to higher brain functions or central nervous system, rather it also serves as a basic tool for adaptation at the levels of peripheral nervous system. The fruit fly, Drosophila melanogaster, provides a powerful genetic model to gain insight into the cellular and molecular basis of the development and function of nervous system. The nervous system of the fruit fly is simpler, allowing functional and genetic manipulations of individual genetically identifiable neurons. In this chapter, we review recent progress concerning neuronal plasticity in olfaction and gustation where olfactory and gustatory neuron’s responses alter with internal physiological state. Olfactory learning and memory also causes synaptic plasticity dependent on long term memory (LTM) formation, whereas gustatory system shows changes in response to different nutritional status as well as mating status.