9423616 The Neurotransmitter dopamine has been strongly implicated in the physiological regulation of "simple" behaviors, such as motor control, as well as in higher order cognitive function. This work addresses the functional consequences of perturbing the normally exquisitely regulated levels of dopamine in the nervous system by manipulation of the regulatory mechanisms directing dopamine synthesis. The choice of Drosophila melanogaster as the model system facilitates the use of molecular genetic techniques to circumvent limitations encountered in other systems. These studies take advantage of recombinant DNA methodology to (1) modulate the expression of tyrosine hydroxylase, the rate-limiting biosynthetic enzyme in the synthesis of dopamine, and (2) determine the functional consequences of perturbing these mechanisms in the intact animal.