ABSTRACT Our overall goal is to elucidate the different mechanisms available to a neuron to control mitochondria at a subcellular level, and the genetic bases of these capabilities. Mitochondria accumulate within nerve terminals where they generate most of the ATP required to package and recycle neurotransmitters and to maintain transmembrane ion-balances. Neural function is reliant on mitochondrial function to sustain neurotransmitter release, and mitochondrial dysfunction is a hallmark of many neurodegenerative diseases. It is therefore imperative to gain a better understanding of the mechanisms that neurons use to control mitochondria at the sub-cellular level of nerve terminals, and how this might differ between neuron types. Here we present the hypothesis that sites at which mitochondria interact with the plasma membrane (PM) represent a form of mitochondrial utilization that confers advantages in those parts of a neuron with high power demands, such as nerve terminals. We propose to elucidate the functional significance of such interactions, and their genetic underpinnings. To do this we are adopting a structure-function approach, exploiting the small size and genetic tools of Drosophila. In Aim 1 we will use serial block face scanning electron microscopy to determine the neuron types, and subcellular regions served by mitochondrial-PM interactions. In Aim 2 we will use a novel form of super-resolution to investigate the formation and disassembly of these interactions, and the functional consequences for presynaptic physiology and neurotransmission. In Aim 3 we will investigate the role of a select group of genes identified as candidates for a role in mitochondrial-PM interactions. The significance of this proposal lies in its potential to uncover novel neuronal and sub-cellular specific mitochondrial functions, and the genetic bases of these functions, which may throw light on the selective neuronal vulnerability observed in different neurodegenerative diseases and neurological conditions.