Local mRNA translation is critical for axon regeneration, synapse formation, and synaptic plasticity. While much of research has focused on local translation in dendrites and in peripheral axons, less is known about local translation in smaller diameter central axons due to the technical difficulty of accessing them. We developed microfluidic technology to allow access to axons, as well as nascent boutons and fully functional boutons. We identified multiple transcripts that are targeted to cortical and hippocampal axons in rat (Taylor et al. J Neurosci 2009). Importantly, this work countered the prevailing view that local mRNA translation does not occur in mature axons. We are actively investigating transcripts in axons that may play a role in establishing proper synaptic connections. We are also using our technology to identify transcripts targeted to axons and boutons in human neurons. These studies are a critical step towards the identification of key genes and signaling molecules during synapse development, axonal regeneration, and proper circuit function.