This is an individual National Research Service Award for post-doctoral research training, which provides support for promising Fellowship Applicants with the potential to become productive, independent investigators in scientific health-related research fields. Synaptic plasticity is believed to underlie learning and memory, the basis for behavior. Neuroligins are synaptic proteins, and mutations in the genes coding for these proteins and their binding partners have been found in autism spectrum disorders. These disorders are characterized by impaired social interactions, and several mice that either lack the neuroligin 1 gene or have a specific mutation added that is found in autistic patients are known to have impaired social behavior. Recent studies have found mutations in many activity-dependent genes in autistic patients, and it is possible that the neuroligins are important in activity-dependent synaptic plasticity. The objective of this study is to investigate the role of neuroligins in synaptic plasticity at excitatory and inhibitory synapses in order to better understand the role of neuroligins in physiology and pathophysiology.