Acute Synaptic Activity Causes Differential miRNA Expression in The Drosophila melanogaster Larval Central Nervous System

The primary goal of this thesis was to determine if spaced synaptic stimulation induced the differential expression of microRNAs (miRNAs) in the Drosophila melanogaster central nervous system (CNS). Prior to attaining this goal, we needed to identify and validate a spaced stimulation paradigm that could induce the formation of new synaptic growth at a model synapse, the larval neuromuscular junction (NMJ). Both Channelrhodopsin- and high potassium-based stimulation paradigms adapted from (Ataman, et al. 2008) were tested. Once validation of these paradigms was complete, we sought to characterize the miRNA expression profile of the larval CNS by miRNA array. Following attainment of these data, we used quantitative real-time PCR (RT-qPCR) to determine if acute synaptic stimulation caused the differential expression of neuronal miRNAs. We found that upon high potassium spaced training in a wild type (Canton S) genotype, 5 miRNAs showed significant differential expression when normalized to a validated reference gene, the U1 snRNA. Moreover, absolute quantification of our RT-qPCR study implicated one miRNA: miR-958 as being significantly regulated by activity. Investigation into potential targets for miR-958 revealed it to be a potential regular of Dlar, a protein tyrosine phosphatase implicated in synapse development. This investigation provides the foundation to directly test our underlying hypothesis that, following spaced training, differential expression of miRNAs alters the translation of proteins required to induce and maintain these structural changes at the synapse.

The Relationships Between Child Maltreatment and Exploratory Behavior Implications for Development.

Findings from the fields of attachment theory, physiology, neurology, neurobiology and cognitive theory, when considered together, enhance understanding of the behavior and development of maltreated children. Each field describes from its own vantage how emotional trauma influences the quality and quantity of exploratory behavior. Development in many spheres is influemced by behavior. There is evidence from the field of neurobiology that experience ultimately influences the anatomy of the brain. Therefore, it can be hypothesized that constricted, overly defensive behavior in childhood ultimately compromises the development of the central nervous system itself. The altered neurobiology may help explain some of the developmental delays and failures seen in some maltreated children. Such developmental disruptions may include lowered intellectual performance, impaired ability to learn from experience, behavioral regressions under stress, and characterological abnormalities. This neurobiologic hypothesis has implications for research, intervention and training of professionals.It encourages 1) the identification of those deficit capacities most vulnerable to becoming neurologically based, 2) identification of ways to help the maltreated child explore and be accessible to developmental experiences, 3) more emphasis on the development of cognitive capacities, and 4) more breadth of training for professionals who work with maltreated children and their families.