A Spatiotemporal Examination Of The Mechanisms Involved In Long-Term Memory For Incrementally Acquired Information

Abstract

The existing literature examining the activity of plasticity-related molecular mechanisms suggests that early, post-learning activity of these mechanisms plays a role in later long-term memory (LTM) behavior. However, much of what we know comes from studies using one-trial learning paradigms. This dissertation has two main focuses. First, it examines the role of brain-derived neurotrophic factor (BDNF) in olfactory memories as a means of characterizing the effects of post-learning, molecular mechanisms on LTM for multi-trial learning. Second, it aims to provide a more comprehensive temporal profile for several plasticity-related proteins, across several brain regions for the same multi-trial learning event. In the first study, we showed that blockade of neurotrophin receptors in olfactory bulb (OB), including the BDNF receptor, TrkB, prevents LTM, but not short-term memory (STM) for a multi-trial learning task. In the second study, we found that acute blockade of the BDNF-TrkB pathway did not prevent the formation of specific, short-term odor representations, suggesting that the role of this pathway in the post-learning period is exclusively LTM consolidation. However, its exact role in the specificity of LTM representations remains to be explored. Finally, using high-throughput, quantitative RTPCR, we explored the timecourse of learning-induced transcription for several plasticity-related proteins across multiple brain regions. This study created a "spatiotemporal map" of the activity of several molecular mechanisms involved in LTM and lends temporal specificity to future studies of these mechanisms.