Sensory experience drives long-lasting changes in neural circuit function, which are essential for brain development and learning. A dominant model is that such plasticity involves long-term potentiation (LTP) and depression (LTD), well-studied mechanisms that increase or decrease the strength of synaptic connections between neurons. LTP and LTD are triggered by specific local neural activity patterns according to quantitative synaptic learning rules. Despite an increasing molecular understanding of plasticity, the relevant learning rules driving LTP and LTD in vivo are not known. Work in this proposal will identify these learning rules, in order to allow a quantitative description of how plasticity is induced and how information is stored in neural circuits. The model system is the whisker region of rat somatosensory cortex (S1), which is a classical system for studying the effects of experience on brain function. Whisker deprivation drives LTD at specific S1 synapses. A prospective, model-independent approach will be taken to identify the specific neural activity patterns and learning rules that drive LTD in vivo. The strategy is to record S1 spike trains in awake, behaving rats, and to use quantitative analysis techniques to identify spike train parameters that are altered acutely by deprivation, and that constitute candidate activity patterns that may drive LTD in vivo. These candidate parameters will be played back to neurons in S1 slices in vitro to determine which parameters actually drive LTD, and to characterize the learning rules governing such plasticity. This approach will identify novel learning rules driving plasticity in vivo, and will confirm or reject involvement of previously known rules. Identification of the relevant learning rules for plasticity will provide a critical bridge between existing molecular/synaptic and systems/theoretical descriptions of plasticity and learning. By advancing our understanding of cortical plasticity, this work will suggest new strategies for treating learning disabilities and memory disorders during aging. This work will also support improved instructional techniques in undergraduate education by developing a small-group, discussion-format course to promote critical thinking and reasoning in biology and neuroscience. This course will emphasize structured discussions, critical interactive thinking exercises, and physical demonstrations to teach scientific reasoning skills and promote improved knowledge retention, and will provide an alternative to standard, large-lecture format classes. As part of this effort, graduate students will be intensively trained in interactive, small-group teaching techniques, which will aid their professional development as future educators.
