Precise models of cortical synaptic plasticity are essential for understanding how information is stored in the brain and how functional neural connection patterns get established. Understanding cortical plasticity requires coordinated investigation of both underlying cellular mechanisms and their systems-level consequences in the same model system. However, establishing connections between the cellular and system levels of description is non-trivial. A major contribution of theoretical neuroscience is that it can link different levels of description, and in doing so can direct experiments to the questions of greatest relevance.
The objective of the current project is to generate a theoretical description of experience-dependent plasticity in the rodent visual system. The advantages of rodents are, first, that knowledge of the molecular mechanisms of synaptic plasticity is relatively mature and continues to be advanced with genetic and pharmacological experiments, and second, rodents show robust receptive field plasticity in visual cortex that can be easily and inexpensively monitored with chronic recording methods.
In this project, models of synaptic plasticity are based on realistic assumptions about the activity of inputs to visual cortex from the lateral geniculate nucleus (LGN). These assumptions are based, when possible, on actually recordings of LGN activity in rodents, in different viewing conditions that induce receptive field (RF) plasticity. These data will be integrated into formal models of synaptic plasticity. In this proposal the dynamics of RF plasticity will be simulated using existing spike rate-based algorithms and compared with experimental observations. Additionally, the consequences of new biophysically-plausible plasticity algorithms will be analyzed and compared with experiments. Two simulation packages, Plasticity and P-spike, will be developed as part of the project and made available on the web to other researchers.
By improving our understanding of the basis for learning, memory and developmental plasticity, these investigations will suggest new strategies for treating learning disabilities and neurodevelopmental disorders in children, as well as learning and memory problems in the aging population.
