Computational Neuroscience Initiative111 Levin Building 425 S. University Avenue
Sarah Solomon
Schapiro Lab
University of Pennsylvania
Semantic Plasticity in Neural Systems
Our representations need to be stable enough to support our general knowledge but flexible enough to incorporate new information as our environment changes. How does the human brain manage this stability-plasticity trade-off, and how does our semantic memory system in particular support this kind of flexibility? I will describe some areas of research that relate to these questions, and then present a recent project that tackles this question head on. We analyzed a large fMRI dataset (Natural Scenes Dataset) in which participants viewed thousands of natural images across a period of many months. We found that, within the medial temporal lobe (MTL), semantic item representations gradually drifted over time (~8 months). However, rapid plasticity was observed only in parahippocampal cortex, such that item co-occurrence statistics warped item representations within a single session. In conjunction with whole-brain analyses, these results suggest that the brain solves the stability-plasticity trade-off by promoting plasticity in only a subset of semantic regions.
A pizza lunch willl be served.