- Friday, January 8th 2021 at 16:00 - 17:00 UK (Other timezones)
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A hallmark characteristic of Alzheimer’s disease is difficulty in retrieving semantic memories, or memories that encode facts and concepts. However the cognitive mechanisms that explain these impairments have been debated. Central to this debate is whether the impairments are due to degradation of an individual’s semantic representation or failures in executive retrieval processes. Recent work has shown that semantic fluency data (e.g., listing animals) can be modeled as a censored random walk over a semantic network. In this talk, I show how this model can be inverted to estimate semantic network representations for individuals. Using a longitudinal corpus of fluency data, I estimate a semantic network for individuals with Alzheimer’s disease and healthy controls, and compare these networks between groups. I find that semantic impairments in Alzheimer’s disease can be explained by a combination of both representational degradation and retrieval process failures. As the semantic fluency task is widely used as a clinical diagnostic test, this approach may be amenable to the study of other cognitive disorders.
Jeff Zemla
Assistant Professor
Department of Psychology
Syracuse University