Date of Completion

5-10-2020

Embargo Period

5-8-2020

Advisors

Eiling Yee, Emily Myers, Jon Sprouse, Roeland Hancock

Field of Study

Psychological Sciences

Degree

Master of Science

Open Access

Open Access

Abstract

If our conceptual knowledge about concrete objects is represented (in part) across the brain regions that are active when those objects are perceived, how is information from those regions integrated, or “bound” into a coherent whole? One potential mechanism for binding is synchronized neuronal firing. In particular, high-frequencies (e.g., gamma) may support local interactions, while lower frequencies (e.g., theta) may support longer-range interactions. Previous work has implicated the role of gamma and theta in binding, but not testing both on the same paradigm with a condition intended to create more cortical distance. We recorded participants’ EEG while they were presented with pairs of visual and auditory stimuli that were either congruent or incongruent (e.g., a picture of a lion followed by either a roar, or a bang sound, respectively), predicting that as observed in prior work (Schneider et al., 2008), integration and thus gamma power should be greater for congruent pairs. We also manipulated whether the sounds following the pictures were non-lexical (e.g., a roar sound) or lexical (e.g., the word “roar”), predicting that because interactions involved in integrating lexical information are presumably longer-range (i.e., not just interactions between visual and auditory processing brain areas, but between these regions and lexical processing areas as well) these interactions would produce more sustained theta activity. We found no differences between conditions in gamma. However, contrary to our predictions there was a significant increase in late theta for incongruent compared to congruent lexical trials, which we speculate may be due to working memory load. Our findings underscore the need for work examining the relationship between synchronous neural firing and integration during conceptual processing, as better understanding may lead to improvements in interventions for clinical populations, as well as better models of semantic memory organization and learning.

Major Advisor

Eiling Yee

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