Dynamics of alpha power in multimodal processing

Alpha oscillations are one of the most, if not the most, prominent signals obtained from human electroencephalography (EEG). In fact, they were the first rhythmic pattern observed using EEG nearly 100 years ago and scientists have been uncovering whether and how they relate to brain and cognitive function ever since. Typically characterized as an ongoing ~10 Hz rhythm, most prominent over posterior scalp locations, alpha has repeatedly shown to be related to the visual modality, aiding sensory, perceptual, and cognitive processes. Particularly in the case of visual selective attention, alpha has been considered a mechanism which both selects newly formed visual representations and protects existing representations from interference through alpha suppression and alpha maintenance, respectively. However, there is growing evidence that alpha may also serve multimodal processes, in addition to visual ones, and this dissertation provides evidence for this assertion. In Chapter 1, I provide a brief history of the research on the alpha rhythm and overview its engagement in visual, cross-modal, and auditory processing to motivate the investigation of alpha in multimodal contexts in subsequent chapters. In Chapters 2 and 3, I present a coordinated pair of studies which investigated the role of alpha in multimodal competition using an auditory task with the eyes open and closed, respectively enabling and disabling visual inputs in parallel with the incoming auditory stream. Results indicated that eye status and level of attentional engagement modulate alpha, which suggests that alpha may be involved in processing multimodal percepts and/or may emanate at least in part from multimodal cortical regions. In Chapter 4, alpha’s role in multimodal processing was investigated further by assessing alpha dynamics during bimodal selective attention, in which attention is allocated to either the visual or auditory stream while the eyes were open. Here, we found alpha engagement specific to visual attention processing is occipitally maximal and sustained over time, whereas general alpha engagement used in both visual and auditory attention processing is parietally maximal and occurs transiently. Finally, Chapter 5 summarizes the results of the previous chapters and proposes several avenues for future endeavor. Overall, this work should encourage alpha researchers to widen the lens through which they view alpha oscillations to include the possibility that this preeminent brain rhythm may be a generalized mechanism used throughout the cortex to process information from multiple sensory streams.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Psychology

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2022

Author dc:creator

• Clements, Grace Morgan

Contributors dc:contributor

• Fabiani, Monica
• Gratton, Gabriele
• Beck, Diane M
• Sadaghiani, Sepideh
• Keil, Andreas

• EEG alpha power
• EEG theta power
• Alpha suppression
• Alpha enhancement
• Multimodal processing
• Resource competition
• Selective attention
• Preparatory period

Statement dc:rights

• Copyright 2022, Grace Clements

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/115544

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F115544