Dissertations, Theses, and Capstone Projects

Date of Degree

9-2019

Document Type

Dissertation

Degree Name

Ph.D.

Program

Psychology

Advisor

Tatiana A. Emmanouil

Committee Members

Timothy M. Ellmore

Jonathan B. Levitt

Jennifer A. Mangels

Tony Ro

Subject Categories

Cognition and Perception | Cognitive Neuroscience | Cognitive Psychology

Keywords

neural oscillations, EEG, attention, perception, psychophysics, saccades

Abstract

Visual sensitivity fluctuates rhythmically, in-synch with ongoing, EEG-recorded neural oscillations across a wide range of frequencies (~1-25hz). Some recent work has suggested that these perception-related neural oscillations can be entrained by rhythmic visual stimulation. Evidence is also emerging that the entrainment of ongoing oscillations in visual and auditory cortices is involved in rhythmic temporal expectations. In the introduction chapter, I attempt to bridge these bodies of literature and hypothesize that rhythmic visual stimuli automatically entrain ongoing, perception-related neural oscillations and that this mechanism supports the maintenance of rhythmic temporal expectations. Chapters 2 and 3 address this hypothesis from different angles. In Chapter 2, we explored the role of the entrainment of ongoing delta (~1.5hz) oscillations in a novel rhythmic temporal expectation task involving spatial attention. Demonstrating the existence and functional relevance of visual entrainment, we found widespread synchronization to an attended, lateralized, rhythmic stimulus which was modulated by task performance. In Chapter 3, we tackled a different topic which has been the focus of recent debate: whether the entrainment of alpha (8-13hz) oscillations is a unique type of entrainment. Building on previous work, we tested behaviorally and electrophysiologically whether an individual’s peak alpha frequency can be shifted by rhythmic visual stimulation. Despite finding evidence for alpha entrainment, we found no indication that this involved individual alpha frequency (IAF). Our findings suggest that previous work should be reconsidered within the hypothesized framework I have presented: that visual entrainment is not a frequency-specific phenomenon. Chapter 4 explores a different topic because it was conducted with my first PhD advisor. We tested the effects of slow and fast saccade pacing on baseline saccade metrics and whether saccade pacing influences a phenomenon known as saccadic adaptation. Saccadic adaptation is a calibration mechanism that ensures eye movements are accurate despite structural and functional changes that occur during development and due to injury. One notable finding was that faster-paced saccades resulted in greater saccadic adaptation. The faster-paced saccade condition was also more rhythmic, suggesting that rhythmic temporal expectations could have influenced this basic oculomotor calibration process. In the concluding chapter, I integrate our findings with existing literature to argue that visual entrainment creates rhythmic temporal expectations which are automatic, independent of stimulus modality, and mechanistically different from other types of temporal expectation.

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