Pulsed out of awareness: EEG alpha oscillations represent a pulsed inhibition of ongoing cortical processing

Alpha oscillations are ubiquitous in the brain, but their role in cortical processing remains a matter of debate. Recently, evidence has begun to accumulate in support of a role for Alpha oscillations in attention selection and control. In this thesis, a series of studies is presented investigating the role of Alpha oscillations in visual processing, learning, and awareness. I propose that Alpha oscillations represent a general pulsed inhibition in the brain. Chapter 1 contains a review of evidence that 8-12 Hz oscillations in the brain have a general inhibitory role in cognitive processing, with an emphasis on their role in visual processing. Chapter 2 presents additional evidence for this general inhibitory role, in a study where EEG Alpha is used to predict the rate of improvement in a complex video game training program. Chapter 3 summarizes research supporting the proposal that Alpha represents a pulsed inhibition of ongoing neural activity. The phase of the ongoing EEG can influence evoked activity and subsequent processing. It is proposed that Alpha exerts its inhibitory role through alternating microstates of inhibition and excitation. Chapter 4 and Chapter 5 discuss evidence that this pulsed inhibition can be entrained to rhythmic stimuli in the environment, such that preferential processing occurs for stimuli at predictable moments, leading to oscillations in visual awareness. The entrainment of a preferential phase of ongoing Alpha oscillations may provide a mechanism for temporal attention in the brain. Chapter 6 reports the results of an experiment combining fast optical imaging using the event-related optical signal (EROS) with EEG recording in a meta-contrast masking task. This multimodal combination is used to investigate the network of brain areas oscillating at Alpha frequencies and their influence on visual awareness, as well as the frontal and parietal areas modulating this oscillatory activity. Chapter 7 concludes that together, this series of studies provides the foundation for an account of Alpha oscillations as a general pulsed inhibition mechanism which can be entrained by external stimulation and modulated by top down influences from the fronto-parietal attention network. Given the rhythmic nature of this proposed inhibitory mechanism, this pulsed inhibitory account of Alpha has important implications for many common cognitive phenomena, such as the attentional blink, and seems to indicate that our visual experience may at least some times be coming through in waves. Chapter 1 contains a review of evidence that 8-12 Hz oscillations in the brain have a general inhibitory role in cognitive processing, with an emphasis on their role in visual processing. Chapter 2 presents additional evidence for this general inhibitory role, in a study where EEG Alpha is used to predict the rate of improvement in a complex video game training program. Chapter 3 summarizes research supporting the proposal that Alpha represents a pulsed inhibition of ongoing neural activity. The phase of the ongoing EEG can influence evoked activity and subsequent processing, and it is proposed that Alpha exerts its inhibitory role through alternating microstates of inhibition and excitation. Chapter 4 and Chapter 5 discuss evidence that this pulsed inhibition can be entrained to rhythmic stimuli in the environment, such that preferential processing occurs for stimuli at predictable moments, leading to oscillations in visual awareness. The entrainment of preferential phase of ongoing Alpha oscillations may provide a mechanism for temporal attention in the brain. Chapter 6 reports the results of an experiment combining fast optical imaging using the event-related optical signal (EROS) with EEG recording in a meta-contrast masking task. This multimodal combination is used to investigate the network of brain areas oscillating at Alpha frequencies and their influence on visual awareness, as well as the frontal and parietal areas modulating this oscillatory activity. Chapter 7 concludes that together, this series of studies provides the foundation for an account of Alpha oscillations as a general pulsed inhibition mechanism which can be entrained by external stimulation and modulated by top down influences from the fronto-parietal attention network. Given the rhythmic nature of this proposed inhibitory mechanism, this pulsed inhibitory account of Alpha has important implications for many common cognitive phenomena, such as the attentional blink, and seems to indicate that our visual experience may at least some times be coming through in waves.

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

2011

Author dc:creator

• Mathewson, Kyle E.

Contributors dc:contributor

• Gratton, Gabriele
• Fabiani, Monica
• Beck, Diane M.
• Lleras, Alejandro
• Simons, Daniel J.

• Alpha
• Pulsed Inhibition
• Electroencephalography (EEG)
• Oscillations
• Awareness
• Masking

Statement dc:rights

• Copyright 2011 Kyle E. Mathewson

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/26295

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/26295