Date of Degree

10-2014

Document Type

Dissertation

Degree Name

Ph.D.

Program

Psychology

Advisor(s)

John J. Foxe

Sophie Molholm

Subject Categories

Neuroscience and Neurobiology | Social and Behavioral Sciences

Keywords

attention, development, electroencephalography, ERP, spatial, vision

Abstract

Top-down attention is the focusing of attention at one's will through knowledge regarding a current task. There is evidence that top-down attention involves the modulation of sensory cortices by higher order regions. However, the mechanisms of top-down attention across sensory modalities, its influence on early sensory inputs, as well as interactions with motivational systems remain unclear. We performed the following set of electrophysiological experiments in typically developed adults and adolescents to examine these areas. 1) The supramodal attentional theory holds that parietally-based attentional mechanisms are shared across sensory modalities. We tested the supramodal theory by examining if lateralized parieto-occipital alpha-band activity, an established metric of top-down spatial attention, was observed in an audiospatial and visuospatial task. In support of the supramodal theory, we observed similar anticipatory alpha-band processes across auditory and visual tasks, but we also found an interaction of supramodal and sensory-specific attentional control processes. 2) There is evidence that top-down attention influences information immediately upon its arrival to sensory cortices, although there is debate in this area. In the current work, volitionally-driven top-down attention was engaged toward one of several overlapping surfaces in an illusion, in which the perceived brightness of the attended surface was enhanced. We observed the attentional enhancement of early visual evoked potentials, indicating that top-down attention shapes the earliest activations in visual cortices. 3) It is well known that motivation impacts attention, but the neural bases of these interactions remain unclear. We examined how level of interest in stimuli influenced top-down spatial attention mechanisms in typically-developing adolescents. Motivation enhanced established attentional processes during the anticipation of high vs. low interest stimuli, but also independently influenced frontal and parieto-occipital activations. These findings provide potential implications to inform clinical measures to improve impaired attentional processes in clinical populations (e.g. individuals with autism spectrum disorders). In sum, these studies revealed the powerful influence of top-down attentional control and its interacting systems on neural activations through several stages of anticipatory and post-stimulus processing during development and adulthood.

 
 

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