RESEARCH ARTICLE
The Timecourse of Activation Within the Cortical Network Associated with Visual Imagery
Sharlene D Newman*, Donghoon Lee, L Christopher Bates
Article Information
Identifiers and Pagination:
Year: 2007Volume: 1
First Page: 1
Last Page: 9
Publisher ID: TONIJ-1-1
DOI: 10.2174/1874440000701010001
PMID: 19018309
PMCID: PMC2577936
Article History:
Received Date: 4/7/2007Revision Received Date: 20/7/2007
Acceptance Date: 24/8/2007
Electronic publication date: 20/9/2007
Collection year: 2007

Abstract
The current study examined the hemodynamic timecourse of activation within a network of regions that is thought to be associated with visual imagery. Two experimental conditions were examined that were designed to place differential demands on specific nodes within the visual imagery network. The two tasks were an object inspection task and a mental rotation task. The two conditions recruited overlapping cortical regions; however several regions revealed a differential response to object inspection and mental rotation. The mental rotation condition elicited greater activation in parietal cortex, lateral occipital/temporal regions, and bilateral prefrontal cortex. Conversely, the object inspection condition elicited greater activation in inferior extrastriate cortex, the inferior frontal gyrus, and the right cerebellum. When examining the timecourse of activation three different timecourse patterns were observed across cortical regions and conditions. The shape of the hemodynamic timecourse appears to correspond strongly with the cognitive processing taking place within the region, not the stimulus paradigm. The paper discusses the significance of those varying timecourse shapes and has implications for the appropriateness of using the canonical hrf during fMRI data analysis.