Abstract
Behavioral and fMRI techniques have been utilized to investigate the neuroanatomical correlates of goal directed visual attention. It was hypothesized that comparing target to non-target activation for each participant (Single subject event-related functional magnetic resonance imaging [ER-fMRI], on two visual 1-back working memory tasks, with three levels of difficulty, would reveal a network of frontal and parietal sites, similar to Corbetta's visual attention networks with a significant positive correlation between the accuracy level for each task and the strength of the signal contrast between target and non-target activation. One task used highly familiar cartoon faces of varying colour and emotional expression, expected to primarily activate the left hemisphere, while the second task was expected to activate the right hemisphere, using 3-D cubes with 0, 45 or 90 deg rotations. The 1-back design required manipulation, continuous updating and selective attention, with each task type requiring different button presses to differentiate repeat and non-repeat responses. The block designed and ER-FMRI results both demonstrated fronto-parietal networks of activation predominately in the left hemisphere for both tasks differing with respect to stimulus class and across individuals. No correlation was observed between the strength of activation and task accuracy. Increasing difficulty of the mental rotation 1-back task appeared to activate a bilateral network of areas with greater bilateral parietal than frontal activation, while the facial attributes tasks activated largely LH dominant frontal areas.