In this laboratory, the fMRI method has been used to address the network of cortical areas participating in clinical measures of executive function. A data analysis procedure that averages activation across functionally relevant anatomical regions (e.g., dorsolateral frontal, medial frontal, posterior tertiary cortex, etc.) has been developed. This procedure allows ANOVA factorial designs using grouping variables such as cortical region, laterality, experimental vs. control task, and gender to determine amount of brain activation associated with the various main effects and interactions. Such studies have been useful to address clinically meaningful questions about the structural and functional basis of tests used by the typical neuropsychologist. Not only do these type of studies answer questions about the sensitivity and specificity of tests to various brain regions, but also questions about individual variability associated with cognitive style, gender, and other variables of interest as they bear upon test performance can be addressed.
A recent study of spatial working memory (Osmon, Zigun, Suchy, & O'Reilly, in submission) found differences in frontal, occipital, and parietal activation associated with gender. These differences suggested that men, typically better at spatial tasks, had more frontal relative to occipital activation while women had the opposite relationship. Such results show the importance of factorial designs in addressing significant individual differences in performance on clinical tests.
Such individual variability can be observed in the pictures of regional activation associated with a Stroop task below. While general commonalities in regional activation can be gleened across participants (e.g., dorsolateral and medial frontal lobe, inferior parietal lobule, occipital cortex), much variability between participants is also apparent. The pictures below represent activation for six different participants.
