Neuroanatomic overlap of working memory and spatial attention networks: A functional MRI comparison within subjects

Frontal and posterior parietal activations have been reported in numerous s tudies of working memory and visuospatial attention. To directly compare th e brain regions engaged by these two cognitive functions, the same set of s ubjects consecutively participated in tasks of working memory and spatial a ttention while undergoing functional MRI (fMRI). The working memory task re quired the subject to maintain an on-line representation of foveally displa yed letters against a background of distracters. The spatial attention task required the subject to shift visual attention covertly in response to a c entrally presented directional cue. The spatial attention task had no worki ng memory requirement, and the working memory task had no covert spatial at tention requirement. subjects' ability to maintain central fixation was con firmed outside the MRI scanner using infrared oculography. According to cog nitive conjunction analysis, the set of activations common to both tasks in cluded the intraparietal sulcus, ventral precentral sulcus, supplementary m otor area, frontal eye fields, thalamus, cerebellum, left temporal neocorte x, and right insula. Double-subtraction analyses yielded additional activat ions attributable to verbal working memory in premotor cortex, left inferio r prefrontal cortex, right inferior parietal lobule, precuneus, and right c erebellum. Additional activations attributable to covert spatial attention included the occipitotemporal junction and extrastriate cortex. The use of two different tasks in the same set of subjects allowed us to provide an un equivocal demonstration that the neural networks subserving spatial attenti on and working memory intersect at several frontoparietal sites. These find ings support the view that major cognitive domains are represented by parti ally overlapping large-scale neural networks. The presence of this overlap also suggests that spatial attention and working memory share common cognit ive features related to the dynamic shifting of attentional resources. (C) 1999 Academic Press.