The tripartite model of memory proposed the requirement of attentional switching when accessing different items in working memory [J. Exp. Psychol. Learn. Mem. Cogn. 27 (2001) 817]. This internal focus of attention is limited to just one item and the switching process is time-consuming [Mem. Cogn. 26 (1998) 263]. In the current study, given a three-digit list stored in working memory, we found that it took longer to shift attention in the direction of "Upstream" than "Downstream", and that each shift was a "single step" process. To investigate the neural basis of this type of attention switching, we performed a functional MRI study. The results revealed that at least three important brain areas are involved, including the left dorsal lateral prefrontal cortex, the cingulate gyrus, and the medial occipital cortex. These areas all showed greater activation in the attention shift condition compared to control conditions of no (or decreased) attention shift requirements. In addition, the hemodynamic activities in these areas are highly correlated, suggesting a strong functional connectivity between them. Taken together with evidence from several recent investigations, our results suggest that these areas each play an important and specific role in collaboratively supporting the function of attention shift in working memory.
Bibliographical noteFunding Information:
We thank Patty Costello for her comments on an earlier version of this paper and Stephen LaConte for improving the quality of the writing. This research is supported by the National Nature Science Foundation of China (39928005, 39970253), National Basic Research Program of China (G1998030509), Outstanding Oversees Chinese Scholars Fund of CAS, NIH (RO1MH55346, R01EB00321), Georgia Research Alliance, Whitaker Foundation, and James S McDonnell Foundation.
- Attention shift
- Functional MRI
- Working memory