Exploring the switching of the focus of attention within working memory: A combined event-related potential and behavioral study

Task switching involves working memory: Evidence from neural representation

It is generally assumed that task switching involves working memory, yet some behavioral studies question the relationship between working memory and task switching ability. This debate can be resolved by directly comparing the brain activity pattern in task switching and working memory processes. If the task switching involves working memory, the neural activity patterns evoked by such two tasks would exhibit higher similarity. Here, we employed the task switching task and working memory to investigate the characteristic of the neural representation in such two cognitive processes. A conjunction analysis showed that the bilateral superior parietal lobule (SPL), bilateral insula, bilateral middle frontal gyrus (MFG), bilateral dorsal lateral prefrontal cortex (DLPFC) and pre-supplementary motor area (pre-SMA) were commonly and significantly activated in both task switching and working memory task. Critically, we found that task switching and working memory processing elicited similar activity patterns in bilateral SPL, right insula, left MFG, left DLPFC and pre-SMA, consistent with common neural processes for both tasks. These results not only suggest that the task switching process involves working memory from the perspective of neural representation, but also provide major new insights into the neurocognitive links between task switching and working memory.

Electrophysiological correlates of the effect of set size on object switching in working memory

Previous studies have revealed the effect of set size (the number of activated items) on object switching in working memory, but the underlying neural mechanism remains unclear. In this study, participants were asked to first remember two (small size) or three (large size) two-digit numbers and the corresponding geometrical figures as different references for numerical comparison and then compare a series of numbers (10-99) to the reference numbers cued by different geometrical figures. The cue repeated or switched across trials. Behavioral results revealed that the switch cost was greater in the large-size condition than in the small-size condition. Event-related potential results showed that in the N2 component, an interaction was observed between set size and transition, with a significant transition effect (switch minus repeat) in the large-size condition and a non-significant transition effect in the small-size condition. The same interaction was observed in the P3 component, with a larger amplitude difference (switch minus repeat) in the large-size condition than in the small-size condition. These results suggested that when set size is increased, the effort to inhibit the irrelevant items increases, resulting in large cost of object switching in working memory.