Reorienting Spatial Attention within Visual Working Memory

Attention and working memory (WM) are intertwined core cognitive processes. Through four experiments with 133 participants, we dissociated the impact of two types of covert spatial attention, endogenous vs. exogenous, on visual WM. Behavioral results consistently indicated that exogenous attentional cues were more advantageous than endogenous ones in enhancing the precision of visual WM under load-2, while they equalized under load-4. In addition, physiological and neural data explained the mechanisms. Converging evidence from eye-tracking, electroencephalography, and magnetoencephalography suggested that fast attentional processing induced by exogenous cues lead to early top-down information from the dorsal lateral prefrontal cortex (DLPFC) to sensory cortices. The differential frontal activities were further correlated with the behavioral distinctions between exogenous and endogenous cues, and transcranial magnetic stimulation over DLPFC at the same time period abolished the exogenous advantage. Taken together, traditionally considered bottom-up attentional processing induced by exogenous cues rapidly engages top-down signals from the frontal cortex, which leads to stronger behavioral benefits compared with the benefits produced by endogenous cues under the low load condition.