Blink-related dynamic switching between internal and external orienting networks while viewing videos.

Humans spontaneously generate eyeblinks every few seconds. However, because this blink rate is several times more common than is required for ocular lubrication, the function of most spontaneous eyeblinks remains unknown. Because spontaneous eyeblinks tend to occur at implicit breakpoints in video stories, I hypothesized that spontaneous eyeblinks play an active role in attentional disengagement from external stimuli. Consistent with this, we previously found that spontaneous eyeblinks involve the concurrent deactivation of the dorsal attention network and activation of the default mode network when individuals are viewing videos. However, this previous study examined only the upper brain regions to increase the temporal resolution of the data. Therefore, the present study examined whether the temporal and subcortical regions exhibited blink-related activations or deactivations using the same visual stimuli as in the previous study. Data revealed that the bilateral hippocampus and cerebellum showed a prominent but momentary activation after the blink onset. In contrast, a blink-related deactivation was observed in both the right ventral and dorsal attention networks. These results suggest that spontaneous eyeblinks are involved in the attentional disengagement from external visual information via the massive and dynamic alteration of brain activity between the external and internal orienting networks.