How does the brain's spontaneous activity generate our thoughts? The spatiotemporal theory of task-unrelated thought (STTT)

Recent investigations have demonstrated the psychological features (e.g. cognitive, affective, and social) of task- unrelated thoughts, as well as their underlying neural correlates in spontaneous activity, which cover various networks and regions, including the default- mode and central executive networks. Despite impressive progress in recent research, the mechanisms by means of which the brain's spontaneous activity generates and constitutes thoughts remain unclear. This chapter suggests that the spatiotemporal structure of the brain's spontaneous activity can integrate both content- and process- based approaches to task- unrelated or spontaneous thought- this amounts to what is described as the "spatiotemporal theory of task- unrelated thought" (STTT). Based on various lines of empirical evidence, the STTT postulates two main spatiotemporal mechanisms, spatiotemporal integration and extension. The STTT provides a novel brain- based spatiotemporal theory of task- unrelated thought that focuses on the brain's spontaneous activity, including its spatiotemporal structure, which allows integrating content- and process- based approaches.