Representing Representation: Integration between the Temporal Lobe and the Posterior Cingulate Influences the Content and Form of Spontaneous Thought.

Spontaneous thoughts about absent people, places, or events arise from interactions within the default mode network (DMN). The posterior cingulate cortex, a core DMN region, integrates information from medial and lateral temporal lobe memory systems, which represent different aspects of knowledge. Individual differences in connectivity between temporal lobe regions and the DMN core predict the content and form of people's spontaneous thoughts. In a laboratory study, variations in functional connectivity from both medial and lateral temporal lobe regions were associated with different patterns of spontaneous thought, converging on an overlapping region in the posterior cingulate cortex. The posterior DMN core acts as a representational hub that integrates temporal lobe information, shaping spontaneous thought.

Study at a glance

Abstract

When not engaged in the moment, we often spontaneously represent people, places and events that are not present in the environment. Although this capacity has been linked to the default mode network (DMN), it remains unclear how interactions between the nodes of this network give rise to particular mental experiences during spontaneous thought. One hypothesis is that the core of the DMN integrates information from medial and lateral temporal lobe memory systems, which represent different aspects of knowledge. Individual differences in the connectivity between temporal lobe regions and the default mode network core would then predict differences in the content and form of people's spontaneous thoughts. This study tested this hypothesis by examining the relationship between seed-based functional connectivity and the contents of spontaneous thought recorded in a laboratory study several days later. Variations in connectivity from both medial and lateral temporal lobe regions was associated with different patterns of spontaneous thought and these effects converged on an overlapping region in the posterior cingulate cortex. We propose that the posterior core of the DMN acts as a representational hub that integrates information represented in medial and lateral temporal lobe and this process is important in determining the content and form of spontaneous thought.