The empirical study of spontaneous cognitions— unprompted and unintentional explicit mental representations that come to mind spontaneously—has been gaining increasing traction in recent years. Humans spend half their waking time engaging in these spontaneous cognitions or mind-wandering with studies providing support for mind-wandering to be linked with adaptive and maladaptive functional outcomes. However, despite this being a ubiquitous phenomenon, there is considerable debate in the literature on the definition of mind-wandering, associated neural correlates, and implications for cognitive and brain health. In this symposium, we bring together four presenters, who employ variegated experimental methods and definitions to understand the neural correlates of this elusive construct of mind-wandering. Through carefully designed methods, the four presenters also investigate the implications of engaging in task-unrelated thoughts for creativity, rumination, psychological health, and cognitive functioning in healthy and pathological aging.

Orwig et al. examine neural correlates of intentional vs. unintentional mind wandering. Their results support a differential involvement of posterior cortices in intentional mind wandering whereas unintentional mind wandering involved the top-down regulatory nodes of the prefrontal cortices. Interestingly, both intentional and unintentional mind wandering was associated with creative thinking thus providing support for mind wandering as an adaptive process. Andrews-Hanna et al. have developed a novel think aloud technique where participants are asked to voice aloud their thoughts in real time across rest periods in the lab, the MRI scanner, and in participants own homes. Across several contexts, they found participants to show a high degree of similarity in resting thought. They also report significant individual differences content and dynamic characteristics of resting thought. Importantly, trait levels of rumination were associated with resting state thought patterns characteristic of brooding—negative, self-focused, and past-oriented thoughts. Individual differences in creativity, in contrast, were associated with loosely associative thoughts that exhibited a pattern of exploration. Prakash & Teng demonstrate the first empirical test of a direct relationship between mind-wandering and fluid-based biomarkers of amyloid and tau pathology in 289 older adults from the Alzheimer's Disease Neuroimaging Initiative. The neuromarker of mind-wandering— representing edges associated with a high degree of off-task thinking—was positively associated with a high CSF p-tau/Aß42 ratio (indicative of higher levels of pathology). Moreover, network strength in the high mind-wandering model was also associated with lower global cognition, lower executive functioning, and episodic memory.

O'Callaghan et al. examine dysfunctional mind-wandering in neuropsychiatric diseases of aging: frontotemporal dementia, Alzheimer's disease, and Parkinson's disease. Employing a thought-sample task to probe mind-wandering, they show evidence of reduced mind-wandering in individuals with fronto-temporal dementia and Parkinson's disease. They also provide evidence that the hippocampal sharp wave-ripple is a compelling candidate for a brain state that can trigger mind-wandering episodes.