Abstract
Executive functions, a set of cognitive processes that enable flexible behavioral control, are known to decay with aging. Because such complex mental functions are considered to rely on the dynamic coordination of functionally different neural systems, the age‐related decline in executive functions should be underpinned by alteration of large‐scale neural dynamics. However, the effects of age on brain dynamics have not been firmly formulated. Here, we investigate such age‐related changes in brain dynamics by applying “energy landscape analysis” to publicly available functional magnetic resonance imaging data from healthy younger and older human adults. We quantified the ease of dynamical transitions between different major patterns of brain activity, and estimated it for the default mode network (DMN) and the cingulo‐opercular network (CON) separately. We found that the two age groups shared qualitatively the same trajectories of brain dynamics in both the DMN and CON. However, in both of networks, the ease of transitions was significantly smaller in the older than the younger group. Moreover, the ease of transitions was associated with the performance in executive function tasks in a doubly dissociated manner: for the younger adults, the ability of executive functions was mainly correlated with the ease of transitions in the CON, whereas that for the older adults was specifically associated with the ease of transitions in the DMN. These results provide direct biological evidence for age‐related changes in macroscopic brain dynamics and suggest that such neural dynamics play key roles when individuals carry out cognitively demanding tasks.
Highlights
Normal aging is associated with the decline in many mental functions which affects older adults’ quality of life (Davis et al, 2010)
After pooling the binarized fMRI data across the participants in each age group, we fitted the pairwise maximum entropy model (MEM) for each age group and each system (i.e., default mode network (DMN) or cingulo-opercular network 10 (CON)) and found that in all the cases, the model accurately fitted to the empirical fMRI signals
0.05), whereas the younger adults did not (t25 = –0.26, P = 0.80). These results suggest that the executive ability of younger adults is related to the efficiency in brain dynamics of the CON rather than that of the DMN, whereas the executive ability of older adults relies on the DMN efficiency rather than on the CON efficiency
Summary
Normal aging is associated with the decline in many mental functions which affects older adults’ quality of life (Davis et al, 2010). Older adults, relative to younger adults, are more distracted by task-irrelevant information, such as their internal thoughts and external events (Hasher et al, 1991; Gazzaley et al, 2005). These results suggest that transitions from one state to another may happen too frequently in the older-aged brain as well as in older adults’ behavior
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