Redefining the role of the default network in goal directed cognition

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The past echoes through our present and shapes our thinking about the future, guiding decisions in the moment, and framing expectations for the time ahead. Accessing past knowledge and experience during complex cognitive functions such as problem-solving, reasoning or planning is essential for adaptive human functioning. Yet the neural mechanisms that support this interaction of memory and cognitive control functions remain poorly understood. My work has shown that an assembly of functionally-connected brain regions, known as the default network, is involved in projecting oneself, in a cognitive sense, across time and space. These processes allow us to transcend our immediate environment, to reminisce about the past, and plan for the future. This suggests that the default network may play an important role in integrating memory and cognitive control processes. Yet many studies suggest just the opposite that the default network is task-negative', and suppressed during complex cognitive tasks. This may be an artifact of laboratory studies which typically use stimuli devoid of personal meaning, and thus fail to engage the default network. My recent research, utilizing personally-meaningful stimuli during a cognitive control task, suggests that the default network, far from being task-negative', is an active attentional system linking memory and cognitive control. The current proposal will extend this work, providing the first systematic investigation of default network involvement in cognitive control. Using functional neuroimaging methods, initial studies will identify the specific determinants of default network activity during cognitive control tasks. A second series of studies will directly investigate how disrupting default network activity, using neurostimulation methods, impacts cognitive control performance. Defining the role of the default network in integrating memory and cognitive control will advance our understanding of how complex human behaviors are implemented in the brain. Further, the default network is susceptible to disruption in aging and brain disease. While not directly investigated here, the proposed research may provide critical insights linking altered default network functioning to changes in cognitive control in older adulthood. This would identify novel avenues for investigating neural mechanisms associated with age related cognitive decline.