Cognitive flexibility and fronto-parietal control dynamics in aging

Baniqued, Pauline

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https://hdl.handle.net/2142/73076 Copy

Description

Title

Cognitive flexibility and fronto-parietal control dynamics in aging

Author(s)

Baniqued, Pauline

Issue Date

2015-01-21

Director of Research (if dissertation) or Advisor (if thesis)

• Fabiani, Monica
• Gratton, Gabriele

Doctoral Committee Chair(s)

Kramer, Arthur

Committee Member(s)

• Fabiani, Monica
• Gratton, Gabriele
• Beck, Diane
• Cohen, Neal J.

Department of Study

Psychology

Discipline

Psychology

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• cognitive aging
• executive function
• fronto-parietal network

Abstract

How do we prepare for complex tasks? Can we optimize preparatory control processes, especially as they decline with age? The research program detailed here sheds light on these questions by employing integrative paradigms to investigate brain dynamics related to successful performance in attention or control-demanding situations. These control-demanding processes are broadly referred to as “executive functions,” known to heavily involve the frontal cortex. The relationship between frontal brain activity and behavioral performance however, is not straightforward. Some studies find that increased activation in this region relates to better performance, while others, particularly studies that involve older adults, show that increased activation can also indicate failure to engage appropriate control processes. Given these mixed observations, as well as the myriad of areas involved in any complex task, research has increasingly shifted towards understanding how brain processes are implemented via activity in a set of networked regions, with the main idea that correlation of activity or “connectivity” between regions is more informative than activity from a single region. Moreover, studies have shown that factors such as aging, as well as training or interventions do not only change the structure or activity of specific regions, but the dynamics of the brain networks these regions belong to. This dissertation involves two main goals: 1) investigating preparatory control processes by evaluating the connectivity of brain regions, particularly the interaction of the prefrontal cortex and task-relevant regions, and 2) investigating how aging may modify the dynamics of these processes, with future plans to use these findings to inform training or intervention research. In the first experiment (Chapter 2), I investigate preparatory processes in middle-to-older aged adults using a cued task-switching paradigm. Older adults show a specific decline in fronto-parietal regions and in executive function abilities, particularly in tasks that involve flexibly allocating attention. Here, in addition to age, corpus callosum and modulation over left frontal cortex predicted switch costs. Using cross-correlations to examine the flow of activity in a switching task, I found that left middle frontal gyrus activity preceded up-regulation of task-relevant lateralized processes in frontal regions. In addition to highlighting the flexible dynamics and timing of these processes, this experiment also confirmed the importance of the corpus callosum structural connection in supporting the task-dependent interaction between frontal regions. In the second experiment (Chapters 3 and 4), I examine preparatory control by studying whether older adults modulate frontal control processes in response to cues that indicate the degree of control needed for an upcoming target stimulus. Similar to young adults, older adults showed cue-related behavioral adjustments and up-regulated frontal regions for cues predicting a greater need for attentional control. Lagged cross-correlations showed that control-demanding cues led to greater coupling between the dorsal anterior cingulate cortex and the left middle frontal gyrus, regions important for evaluating control and implementing control, respectively. Although older adults showed weaker and trends for slower up-regulation of frontal regions overall, they also showed greater bilateral recruitment of dorsal frontal regions, with cross-correlations pointing to a left-to-right hemisphere flow of activation and up-regulation during the control-demanding cues. Overall, this line of work uses converging behavioral and imaging methods to obtain a more comprehensive view of the brain dynamics that are important for complex performance. Chapter 5 integrates the findings from the two experiments to identify common mechanisms of preparatory control and age-related change. Identifying the neural processes that are important for executive function can better inform research that seeks to maintain or improve this ability across the lifespan. Potential applications include monitoring brain activity and providing real-time feedback to support performance, and identifying tasks or interventions that promote and engage the neurocognitive dynamics that are important for performance in real-world tasks.

Graduation Semester

2014-12

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http://hdl.handle.net/2142/73076

Copyright and License Information

Copyright 2014 Pauline Baniqued

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