Cognitive flexibility and fronto-parietal control dynamics in aging

by Pauline Baniqued

Institution: University of Illinois – Urbana-Champaign
Department: 0338
Degree: PhD
Year: 2015
Keywords: cognitive aging
Record ID: 2060761
Full text PDF: http://hdl.handle.net/2142/73076


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…