[Show abstract][Hide abstract] ABSTRACT: The size of the functional field of view (FFOV) predicts driving safety in older adults (
Owsley et al., 1998), and practice-related changes in the FFOV may transfer to driving safety (
Roenker, Cissell, Ball, Wadley, & Edwards, 2003). We used functional magnetic resonance imaging (fMRI) and behavioral measures to examine how practice with the FFOV task
changes older adults' attentional function. Behavioral data collected outside of the MRI revealed that participants in the
training group showed larger improvements across conditions than did those in the control group. fMRI data revealed training-related
changes in activation in a number of brain regions. In the right precentral gyrus and right inferior frontal gyrus, increases
in activation between fMRI sessions correlated positively with increases in accuracy between behavioral sessions. Practice
with the FFOV task improves older adults' attentional function by increasing their recruitment of regions traditionally associated
with orienting visual attention.
Full-text · Article · Jun 2007 · The Journals of Gerontology Series B Psychological Sciences and Social Sciences
[Show abstract][Hide abstract] ABSTRACT: The extent to which cortical plasticity is retained in old age remains an understudied question, despite large social and scientific implications of such a result. Neuroimaging research reports individual differences in age-related activation, thereby educing speculation that some degree of plasticity may remain throughout life. We conducted a randomized longitudinal dual-task training study to investigate if performance improvements (a) change the magnitude or pattern of fMRI activation, thereby suggesting some plasticity retention in old age and (b) result in a reduction in asymmetry and an increase in age differences in fMRI activation as a compensatory model of performance-related activation predicts. Performance improvements were correlated with an increase in hemispheric asymmetry and a reduction in age differences in ventral and dorsal prefrontal activation. These results provide evidence for plasticity in old age and are discussed in relation to an alternative argument for the role of reduced asymmetry in performance improvements.
Full-text · Article · Mar 2007 · Neurobiology of aging
[Show abstract][Hide abstract] ABSTRACT: Although training-induced changes in brain activity have been previously examined, plasticity associated with executive functions remains understudied. In this study, we examined training-related changes in cortical activity during a dual task requiring executive control. Two functional magnetic resonance imaging (fMRI) sessions, one before training and one after training, were performed on both a control group and a training group. Using a region-of-interest analysis, we examined Time x Group and Time x Group x Condition interactions to isolate training-dependent changes in activation. We found that most regions involved in dual-task processing before training showed reductions in activation after training. Many of the decreases in activation were correlated with improved performance on the task. We also found an area in the dorsolateral prefrontal cortex that showed an increase in activation for the training group for the dual-task condition, which was also correlated with improved performance. These results are discussed in relation to the efficacy of training protocols for modulating attention and executive functions, dual-task processing, and fMRI correlates of plasticity.
[Show abstract][Hide abstract] ABSTRACT: Previous dual-task neuroimaging studies have not discriminated between brain regions involved in preparing to make more than one response from those involved in the management and execution of two tasks. To isolate the effects of dual-task processing while minimizing effects related to task-preparatory processes, we employed a blocked event-related design in which single trials and dual trials were randomly and unpredictably intermixed for one block (mixed block) and presented in isolation of one another during other blocks (pure blocks). Any differences between dual-task and single-task trials within the mixed block would be related to dual-task performance while minimizing any effects related to preparatory differences between the conditions. For this comparison, we found dual-task-related activation throughout inferior prefrontal, temporal, extrastriate, and parietal cortices and the basal ganglia. In addition, when comparing the single task within the mixed block with the single task presented in the pure block of trials, the regions involved in processes important in the mixed block yet unrelated to dual-task operations could be specified. In this comparison, we report a pattern of activation in right inferior prefrontal and superior parietal cortices. Our results argue that a variety of neural regions remain active during dual-task performance even after minimizing task-preparatory processes, but some regions implicated in dual-task performance in previous studies may have been due to task-preparation processes. Furthermore, our results suggest that dual-task operations activate the same brain areas as the single tasks, but to a greater magnitude than the single tasks. These results are discussed in relation to current conceptions of the neural correlates of dual-task performance.