Age-related changes in neural activity during performance matched working memory manipulation

Abstract

A long-standing assumption in the cognitive aging literature is that performance on working memory (WM) tasks involving serial recall is relatively unaffected by aging, whereas tasks that require the rearrangement of items prior to recall are more age-sensitive. Previous neuroimaging studies of WM have found age-related increases in neural activity in frontoparietal brain regions during simple maintenance tasks, but few have examined whether there are age-related differences that are specific to rearranging WM items. In the current study, older and younger adults' brain activity was monitored using functional magnetic resonance imaging (fMRI) as they performed WM tasks involving either maintenance or manipulation (letter-number sequencing). The paradigm was developed so that performance was equivalent across age groups in both tasks, and the manipulation condition was not more difficult than the maintenance condition. In younger adults, manipulation-related increases in activation occurred within a very focal set of regions within the canonical brain WM network, including left posterior prefrontal cortex and bilateral inferior parietal cortex. In contrast, older adults showed a much wider extent of manipulationrelated activation within this WM network, with significantly increased activity relative to younger adults found within bilateral PFC. The results suggest that activation and age-differences in lateral PFC engagement during WM manipulation conditions may reflect strategy use and controlled processing demands rather than reflect the act of manipulation per se.

Transformations in oscillatory activity and evoked responses in primary somatosensory cortex in middle age: A combined computational neural modeling and MEG study

“…This prediction is consistent with a prominent theme that emerges from the fMRI literature on aging: When compared to YA, older adults tend to show increased activation of high-order association cortices, including prefrontal cortex, when performing a variety of cognitive and perceptual tasks (Cabeza, 2002; Grady et al, 1994; Onozuka et al, 2003; Fernandes et al, 2006; Emery et al, 2008). While it is difficult to bridge findings from fMRI and MEG/EEG studies, it is possible that a generalized increase in association cortex activity could provide the necessary FB enhancement to drive the greater M70 peak seen in our MEG and modeling data.…”

Inter-individual differences in resting-state functional connectivity predict task-induced BOLD activity

“…Consistent with Cohen et al’s observation linking the boundaries of task-based activations and functional regions defined using RSFC, our analyses suggest that inter-individual differences in the spatial extent of task-induced activations are governed by the same mechanisms that undergird RSFC networks (Steyn-Ross et al, 2009). This finding further supports the potential utility of resting-state approaches to study the developing (< 18 year old) and aging (> 65 year old) brain, which are both characterized by greater spatial extent of activation and RSFC (Andrews-Hanna et al; Durston et al, 2006; Emery et al, 2008; Fair et al, 2008; Fair et al, 2007; Kelly et al, 2009a). These observations may also provide candidate biomarkers for clinical populations in which pathological processes appear to impact the spatial extent of task-induced activations (e.g., autism, ADHD) (Durston et al, 2003; Mostofsky et al, 2006).…”

Motor control and aging: Links to age-related brain structural, functional, and biochemical effects

“…Indeed, older adult brains typically follow patterns of underactivation relative to young adults during memory, cognitive control and executive processing. In contrast, older adults show greater activation when performing tasks that engage executive functions, episodic memory, and working memory tasks when compared to young adults (Emery et al, 2008; Morcom et al, 2003; 2007; Reuter-Lorenz et al, 2000; Rypma & D'Esposito, 2000). These cognitive findings have recently been extended into the motor control literature, with one interesting exception -- studies utilizing motor tasks do not report areas of underactivation in older adults (Calautti et al, 2001; Heuninckx et al, 2005; 2008; Mattay et al, 2002; Ward & Frackowiak 2003).…”