Abstract
We investigated age-related changes in electroencephalographic (EEG) coupling of theta-, alpha-, and beta-frequency bands during bottom–up and top–down attention. Arrays were presented with either automatic “pop-out” (bottom–up) or effortful “search” (top–down) behavior to younger and older participants. The phase-locking value was used to estimate coupling strength between scalp recordings. Behavioral performance decreased with age, with a greater age-related decline in accuracy for the search than for the pop-out condition. Aging was associated with a declined coupling strength of theta and alpha frequency bands, with a greater age-related decline in whole-brain coupling values for the search than for the pop-out condition. Specifically, prefronto-frontal coupling in theta- and alpha-bands, fronto-parietal and parieto-occipital couplings in beta-band for younger group showed a right hemispheric dominance, which was reduced with aging to compensate for the inhibitory dysfunction. While pop-out target detection was mainly associated with greater parieto-occipital beta-coupling strength compared to search condition regardless of aging. Furthermore, prefronto-frontal coupling in theta-, alpha-, and beta-bands, and parieto-occipital coupling in beta-band functioned as predictors of behavior for both groups. Taken together these findings provide evidence that prefronto-frontal coupling of theta-, alpha-, and beta-bands may serve as a possible basis of aging during visual attention, while parieto-occipital coupling in beta-band could serve for a bottom–up function and be vulnerable to top–down attention control for younger and older groups.
Highlights
Normal aging is associated with decline in the performance of a variety of cognitive functions, including effects observed in the visual search (Plude and Doussard-Roosevelt, 1989) and in the tasks involving both bottom–up attention and top–down attention, with a more prominent decline in tasks emphasizing top–down attention control (Greenwood et al, 1997; Kok, 2000; Madden et al, 2005; Madden, 2007; Lien et al, 2011; Li et al, 2013)
Mean reaction times (RTs) and accuracy rates are summarized in Table 1
There was a main effect of condition on mean RTs and accuracy rates [RTs: F(1,12) = 355.06, p < 0.0001; accuracy rates: F(1,12) = 58.46, p < 0.001], with quicker RTs and higher accuracy in the pop-out condition, and there was a main effect of target visual field only on RTs [F(1,12) = 5.06, p = 0.044], with slower RTs in the left visual field target
Summary
Normal aging is associated with decline in the performance of a variety of cognitive functions, including effects observed in the visual search (Plude and Doussard-Roosevelt, 1989) and in the tasks involving both bottom–up attention and top–down attention, with a more prominent decline in tasks emphasizing top–down attention control (Greenwood et al, 1997; Kok, 2000; Madden et al, 2005; Madden, 2007; Lien et al, 2011; Li et al, 2013). An aging study of visual attention has reported that older adults showed increased magnitude and spread of activity in frontoparietal regions compared with younger adults, suggesting a compensation for a decline in overall bottom–up sensory input (dedifferentiation; Madden et al, 2007; see reviews Reuter-Lorenz and Park, 2010). Activity decreases with aging in frontal cortex (Anderson et al, 2000; Milham et al, 2002; Johnson et al, 2004) and occipital cortex (Madden et al, 2004) were reported in attention studies, pointing to an age-related decline in allocation of attentional resources efficiency (Lorenzo-López et al, 2008) or reduction in inhibitory control functions in attention (Colcombe et al, 2003; Madden et al, 2004; Andrés et al, 2006; Hasher et al, 2008). The CRUNCH interprets these contradictory results at some degree, whereby older adults use more or new neural circuits to accomplish tasks compared to younger adults
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