Age related changes in top-down modulation of low-level visual processing.
Zanto, T., Toy, B., Gazzaley, A. Cognitive Neuroscience Meeting (2008)

Top-down modulation refers to our ability to focus attention on task-relevant stimuli while ignoring irrelevant distractions and it shares an intimate relationship with memory, as the focus of attention will restrict content to relevant information and limit interference from irrelevant stimuli. In the current study, we assessed the influence of aging on the relationship between top-down modulation during low-level (i.e. color or motion) visual processing and working memory (WM), as it has been shown that older adults exhibit slower processing speeds and deficits in WM and attention. Subjects were between 18-35 y.o. and 60-80 y.o. Both age groups were presented sequential, random-dot circular apertures that contained stationary colored dots or gray dots that moved coherently in one direction. Each trial contained two different directions of motion and two different colors followed by a four second delay and a probe stimulus. Subjects were given four task conditions:  remember the directions of motion (ignore color), remember the colors (ignore motion), remember both directions and colors, or passively view all stimuli. All subjects were pre-thresholded for discrimination and performance measures revealed a significant age-related decrease in WM for color, but an increased RT for both color and motion. Attentional (top-down) modulation was observed in posterior electrodes and did not differ in magnitude between the age groups. However, older subjects displayed longer reaction times and delayed neural responses as indexed by a shift in the selection negativity and alpha desynchronization. The relationship between delayed neural modulation and WM performance is being further explored.