Aging Does Not Affect Brain Patterns of Repetition Effects Associated with Perceptual Priming of Novel Objects

Abstract

This study examined how aging affects the spatial patterns of repetition effects associated with perceptual priming of unfamiliar visual objects. Healthy young (N=14) and elderly adults (N=13) viewed four repetitions of structurally possible and impossible figures while being scanned with BOLD fMRI. Although explicit recognition memory for the figures was reduced in the elder subjects, repetition priming did not differ across the two age groups. Using multivariate linear modeling, we found that the spatial networks of regions that demonstrated repetition-related increases and decreases in activity were identical in both age groups, although there was a trend for smaller magnitude repetition effects in these networks in the elder adults for objects that had been repeated three times. Furthermore, repetition-related reductions in activity in left inferior frontal cortex for possible objects correlated with repetition-related facilitation in reaction time across both young and elder subjects. Repetition-related increases of an initially negative response were observed for both object types in both age groups in parts of the default network, suggesting that less attention was required for processing repeated stimuli. These findings extend prior studies using verbal and semantic picture priming tasks and support the view that perceptual repetition priming remains intact in later adulthood because the same spatial networks of regions continue to show repetition-related neural plasticity across the adult life span.

Real-Time Neural Signals of Perceptual Priming with Unfamiliar Geometric Shapes

“…The current findings diverge from fMRI findings showing greater neural activity for repetition of unfamiliar faces, meaningless symbols, and pseudowords, whereas repetition of familiar stimuli produces less activity (Henson et al, 2000;Fiebach et al, 2005;Soldan et al, 2008). James and Gauthier (2006) argued that the priming literature, showing reduced activity sometimes and enhanced activity other times, can best be explained by an accumulation model that describes the temporal dynamics of neural activity.…”

“…Observing negative repetition effects (both negative ERP old/new effects and fMRI deactivations) may require negligible explicit memory. Explicit retrieval was not strongly discouraged in previous studies that found positive repetition effects with unfamiliar stimuli (Henson et al, 2000;Fiebach et al, 2005;Soldan et al, 2008). Indeed, the first neuroimaging study to identify increased ventral visual activity for priming of unfamiliar objects also showed highly accurate explicit recognition in the same circumstances, with concomitant hippocampal activation for both priming and recognition attributed to explicit retrieval (Schacter et al, 1995).…”

“…In contrast, priming for unfamiliar stimuli occurs with greater neural activity in many of these same brain regions (Henson et al, 2000;Fiebach et al, 2005;Soldan et al, 2008), and these effects have been attributed to perceptual learning. However, it is unclear whether activity enhancements for unfamiliar stimuli reflect perceptual learning, implicit memory, or explicit memory.…”

Alzheimer's disease and implicit memory

“…however, each process has separate mechanisms 26,30,31 . Priming is influenced by frontal cortex, which may reflect its attentional demands [32][33][34] and procedural memory is influenced by the striatum, sensorimotor cortex and cerebellum 30,35,36 , which may reproduce its motor skills. explicit memory impairment is one of the earliest AD symptoms, and its loss characterizes all the stages of AD 37 .…”

Dissociable Forms of Repetition Priming: A Computational Model

“…For instance, Henson et al (2000) has shown that the repetition of truly unfamiliar visual stimuli, such as unfamiliar faces and symbols, could lead to an increase in neural activity in the right fusiform region measured as an fMRI signal, while repeated exposure to familiar stimuli elicits decaying activity. Similarly, Soldan, Gazes, Hilton, and Stern (2008) have registered repetition enhancement in the occipital-temporal cortex related to the repetition of unfamiliar stimuli and decreases in neural activity for familiar stimuli. A study by Fiebach, Gruber, and Supp (2005) presented similar EEG results showing dissociable trends for the repetition of familiar words versus unfamiliar pseudowords.…”