Sensory representations supporting memory specificity: Age effects on behavioral and neural discriminability

Older adults’ difficulty in distinguishing between old and new information contributes to memory decline, which may occur because older adults are less likely than young adults to retrieve specific sensory details necessary to distinguish between similar items. In male and female human subjects, the present study measured the extent of age differences in the specificity of memory representations using a false memory paradigm in which studied items were linked to retrieval items at multiple levels of similarity. Older adults showed poorer behavioral discrimination than young adults, driven primarily by false recognition of lures that differed from targets only in perceptual details. Patterns of activation across several regions within ventral visual cortex could be used to distinguish between targets and lures when they differed in both perceptual details and a semantic label. However, of ventral visual regions, only signals in the midline occipital cortex could be used to distinguish targets from lures when they differed only in perceptual details. Although there was an overall age deficit for this neural discrimination in this region, the positive relationship between neural and behavioral discriminability did not differ across age groups. In contrast, age moderated the relationship between neural and behavioral discriminability in lateral occipital and fusiform cortices, suggesting that activation patterns within these regions represent different types of information in each age group. Therefore, the quality of perceptual signals is a key contributor to memory discrimination across age groups, with evidence that age differences in the nature of representations emerges outside early visual cortex.