Academic journal article Canadian Journal of Experimental Psychology

Age-Related Differences in Face Processing: A Meta-Analysis of Three Functional Neuroimaging Experiments

Academic journal article Canadian Journal of Experimental Psychology

Age-Related Differences in Face Processing: A Meta-Analysis of Three Functional Neuroimaging Experiments

Article excerpt

Abstract Differences between young and old adults in brain activity, measured with positron emission tomography, were examined during three face processing experiments: episodic memory, working memory, and degraded face perception. Each experiment contained an easy face matching condition and a more difficult processing condition. Young adults showed greater activity in bilateral prefrontal cortex during the memory tasks, compared to face matching, but no difference in prefrontal activity between degraded and nondegraded perception. Older adults, on the other hand, had greater prefrontal activity in both memory and degraded perceptual tasks compared to matching. This suggests that increased prefrontal activity is task-specific in young adults, but, in old adults, is a more general response to increased cognitive effort or need for resources. These data are consistent with the dedifferentiation hypothesis of aging, and suggest a possible neural mechanism for this dedifferentiation, such that dependence on prefrontal activity across a greater number of tasks could also increase the amount of covariance across these tasks.

Aging is associated with changes in the visual system that affect contrast sensitivity and other aspects of vision (e.g., Spear, 1993). These changes, most of which are thought to be of central rather than peripheral origin (Burton, Owsley, & Sloane, 1993; Spear, Moore, Kim, Xue, & Tumosa, 1994), affect older adults, ability to detect or discriminate faces, as indexed by an increase in contrast necessary for discrimination to take place (Owsley, Sekuler, & Boldt, 1981; Sekuler & Owsley, 1982). Older adults also show reduced accuracy or increased reaction times (RTs) on tasks requiring perceptual matching of faces (Grady, McIntosh, Horwitz, & Rapoport, 2000; Grady et al., 1994). However, these perceptual differences are smaller in magnitude than age-related reductions in the ability to remember faces (Bartlett & Leslie, 1986; Bartlett, Leslie, Tubbs, & Fulton, 1989; Grady et al., 1995). Elderly individuals consistently show substantial reductions in recognition memory for unfamiliar faces (Bartlett & Leslie, 1986; Bartlett et al., 1989; Crook & Larrabee, 1992; Smith & Winograd, 1978), unless the faces are retained for very short periods of time, such as a few seconds (Grady et al., 1998). In contrast, recognition of other types of complex visual information, such as pictures of objects or scenes, is often spared or only slightly reduced compared to younger adults (Craik & Jennings, 1992; Grady, McIntosh, Rajah, Beig, & Craik, 1999; Park, Puglisi, & Sovacool, 1983; Smith, Park, Cherry, & Berkovsky, 1990).

Recently, functional neuroimaging has been used to examine the brain mechanisms underlying age-related differences in face processing. A particular region in ventral extrastriate cortex, known as the fusiform gyrus, is critically involved in face perception and memory (Andreasen et al., 1996; Bernstein, Beig, Siegenthaler, & Grady, in press; Courtney, Ungerleider, Keil, & Haxby, 1996, 1997; Haxby et al., 1994; Haxby et al., 1996; Kanwisher, McDermott, & Chun, 1997; Kuskowski & Pardo, 1999; McCarthy, Puce, Gore, & Allison, 1997; Moscovitch, Winocur, & Behrmann, 1997; Sergent, Ohta, & MacDonald, 1992), and generally shows larger increases in activity for faces than for other kinds of stimuli (Haxby et al., 1999; Kanwisher, Stanley, & Harris, 1999; Kanwisher et al., 1997). Activation in face-sensitive regions in the fusiform gyrus during face matching in older adults is equivalent to that seen in young adults (Grady et al., 1994; Grady et al., 2000). This indicates that perceptual mechanisms are largely unchanged with age, at least in terms of overall activity levels in this region of the brain. However, older individuals also show greater activation in prefrontal cortex during face perception, particularly in the left hemisphere (Grady et al. …

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