adults than younger adults in the regions of brain that are recruited to
carry out a variety of cognitive tasks (Cabeza, 2001). One suggested
explanation for this finding is that older adults recruit additional cortical
areas to compensate for losses in neural efficiency. Another view
characterizes dedifferentiation as a simple marker of cognitive decline.
Some evidence in support of the compensatory hypothesis has
been provided by studies that have examined the relationship between
performance and brain activation. For example, Rympa and D’Esposito
(2000) found, in an event-related fMRI study, that higher levels of activation
of dorsolateral prefrontal cortex were associated with faster
working memory retrieval for older adults.
Longitudinal assessments of cardiovascular changes and neurocognitive
functioning would allow one to test the role that dedifferentiation
plays in normal aging more directly. Such assessments would
enable researchers to determine whether improvements in cognitive
function that result from enhanced cardiovascular fitness would lead
older adults to become more dissimilar from younger adults in their
patterns of brain activation (i.e., increased dedifferentiation). Alternatively,
cardiovascular improvements might “turn back the clock,” biologically
speaking, and lead to patterns of neural activation that are
more similar to the pattern of young adults.
The finding of significant effects for programmatic and demographic
moderators also provides important information concerning
potential boundary conditions on the fitness-cognition relationship,
and suggests additional questions for further research. For example, it
will be important to determine whether the larger fitness benefit for
older than for younger senior citizens is the result of age differences in
general health or education, or is instead a function of baseline cogni
adults than younger adults in the regions of brain that are recruited to
carry out a variety of cognitive tasks (Cabeza, 2001). One suggested
explanation for this finding is that older adults recruit additional cortical
areas to compensate for losses in neural efficiency. Another view
characterizes dedifferentiation as a simple marker of cognitive decline.
Some evidence in support of the compensatory hypothesis has
been provided by studies that have examined the relationship between
performance and brain activation. For example, Rympa and D’Esposito
(2000) found, in an event-related fMRI study, that higher levels of activation
of dorsolateral prefrontal cortex were associated with faster
working memory retrieval for older adults.
Longitudinal assessments of cardiovascular changes and neurocognitive
functioning would allow one to test the role that dedifferentiation
plays in normal aging more directly. Such assessments would
enable researchers to determine whether improvements in cognitive
function that result from enhanced cardiovascular fitness would lead
older adults to become more dissimilar from younger adults in their
patterns of brain activation (i.e., increased dedifferentiation). Alternatively,
cardiovascular improvements might “turn back the clock,” biologically
speaking, and lead to patterns of neural activation that are
more similar to the pattern of young adults.
The finding of significant effects for programmatic and demographic
moderators also provides important information concerning
potential boundary conditions on the fitness-cognition relationship,
and suggests additional questions for further research. For example, it
will be important to determine whether the larger fitness benefit for
older than for younger senior citizens is the result of age differences in
general health or education, or is instead a function of baseline cogni
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