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Abstract:
To investigate age-related differences in the neural
correlates of memory and attention, we conducted PET activation
study using divided attention paradigm. Twelve young and twelve old
healthy volunteers were involved after giving informed consent. The
subject performed memory task (encoding and retrieval of visually
presented word-pairs) and auditory pitch discrimination task (full
and divided attention condition) concurrently. Cerebral blood flow
was measured using standard O-15 water bolus infusion method, and
the image data were analyzed by SPM96. Behavioural results showed
that divided attention (DA) during encoding reduced memory
accuracy, but DA during retrieval did not. PET results in the young
demonstrated that DA activated bilateral auditory area, left
prefrontal cortex, left anterior cingulate gyrus, and cerebellum,
whereas it deactivated left inferior temporal gyrus, visual area,
and bilateral inferior frontal gyrus. The effect of DA during
retrieval was minimal. The old subject, as compared to the young,
activated right secondary auditory area and prefrontal cortex,
suggesting that the old was more greatly distracted by auditory
task than the young. Reduced activity in left prefrontal cortex
during encoding and right precuneus during retrieval may account
for memory impairment in the old subject.
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