They also conducted between-subject analyses to identify brain regions that demonstrated either a monotonic increase or decrease in activation magnitude, and correlated the blood oxygen level-dependent changes scores on the delayed portion of the California Verbal Learning Test.
They found that the controls had greater activation during novel encoding tasks than in familiar encoding tasks in the dorsolateral prefrontal, lateral parietal, and medial temporal regions. Controls also had deactivation, or reduced activity, that was greater during familiar encoding than in novel encoding in the midline frontal and parietal regions.
"Along the spectrum from control subjects to patients with Alzheimer's disease, there was decreasing activation in the medial temporal lobe, including the hippocampus and parahippocampal and fusiform gyri, and increasing activation in the posteromedial cortices primarily in the precuneus and posterior cingulate gyrus," the authors wrote.
When they compared the verbal learning scores with the images, they found that the magnitude of activation in the posteromedial corticies correlated significantly with scores (P<0.001, r=-0.502).