The neural basis of intrusions in free recall and cued recall: a PET study in Alzheimer’s disease.

This study was designed to map in Alzheimer’s disease patients the correlations between resting-state brain glucose utilization measured by PET and the number of intrusions obtained by means of a specially designed episodic memory test separately in free recall and in cued recall. SPM revealed significant negative correlations between the number of intrusions in free recall and the metabolism of the right superior frontal gyrus. For the intrusions in cued recall, the negative correlations concerned the left rhinal cortex. Our findings suggest that intrusions in free recall reflect perturbations in strategic processes and that intrusions in cued recall are triggered by the cue in a relatively automatic manner. Frontal dysfunction would be responsible for the former and rhinal dysfunction for the latter.