[O-15-butanol Pet activation study on the cerebral representation of declarative memory]

In this study, neuroanatomical correlates of encoding and retrieval in paired associate learning were evaluated with positron emission tomography using auditorily presented highly imaginable words.

Six right-handed normal male volunteers took part in the study. Each subject underwent six O-15-butanol PET scans. On each of the six trials the memory task began with the injection of a bolus of O-15-butanol. The subjects had to learn and retrieve twelve word pairs (highly imaginable words, not semantically related). The presentation of nonsense words served as reference condition.

Recall accuracy after 2-4 presentations was high during the PET measurement. In both encoding and retrieval we found anterior cingulate activation. We show bilateral dorsolateral prefrontal activation during the encoding of auditorily presented word pair associates, whereas retrieval led to left frontal activation. Furthermore, we demonstrate the importance of the precuneus in the retrieval of highly imaginable word-pair associates.

Our results support the hypothesis of the presence of distributed widespread brain structures subserving episodic declarative memory.