Intranasally administered Cholecystokinin decreases controlled memory

The neuropeptide Cholecystokinin (CCK) is involved in the modulation of memory processes. In this study, we examined for the first time the effect of intranasally administered CCK on controlled recollection and automatic familiarity in humans. To separate controlled from automatic memory processes, we used a modified version of Jacoby's process dissociation procedure (1991). Immediately after two successive learning phases, which are necessary for the implementation of the procedure, half of the participants received CCK, the other half a placebo solution. Recognition was tested 30 min after the learning phases. CCK decreased controlled recollection but not automatic familiarity when compared to placebo. Behavioral, physiological, and subjective control variables were not affected by the peptide. The results indicate a differential effect of CCK on controlled memory processes. Either consolidation and/or retrieval of verbal material are impaired.