Cholecystokinin-induced effects on selective attention depend on level of activation

Cholecystokinin (CCK)-like peptides, such as ceruletide, have been found to improve selective attention as indicated by the processing negativity (PN) of the event-related brain potential. The present study compared effects of ceruletide and placebo after intravenous administration of ceruletide on the PN in healthy subjects classified into two groups scoring high versus low on self-reported activation. Following placebo, PN (at Fz) was somewhat larger in subjects with low than high activation (p < 0.1). Administration of the CCK analog decreased PN in low-activation subjects but increased PN in the highly activated group (p < 0.01). Results suggest that the effects of CCK on selective attention depend on a modulation of central nervous mechanisms underlying activation.