CHOLECYSTOKININ-INDUCED EFFECTS ON SELECTIVE ATTENTION DEPEND ON LEVEL OF ACTIVATION

Cholecystokinin (CCK)-like peptides, such as ceruletide, have been fou nd to improve selective attention as indicated by the processing negat ivity (PN) of the event-related brain potential. The present study com pared effects of ceruletide and placebo after intravenous administrati on of ceruletide on the PN in healthy subjects classified into two gro ups scoring high versus low on self-reported activation. Following pla cebo, PN (at Fz) was somewhat larger in subjects with low than high ac tivation (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 activ ation.