Hippocampal acetylcholine efflux increases during negative patterning and elemental discrimination in rats.

The purpose of this paper is to examine whether hippocampal acetylcholine (ACh) efflux increases during negative patterning (NP) discrimination tasks. For these tasks, a rat's response was rewarded when either a single stimulus A (tone) or stimulus B (light) was presented, but was not rewarded when the compound stimulus AB (tone+light) was presented to the NP group of rats. An elemental discrimination (E) task was given to another group (E group).