In dogs with elaborated rhythmic and mozaic stereotypes of secretory and motor situational conditioned reflexes specific features were revealed in the action of some neurotropic drugs (amizyl, amedine, diphacil, pediphene, chlorpromazine and sodium oxybutyrate) on preparatory (latent) conditions of excitation and inhibition, appearing in the stabilized systems of reflexes. Pharmacological analysis has pointed to the predominantly cholinergic nature of preparatory and trigger mechanisms of alimentary conditioned activity. The blockade of M-cholinoreceptors (by means of amizyl and amedine) weakens or eliminates the preparatory conditions appearing in a dynamic stereotype and disturbs the trigger reactions within three to ten days. A pediphene blockade of H-cholinoreceptors intensifies the preparatory states.