Behavior induction by brain extracts: a comparison of two procedures.

Induction of behavior by chemical extracts of trained rat brain has been observed in two types of choice situations. (1) In a symmetric (left/right) choice situation, the induced bias may be either positively or negatively related to that learned by the donors, depending strongly upon dosage and the exact experimental conditions. This makes the effect unstable and difficult to replicate with this procedure. Inversion effects appear to predominate in the observed dosage range. (2) In an asymmetric (two-chamber) choice situation, differing in operant tasks, wall colors, and other cues, a consistently positive effect with a simpler dose dependence was observed. The difference between these two cases is attributed to the lack of specific stimuli identifying the behavioral choices in the symmetric situation, and the abundance of specific stimulus cues in the asymmetric case.