Trace and delayed heart-rate conditioning in rats as a function of US intensity.

Abstract

Examined classical conditioning of heart rate (HR) in 224 restrained naive female Long-Evans rats in a 2 * 6 factorial design involving comparisons of trace and delayed conditioning procedure and 6 UCS intensities. The CR was a deceleration in HR at each UCS intensity, with both trace and delayed conditioning. The magnitude of CR increased with UCS intensity for trace conditioning while for delayed conditioning there was an inversion in CR magnitude at UCS intensities above 1.2 ma. The UCR to shock was predominately acceleration, although at the start of acquisition it was deceleration. Results indicate that the conditioned accelerations for freely moving rats are not due to the greater subjective intensity of shock in that situation. (24 ref.) (PsycINFO Database Record (c) 2006 APA, all rights reserved)