ERPs and the evoked cardiac response to auditory stimuli: Intensity and cognitive load effects.

The evoked cardiac response (ECR) may be described as the sum of two independent response components: an initial HR deceleration (ECR1) and a slightly later acceleration (ECR2) hypothesized to reflect stimulus registration and cognitive processing load, respectively. This study investigated processing load effects in the ECR and the event-related potential (ERP). Stimulus intensity was varied within subjects, and cognitive load was varied between subjects, in a counting/no counting task with a long interstimulus interval. The ECR showed a significant effect of counting, but not intensity. ERPs showed the expected obligatory processing effects in the N1, and substantial effects of cognitive load in the Late Positive Complex. Both ERP components varied with intensity. These novel data offer support for ANS-CNS similarities in reflecting some aspects of stimulus processing, but further work is needed to understand the possible contribution of ERP subcomponents to these effects.