Mental workload modulates the effects of baroreceptor afferents on sensorimotor processing

Abstract

The heart–brain interaction is the main mechanism for maintaining normative physiological processes, and its dysregulation underlies the somatic symptoms of various mental disorders. Cortical inhibition, triggered by afferent signals from baroreceptor activation, induces systematic variations in sensorimotor responses within a cardiac cycle, with reaction times (RTs) slower at cardiac systole compared to diastole (known as cardiac cycle time effects). However, recent data suggest that baroreceptor afferents not only inhibit simple responses but also facilitate complex sensorimotor responses during cardiac systole. The mental workload that is implicated in complex responses may modulate the cardiac cycle time effects. The current study aimed to examine whether concurrent mental workloads influenced cardiac cycle time effects on sensorimotor processing. Using a dual-task paradigm, 47 participants (32 female; age = 21.9 ± 2.1 years) performed a choice RT task and a working memory (WM) task. Stimuli were presented during either cardiac systole or diastole. RT data were fitted using the ex-Gaussian distribution, and the parameters, mu and tau, were derived to indicate response speed and high-order attentional processes, respectively. The behavioral data were submitted to 2 (WM load) × 2 (cardiac timing) repeated measures analyses of variances. The results indicated that RT metrics were longer during cardiac systole than diastole under the no-load condition. However, WM load reversed the cardiac timing effects on response speed while inducing more attentional lapses. These findings suggest that concurrent WM load influences cardiac cycle time effects on sensorimotor processing via top-down resources.