[Cardiovascular responses during two kinds of mental arithmetic tasks].

Eighteen young females performed two kinds of mental tasks, an Internally-Generated Mental Arithmetic task (IGMA: serial subtraction) and an Externally-Presented Mental Arithmetic task (EPMA: continual subtraction). Both tasks were equal in establishing active coping, but EPMA made participants attend more to an external stimulus. The expected reaction patterns were vascular-dominant (blood pressure elevation mainly due to an increase in total peripheral resistance) for only EPMA, or cardiac-dominant (mainly due to an increase in cardiac output) for both IGMA and EPMA. The results showed that vascular-dominant patterns were evoked during EPMA, while mixed (moderate increases in both cardiac output and total peripheral resistance) reaction patterns were evoked during IGMA. Post-task questionnaires confirmed that attention to an external stimulus was required much more in EPMA than in IGMA. These results indicate that the vascular-dominant reaction pattern was evoked in the state where attention to an external stimulus was heightened. The implications of the present findings are discussed in term of how to interpret the hemodynamic reaction patterns during mental stress.