Tytus Sosnowski

Mental task demands and cardiovascular response patterns.

Though it is well known that solving mental tasks elicits tonic increases in cardiovascular activity, a good theory explaining the specificity of this effect is lacking. It is also unclear why different kinds of mental tasks elicit different response patterns. The aim of the experiment was to compare cardiovascular response patterns during three tasks matched for their duration (8 min) and probability of success (.5): a simple RT task and two numeral tasks. One of them (a RUN task) involved program running (performing basic arithmetical operations), the other (an EDIT task) required searching for a problem solution. Seven cardiovascular variables, measured by a Portapres monitor, were analyzed. The analysis showed, among other findings, that the tonic increase in blood pressure and heart rate was greater during the RUN task than during the RT task. On the other hand, the EDIT task and the RT task produced almost identical response patterns.

Program running versus problem solving: two patterns of cardiac response.

Our previous research showed that mental tasks that involve program running (RUN tasks), e.g. performing arithmetic operations, cause greater tonic increase in cardiovascular activity than tasks that require a search for problem solutions (EDIT tasks), e.g. logical completion of a series of digits. However, it was not clear what physiological mechanism was responsible for this difference. The aim of the experiment was to compare cardiac response patterns while solving three mental tasks matched for their duration and level of difficulty: a simple RT task (control task) and two numerical tasks: RUN and EDIT. Forty-eight males, university students, divided randomly into three groups (n=16), participated in the experiment. Each group performed a different task. Task-evoked changes in heart rate (HR), strong volume (SV), cardiac output (CO), pre-ejection period (PEP), and power of HF component of heart rate variability were subject of the analysis. The results showed a higher tonic HR increase during the RUN task than the two other tasks and larger shortening of PEP during the RUN than the EDIT task. The HF power was larger during the RT task than the RUN task. No significant between-task difference was found in SV and CO changes. The results seem to support the hypothesis that higher cardiac responsiveness to RUN than EDIT tasks is mainly due to the difference in sympathetic activation.

RUN/EDIT information processing mode and phasic cardiac acceleration

Our previous research showed that tasks demanding running of ready-to-use programs (RUN tasks) caused a greater tonic heart rate increase than did tasks that require problem solving (EDIT tasks). We found also a similar though not so consistent effect in the analysis of phasic cardiac acceleration. The aim of the present study was to replicate the last finding using new experimental tasks. Fifty-four male secondary school pupils were divided randomly into three experimental groups. Each group performed a different version of a nonsignaled reaction time (RT) task: simple RT, sensory choice RT, and semantic choice RT. Participants had to respond within an established time limit, but this limit was continuously modified in such a way that each participant was given positive feedback in approximately 50% of trials. According to expectations, the simple RT task evoked greater phasic cardiac acceleration than did the choice RT tasks.

Sources of uncertainty and psychophysiological state changes under conditions of noxious stimulus anticipation

The main aim of the experiment was to compare the effect of the two variables (regarded here as different sources of subjective uncertainty) - probability of stimulus occurrence and ambiguity of the message about this probability - upon changes in heart rate (HR) and skin resistance (SR) during anticipation of a noxious stimulus. Three other independent variables - the type of stimulus (shock vs. sound), repetition of trials (two series of trials), and time-within-trial - were controlled as well. Results indicate that ambiguity as compared to probability has a more pronounced effect upon SR changes. Effects of the two variables upon HR changes are not significant. Moreover, in the shock group, the effect of repetition of trials was found to have a habituation effect for HR changes and a dishabituation effect for SR changes.

Patterns of brain and cardiovascular activation while solving rule-discovery and rule-application numeric tasks

It is known that solving mental tasks leads to tonic increase in cardiovascular activity. Our previous research showed that tasks involving rule application (RA) caused greater tonic increase in cardiovascular activity than tasks requiring rule discovery (RD). However, it is not clear what brain mechanisms are responsible for this difference. The aim of two experimental studies was to compare the patterns of brain and cardiovascular activity while both RD and the RA numeric tasks were being solved. The fMRI study revealed greater brain activation while solving RD tasks than while solving RA tasks. In particular, RD tasks evoked greater activation of the left inferior frontal gyrus and selected areas in the parietal, and temporal cortices, including the precuneus, supramarginal gyrus, angular gyrus, inferior parietal lobule, and the superior temporal gyrus, and the cingulate cortex. In addition, RA tasks caused larger increases in HR than RD tasks. The second study, carried out in a cardiovascular laboratory, showed greater increases in heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) while solving RA tasks than while solving RD tasks. The results support the hypothesis that RD and RA tasks involve different modes of information processing, but the neuronal mechanism responsible for the observed greater cardiovascular response to RA tasks than to RD tasks is not completely clear.