Pictorial cognitive task resolution and expired minute ventilation, oxygen consumption, carbon dioxide production and heart rate.

Aims: To assess the impact of cognitive task solving on respiratory and cardiovascular parameters.

Methods: The ML870B80 Exercise Physiology System was used to record concurrently with EEG, the cardiorespiratory and metabolic functions of subjects during cognitive activity. The Expired Minute Ventilation (VE), Oxygen Consumption (VO2), Carbon Dioxide Production (VCO2) and Average Heart Rate (BPM) were ascertained for four periods: (1) rest or starting period, (2) reference period, (3) cognitive task solving period and (4) recovery period. Each period was defined by the type of presented visual stimuli and by the prearranged cognitive activity related to visual stimuli. The personality traits of participants were also determined.

Results: The momentary functional state of subject's brain (i.e. the period of the experiment) determined the average values of all measured parameters. During the cognitive task solving period the average VE, VO2 and VCO2 reached the lowest values while the HR behaved reversely--it was the highest in the cognitive task solving period. Further, the average VE, VCO2 and HR values but not VO2 value differed significantly from average values for the same variable measured in the rest period.

Conclusion: The changes in respiratory variables during the cognitive task solving period predicate the whole-body metabolic rate rather than the energy metabolism of the brain alone. However, the heart rate related to some personality traits of the subject has a tighter relation to brain's energy metabolic rate during the cognitive task solving--it affects the oxygen supply of the brain.