The effects of stress in response to mirror drawing test trials on the electrogastrogram, heart rate and respiratory rate of human subjects

Electrogastrograms (EGGs), heart and respiratory rates were recorded simultaneously from human subjects and analyzed spectrally by the maximal entropy method. The stress of the mirror drawing test (MDT) significantly increased both the heart and respiratory rates with an associated increase in LF/HF ratios. MDT stress, however, increased (excited groups) or decreased (inhibited groups) the power amplitude and the power ratio, (peak power during MDT)/(peak power during rest), of the 1-cpm (0-2.4 cpm), 3-cpm (2.5-4.9), 6-cpm (5.0-7.4), 8-cpm (7.5-9.9) and 10-cpm (10.0-12.9) spectral group components of the EGG recording of the electrical activity of the gastrointestinal tract. The depression scores of the subjects in the MDT stress excited group were higher and their resting frequencies were significantly lower than those of the MDT stress inhibited groups in each of the epigastric, supra-umbilical and infra-umbilical 6-cpm frequency groups but not in the epigastric 1-cpm frequency group. Anxiety scores of the MDT stress excited groups were significantly higher and their power ratios were also significantly higher than those of the inhibited groups in each of the epigastric 10-cpm, the supra-umbilical 6-cpm and the infra-umbilical 1- and 3-cpm frequency groups. Therefore, depression scores appeared to have inhibitory effects on the resting EGG frequencies, while anxiety scores appeared to have facilitatory effects on the EGG power ratio during MDT stress. It is suggested that analysis of EGG under MDT stress would provide a measure of the stress sensitivity of the electrical activity of the human gastrointestinal tract.