Asghar Hussain, Sikandar Ali Sheikh.
Effect of Mental Stimulation on face immersion in man.
Pak Armed Forces Med J Jan ;49(1):21-3.

The aim of the study was to assess influence of higher centres, through mental stimulation, on diving response, with breath holding face in condition, as determined by heart rate. 15 healthy subjects, at ages 18 to 35 years, were studied. The R-R interval of the ECG variable for 30 seconds was recorded with breath hold face out and face in conditions with reading and doing mental arithmetic. Face immersion with reading has no significant effect on heart rate, while mental arithmetic increased the heart rate significantly in both face out and face in conditions. This indicated that mental arithmetic modify the neural reflex at central level probably through inhibiting vagal activity or stimulation of sympathetic innervation.

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