Cortisol and yawning have been proposed as new potential biomarkers for the early detection of signs of neurological disease. Recent evidence from neuroscience has shown that there is communication between the motor cortex and more remote but vital centres such as the brain-stem and hypothalamus. Hormonal as well as neuronal links form the prosed network that influences and monitors the regulation of cortisol and the regulation of brain temperature governed by the hypothalamus. This evidence tends to support the prosed linkage between brain-stem, hypothalamus and motor cortex and lends support for the Thompson Cortisol Hypothesis which proposes threshold levels of cortisol elicit yawning for brain cooling, and parakinesia brachialis oscitans, the observed arm movement seen in brain-stem ischaemic stroke patients during involuntary yawning.
Simon BN Thompson