The Tongue as an Excitable Medium

(GT) is a benign condition affecting approximately 2% of the population 1 , whereby the papillae covering the upper part of the tongue are lost due to a slowly expanding inflammation. The resultant dynamical appearance of the tongue has striking similarities with well known phenomena observed in excitable media, such as forest fires automata simulations. We emphasize similarities with other excitable systems as well as unique features observed in GT. Our results shed light on the evolution of the inflammation and contribute to the classification of the severity of the condition, based on the characteristic patterns observed in GT patients. Some of the most important organs in the human body incorporate microscopic coupled elements possessing a property of excitability. The resultant network usually performs a specific function, crucial for the successful operation of the organ. Under certain conditions, however, this excitable medium can experience unwanted and in some instances harmful dynamics. Probably the most well known example is the heart muscle, which under normal conditions contracts periodically due to the propagation of electrical waves resulting in blood being pumped to the different parts of the body. Irregular heart rhythm (cardiac arrhythmias) caused either by abnormal initiation of impulses 13 or due to the occurrence of spiral waves 11,12 may be life-threatening. Yet another example is the cerebral cortex, which under normal conditions is responsible for important functions such as conciseness and memory, but may experience dangerous electrophysiological waves (i.e., spreading depression waves 19,20). The human tongue is vital for tasting, mastication and speech. With respect to the former function, a thin layer (epithelium) consisting of four types of tiny papillae