Taste of time: A porous-medium model for human tongue surface with implications for early taste perception

Most sensory systems are remarkable in their temporal precision, reflected in such phrases as "a flash of light" or "a twig snap". Yet, the temporal response of human taste perception is complicated by the transport and diffusion processes of the stimuli through the papillae, saliva, taste pore, etc., to reach the taste receptors, processes that are poorly understood. In this study, we addressed this knowledge gap by modeling the transport and diffusion processes within the tongue surface through a novel micro-fiber porous medium approach and found that time-concentration profiles within the papilla zone rises with significant delay that well match experimental ratings of perceived taste intensity for both rapid stimuli pulses and longer sip-and-hold exposures. Diffusivity of taste stimuli, determined mostly by molecular size, correlates greatly with time and slope to reach peak intensity: smaller molecular size may lead to quicker taste perception. Our study demonstrates the novelty of modeling the human tongue as a porous material to drastically simplify computational approaches and that peripheral transport processes may significantly affect the temporal profile of taste perception.