Fig. 7.

Proposed model of emetic stimulation of gastrointestinal (GI) vagal afferent fibers. A threshold is shown for the emetic reflex, for those animals with an emetic reflex (human, cat, dog, ferret, shrew, etc.) and pica in rodents (e.g., rat). This threshold triggers an immediate response to a potential threat (e.g., GI poison). Less immediate dangers (i.e., low concentraions of toxins) can trigger a delayed strategy that supports a conditioned taste aversion, which leads to avoidance of a toxin in the future.