**5. Olfaction and gustation**

Olfaction and gustation are our chemical senses and share a number of similarities and differences. Both senses extract information from the chemical stimuli in the environment, respond to a wide array of chemicals, and use G-protein-coupled receptors. However, in taste, this transduction mechanism is limited to sweet, bitter, and umami, whereas salty and sour use other signaling mechanisms. Receptor cells in olfaction and gustation show strong adaptation during continued stimulation and they undergo turnover and replacement throughout life. Both chemical senses provide important information for our survival and play a role in food selection and protect us from ingesting toxins. One difference between the two sensory systems is the fact that olfactory receptor cells are neurons and taste receptor cells are modified epithelial cells. Our understanding of the coding of taste qualities is better than that of odor quality. While olfactory stimuli evoke many sensations, no clear odor qualities have been described. The success of the perfume industry tells about the importance of olfactory stimuli as social cues.

## **Acknowledgements**

This work was supported in part by grants from the National Science Foundation (NSF IOS-1355034) to Thomas Heinbockel.
