A few days before moving on campus my sister and I attempted to make bread for the first time and it went much better than either of us expected. After spending half the day making the dough, proofing it, kneading it, proofing it again, and finally baking it, the satisfaction we felt while consuming the fruits of our labor, i.e the milk break, at around one in the morning was an experience like no other. When I think back to this moment, it reminds me of how impactful our sense of taste is for our emotions. For many of us, there are so many wonderful memories that revolve around food, like going out to dinner with friends, having home cooked meals with family, or simply enjoying the flavors of good food. This realization then spiked my interest into how our brain takes these foods that we consume and converts them into a variety of flavors and sensations that we can ultimately taste.

It’s common knowledge that there are five major taste sensations: sweet, sour, salty, bitter, and umami, which is described as savory. These five taste sensations are what our tongue tries to determine and differentiate before relaying these taste messages to the brain’s gustatory complex. The way these different taste sensations are determined is through the use of our taste receptor cells that are clustered into taste buds. Each cluster of taste buds is composed of thousands of receptor cells that relay information about the certain taste to the brain. Once food or drinks are consumed the chemical travels down the microvilli of the clusters of taste receptors cells where the chemical binds to them.  Sweet, umami, and bitter chemicals only require receptors to relay information, but salt and sour chemicals need to pass through an ion channel before being binded to the receptor. Once this binding of the chemical to the receptor occurs a series of reactions, called depolarization, creates an action potential which is a large amount of electrical activity that helps transmit this taste signal to the brain (Bowen 2008). A unique characteristic about taste signals is that once that initial chemical stimulus occurs, there is a rapid reset of the taste nerves that help communicate this signal to the brain, which is what causes the very strong initial flavor of the food that ends up fading quickly (Bowen 2008). 

The next major process once the taste signal is transmitted to the brain is how the brain interprets the taste signal. Once the taste signal reaches the brain, more specifically the brain stem and gustatory cortex, the pathways divide and the taste signals either are transferred to the limbic system or the cerebral cortex. The limbic system is composed of the hypothalamus, the amygdala, the thalamus, and the hippocampus which are major contributors to emotional response and memory formation. The cerebral cortex functions to identify messages and form thoughts. When these work together in regards to taste signals, the limbic system interprets the signals and determines whether we experience a enjoyable, awful, nostalgic, or mediocre reaction that might remains in our memories, and the cerebral cortex can help form opinions or thoughts on the taste and determine whether it is worth eating or not (Murray 2010). 

In a research experiment done by Yuiqing Peng and co. at Columbia University, mice were used to analyze if each taste has a distinct cortical field in the brain, basically wondering if the different tastes have their own section of the cerebral cortex where they’re interpreted. They determined the location of the sweet and bitter sections/corticals in the brain of the mice and activated those areas with injections. As a result, the “observations demonstrate that neurons in the sweet and bitter cortical fields drive attractive and aversive responses, respectively” (Peng Y 2015). This experiment essentially confirms the connection of the taste receptor cells in the tongue to the limbic system and cerebral cortex of the brain, since the mice who had the sweet cortical activated showed behavioral attraction while the mice with the bitter cortical activated had behavioral avoidance (Peng Y 2015).

It is so fascinating to learn about how complex our senses are, not only taste, but sight, smell, touch, and hearing as well. They each use completely different neurological pathways to the brain, different parts of the brain, and have completely different functions, but still manage to be so intertwined with each other. For example, our perception of taste can be easily influenced by smell as well. To connect back to the milk bread my sister and I made a few weeks ago, it is interesting to now know how these amazing memories are being made just from the simple foods we eat!

Bowen, Richard. “Vivo Pathophysiology .” Physiology of Taste, Colorado State, 2008. www.vivo.colostate.edu/hbooks/pathphys/digestion/pregastric/taste.html.

Murray, Marjorie A. “Our Chemical Senses: 2. Taste.” Experiment: How Taste and Smell Work Together, 2010. faculty.washington.edu/chudler/taste.html.

Peng Y, Gillis-Smith S, Jin H, Tränkner D, Ryba NJ, Zuker CS. Sweet and bitter taste in the brain of awake behaving animals. Nature. 2015 Nov 26;527(7579):512-5. doi: 10.1038/nature15763. Epub 2015 Nov 18. PMID: 26580015; PMCID: PMC4712381.