What are the neural mechanisms behind taste and smell perception?

Taste and smell perception are mediated by specialised sensory cells in the taste buds and olfactory epithelium, respectively.

Taste perception, also known as gustation, begins when food or drink enters the mouth. The molecules interact with saliva and reach the taste buds, which are located on the tongue and other parts of the mouth. Each taste bud contains 50 to 100 specialised sensory cells, which are stimulated by different types of molecules. These cells have receptors that bind to the molecules and trigger an electrical signal. The signal is then transmitted to the brain via the gustatory nerves. The brain interprets these signals as different tastes: sweet, sour, salty, bitter, and umami (savory).

Smell perception, or olfaction, works in a similar way. When we breathe in, odour molecules enter the nose and reach the olfactory epithelium, a specialised tissue at the top of the nasal cavity. This tissue contains millions of olfactory neurons, each with one type of receptor that can bind to specific odour molecules. When an odour molecule binds to a receptor, it triggers an electrical signal. This signal is transmitted to the brain via the olfactory nerve. The brain then interprets these signals as different smells.

Interestingly, taste and smell are closely linked. The brain combines information from the gustatory and olfactory systems to create the perception of flavour. This is why food can taste bland when you have a cold and your sense of smell is impaired.

In addition, both taste and smell perception can be influenced by other factors. For example, the texture and temperature of food can affect how it tastes. Similarly, previous experiences and memories can influence how we perceive smells. This shows that taste and smell are not just simple sensory processes, but complex phenomena that involve multiple neural mechanisms and cognitive processes.