Parallel neural pathways control sodium consumption and taste valence. (https://pubmed.ncbi.nlm.nih.gov/37989313/)
These scientists wanted to understand how our brains perceive salt differently depending on how hungry or full we are. They discovered that when we have eaten enough food, high concentrations of salt make us feel like we don't want to eat it anymore. But when we haven't had enough salt, the same high concentrations actually make us want to eat it more.
To figure out why this happens, the scientists studied the different parts of the brain that control our feelings about salt. They used a special technique called transcriptomics state-to-cell-type mapping to see which genes were active in different parts of the brain. They also manipulated the activity of certain neurons in the brain to see how it affected our feelings about salt.
They found that there are specific circuits in the brain that control whether we find salt appetizing or aversive. One circuit, located in the hindbrain, makes us really want to eat salt when we haven't had enough. Another circuit, in the forebrain, helps us tolerate the taste of aversive salts when we have eaten enough.
The scientists also discovered that a certain type of neuron in the forebrain, called the lamina terminalis neuron, plays a big role in our tolerance for aversive salts. These neurons have a receptor called Ptger3, which helps them communicate with other cells using a molecule called prostaglandin E2 (PGE2). By manipulating the activity of these neurons, the scientists showed that they can change how sensitive we are to the taste of aversive salts.
Overall, this study reveals that our brains have different ways of perceiving and reacting to salt depending on whether we are hungry or full. These findings help us understand why we sometimes crave salt and why we might find it less appealing after a big meal.
Zhang Y., Pool AH., Wang T., Liu L., Kang E., Zhang B., Ding L., Frieda K., Palmiter R., Oka Y. Parallel neural pathways control sodium consumption and taste valence. Cell. 2023 Dec 21;186(26):5751-5765.e16. doi: 10.1016/j.cell.2023.10.020. Epub 2023 Nov 20.