There are so many types of communication that occur in our world, some of which you’ve probably never even considered. Having a chat over coffee, fungal networks sending each other signals underground, or even plant-to-farmer communication, there are so many types of relationships that rely on the conveyance of messages.
It’s interesting to think about how the brain communicates with our body in this way. Tiny tweaks from internal and external stimuli can trigger changes in how we function. For example, when it’s cold and our body temperature starts to drop, our brain cleverly acts like a conductor, triggering our muscles to shiver and our hairs to rise and warm us up. This ability for the body to sense changes within itself is called interoception, and it is key for survival.
The vagus nerve: the link between our brain and organs
The main player in the transmission process from the brain to the body is the vagus nerve. This is the nerve that sends information about internal organs’ function to the brain and acts on them accordingly.
Researchers from Yale School of Medicine have discovered something completely new about how the nerve transmits signals. There are three key features to the nerve action that are acted on by vagal sensory neurons in the brain. These include where the organ signal is coming from, which layer of tissue it’s coming from, and what the stimulus is.
Having these multilayered steps allows for a high precision of action to be carried out. “This is the first time we actually know how different body signals are being represented through the vagal interoception system to the brain in a very precise and accurate manner,” says Rui Chang, senior co-author of the study published in Nature.
How does the vagus nerve act so specifically?
The team uncovered that the vagus nerve was able to differentiate between signals due to genetically encoded sequences. This works kind of like a barcode, each organ or tissue layer having a unique serial number that the nerve relays to the brain to give a highly specific finding. “By knowing these two codes, you know precisely where a particular neuron in the vagus nerve projects in the body,” added Chang.
Specific types of neurons have the same code
Through the creation of a new technique that used calcium to track nerve signals, the team was also able to figure out that different sets of neurons have different specific functions. For example, detecting an organ stretching or nutrient balance, which are encoded to them genetically. “For neurons that are designed to detect stretch, for example, it doesn’t matter where the stretch happened—it could be from the lung, stomach, or small intestine. In other words, neurons with the same ‘stretch’ code respond to stretches regardless of organs or tissue layers,” explained Chang.
Why is this important?
Vagus nerve stimulation has been shown to be effective in treating epilepsy and depression, although scientists don’t quite know why. Through a deeper understanding of the multilayered interoceptive capabilities of the vagus nerve, more advanced and successful treatments could be invented for all sorts of organ-based disorders.
Source study: Nature – A multidimensional coding architecture of the vagal interoceptive system