What happens when we pass out? Until recently, the scientific answer to such a question was: We are not quite sure what happens when we pass out. A new study has shed light on the answer to this mystery for the first time by identifying the genetic pathway between the brain and the heart that is responsible for fainting.
Fainting, or the scientific term for it, syncope, is a very common occurrence and about 40% of us experience it at least once in our lives. This may be a response to various situations such as overheating, seeing blood and needles, or even difficult bowel movements.
The common view among neuroscientists has been that During a fainting episode, the brain sends signals to the heart And the heart reacts based on these signals. The distinction of the recent study is that the researchers considered the heart as their sensory organ and hypothesized that this connection could happen both ways.
Augustine’s vignette“What we found is that the heart also sends signals to the brain that can change brain function,” says the study’s lead author and assistant professor at UC San Diego’s School of Life Sciences.
The research team turned to very old science to guide their research. In 1867, the Bezold-Jarich reflex (BJR), which was thought to be associated with fainting, was first described by researchers. It is associated with three classic symptoms that anyone who has ever fainted will likely recognize: a decrease in heart rate, respiratory rate, and blood pressure. Although scientists have known about BJR for more than 150 years, there was still much to learn about its underlying neural pathways.
Recent research was conducted on a special type of nerve cell called vagal sensory neurons (VSNs) in the heart. VSNs are part of clusters called ganglions, which are part of the vagus nerve.