A revolutionary Georgia State University study uncovered surprising new information about how salty foods affect the brain. The research focused on the relationship between neuron activity and blood flow deep within the brain.
When neurons become activated, blood flow increases rapidly to the area. Known as neurovascular coupling, or functional hyperemia, this process occurs when blood vessels called arterioles dilate. Neurovascular coupling forms the foundation of functional magnetic resource imaging (fMRI). Experts rely on this concept to diagnose brain disorders, looking for restricted or weak blood flow areas.
Prior studies on neurovascular coupling have only focused on superficial brain areas, such as the cerebral cortex. Scientists primarily analyzed how sensory stimuli, such as visual or auditory, affected blood flow.
However, scientists knew very little about whether these processes occurred the same way in deeper parts of the brain before this study. These brain regions process stimuli produced by the body, known as interoceptive signals.
A team of scientists collaborated on the study to examine these processes in deep areas of the brain. Dr. Javier Stern, professor of neuroscience at Georgia State and director of the university’s Center for Neuroinflammation and Cardiometabolic Diseases, led the study. The scientist team developed a new approach that combines surgical methods and advanced neuroimaging.
The team’s research focused on the relationship between salty foods and the hypothalamus, an area deep within the brain responsible for critical bodily functions. These include drinking, eating, reproduction, and regulating body temperature.
The study, published in the journal Cell Reports, examined how salty foods affected blood flow to the hypothalamus.
Researchers Explain the Link Between Eating Salty Foods and Brain Health
“We chose salt because the body needs to control sodium levels very precisely. We even have specific cells that detect how much salt is in your blood,” said Stern. “When you ingest salty food, the brain senses it and activates a series of compensatory mechanisms to bring sodium levels back down.”
The body accomplishes this partially by activating neurons which result in the release of vasopressin. In fact, this antidiuretic hormone plays a critical role in maintaining the right amount of salt in the body.
Previous studies on how salty foods impact the brain discovered a positive association between neuron activity and increased blood flow. However, researchers observed the opposite in this study: blood flow decreased when neurons in the hypothalamus became activated.
Stern said this:
“The findings took us by surprise because we saw vasoconstriction, which is the opposite of what most people described in the cortex in response to a sensory stimulus. Reduced blood flow is normally observed in the cortex in the case of diseases like Alzheimer’s or after a stroke or ischemia.”
The team called this phenomenon “inverse neurovascular coupling,” or hypoxia due to blood flow slowing down. They also found other interesting differences in the study about salty foods affecting the brain compared to previous findings. Blood vessel dilation in the cortex occurs in a highly localized, rapid fashion. However, in the hypothalamus, the response occurred in a dispersed, slow manner over some time.
“When we eat a lot of salt, our sodium levels stay elevated for a long time,” said Stern. “We believe the hypoxia is a mechanism that strengthens the neurons’ ability to respond to the sustained salt stimulation, allowing them to remain active for a prolonged period.”