Now, a new University of Michigan study gives new evidence about what's going on in the brain when we taste something we like, or develop a liking for something we once hated.
And although the study used rats instead of people, it has direct implications for understanding the way we perceive pleasure ?and the reasons why some people develop problems, such as drug abuse, depression or anorexia, that knock their pleasure response off balance.
In a new paper in the November issue of the Journal of Neurophysiology, U-M neuroscientists and psychologists report the findings from direct monitoring of an area of the brain known as the ventral pallidum. Located deep in the brain, it's a kind of traffic center for signals from different areas of the brain that process tastes and pleasurable sensations.
The researchers were able to track the activity of brain cells in that area while the rats received water, salt water and sugar water directly into their mouths. They also recorded how the rats behaved while they tasted those different solutions, including signs that they liked or disliked the tastes. And, they repeated the tests when the rats had been treated with drugs that greatly reduced their bodies' salt levels.
At first, the rats all behaved negatively after tasting a strong salt-water solution, compared to the water or sugar water. Their ventral pallidum brain activity was also much lower in response to the salt water.
But when the researchers put the rats into a salt-deprived state using a combination of diet and hormones that cause the body to get rid of salt, the picture changed. Suddenly, the rats' brain activity rose as high when they received the salt water as it had when they received sugar water. The effect lasted for a while af
Source:University of Michigan Health System