Ever wonder why a food you love suddenly doesn't taste the same? Why you lose your appetite for things you once craved?

Well, scientists studying the brain's reaction to pleasing tastes have discovered possible reasons for your bored taste buds. It all hinges on an area of the brain called the ventral pallidum, a part of the limbic system of the brain that controls motor-muscle functions and our sense of pleasure or reward.

Researchers at the University of Michigan, who conducted laboratory studies on rats, found that neurons in the ventral pallidum fire more frequently when pleasurable sensations are experienced. However, if medications or other factors interfere with the firings, the neuron activity is limited, a signal of responses to displeasure. There is, in effect, a kind of Morse code for registering pleasurable tastes.

There may be a number of reasons why human taste preferences suddenly change. Drug use (prescription, nonprescription or illicit) can alter the chemical balance in the brain and interfere with the transfer of taste sensations. If neurons in the ventral pallidum misfire, for example, it could trigger eating disorders such as anorexia or bulimia. Smokers often experience altered taste as a result of nicotine. And people who suffer from depression often report feeling uninterest in food -- likely because their taste pleasure response has been thrown off balance.

You may also notice a sudden difference if you've changed your diet. Say your doctor started you on a low-salt diet. When strong-tasting elements such as salt are removed from the diet, food often tastes bland. This is because the brain adjusts to the intensity of flavors. When one flavor is taken out of the diet, the brain takes time to readjust. The length of this adjustment period may vary depending on age and the intensity of the particular taste element.