University of California researchers identify slow-acting dopamine pathway

Researchers at the University of California, San Francisco, have identified a slow-acting dopamine pathway that explains how humans learn to crave certain foods, such as coffee, despite bitter initial tastes.

Published in the journal Nature, the study reveals that sensors in the digestive system detect nutrients like sugar and fat, sending signals from the gut to the brain. This process triggers a sustained release of dopamine in the basolateral amygdala, a brain region that helps the brain associate specific flavors with nutritional value.

In experiments involving mice, researchers bypassed taste by delivering nutrient-rich liquids directly into the stomach. They found that when this specific dopamine signal was blocked, the mice failed to learn which flavors contained calories. Conversely, when the dopamine fibers were artificially stimulated after consuming a calorie-free flavor, the animals developed a preference for that flavor. This mechanism allows the brain to update food preferences based on the physiological uplift provided by nutrients.