Neuroscience: Flies count calories

Flies can remember the caloric content of food and learn to prefer food with normal caloric content, reports a paper in Nature Communications. The research indicates that this preference is lost after forced consumption of a high-caloric diet.

Learning and memory formation are fundamental processes for survival under changing environmental conditions. Whether metabolic memory (the memory of caloric information about ingested food) is involved in maintaining metabolic homeostasis has not been determined.

Dongsheng Cai and colleagues identify multiple genes and a number of brain regions, in Drosophila flies, thought to be involved in the learning and memory of metabolic information. They find that this metabolic memory is easily disrupted by genetic changes or chronic over-feeding, which leads to increased calorie intake and flies with diabetes-like symptoms. They also find that metabolic memory can be improved, and over-eating prevented, by blocking a genetic pathway in the brain.

Preliminary studies performed by the authors also suggest that mice may exhibit a similar type of metabolic learning and memory, potentially in the hypothalamus. They hope that this research represents a step towards understanding the factors that regulate body weight in mammals.