http://www.digitaljournal.com/science/can-our-metabolism-change-our-memory/article/431155

Can our metabolism change our memory?

Posted Apr 19, 2015 by Tim Sandle
Fruit flies learn and remember a preference for lower-calorie typical lab nutrition over high-calorie food, according to a new study.
A selection of cakes made for someone who requires a gluten free diet  from The savoy in London.
A selection of cakes made for someone who requires a gluten free diet, from The savoy in London.
The study suggests fruits flies (Drosophila) develop preferences for healthy foods that can be disrupted by overfeeding. This is the result of genes expressed in their brains. However, when the flies are faced with prolonged exposure to just the high-calorie option, their metabolic memories are lost.
With the study, the researchers wanted to probe the role of learning and memory in the brain’s maintenance of metabolic balance throughout the body. For this, the scientists trained Drosophila to associate particular smells with either normal food or a version with four times the amount of sorbitol, an artificial sweetener, which upped the calorie content. Fruit flies are commonly used in experiments. One reason is due to their short lifespan. This means that it is possible to evolve many generations of fruit flies in a relatively short time period. Using fruit flies as a model organism allows scientists to more rapidly unravel the complexity of biological patterns.
As the study progressed, the flies, to begin with, did not appear to prefer the smell linked to one type of food over the other. However, over time, the researchers found that the insects gravitated toward the odor associated with the normal food. This indicated the formation of what the researchers call “metabolic memories,” a remembered preference for the healthier option.
When the scientists exposed the flies to only high-calorie food for 12 days, however, the flies forgot their developed preference and were unable to distinguish between normal and high-calorie options. These flies not only exhibited high blood sugar and high lipid levels.
Whether the same effect applies to humans is not yet known, although it is an on-going area of discussion. If it does, having a form of metabolic learning and memory, through which the people are directed to balance food choice with caloric intake could have implications in the fight against obesity.
The study was carried out at the Albert Einstein College of Medicine in New York City. The findings have been published in the journal Nature Communications. The paper is titled "Metabolic learning and memory formation by the brain influence systemic metabolic homeostasis."