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A new study on larval flies reveals that when nutrition is poor, the brain protects itself by becoming smaller.

Scientists discovered that the body protects the brain by producing a smaller but fully functional brain when food is scarce.

Investigators said that the latest study on larval flies shows that the brain is an extremely adaptable organ and may even provide insight into the developing human brain.

The coping strategy works by staying on a carefully timed developmental system to ensure neural diversity at the expense of neural numbers, according to researchers.

"In essence, this study reveals an adaptive strategy allowing the reduction of the number of neurons produced in the face of sub-optimal nutritional conditions, while preserving their diversity," researcher Cedric Maurange of Aix-Marseille Université in France, said in a statement.

"This is a survival strategy permitting the developing brain to produce the minimal set of neurons necessary to be functional, at the minimum energetic cost," he added.

Most of the neurons in the human brain are produced when a baby is still in its mother's womb, and Maurange and his team wanted to understand how the fetus brain compensates when the mother doesn't have enough food to eat.

To answer this question, researchers looked to the fruit fly.  The study found that the development of the fly visual system has an early sensitivity to the availability of amino acids, ingredients that the building blocks of proteins. 

Researchers found that flies with all the amino acids it needs ends up with a larger pool of neural stem cells than flies lacking those nutrients.  Later, those neural stem cells start to produce a variety of different neurons when the nutrient sensitivity foes away.  Consequently, the brain of a fruit fly lacking all the necessary nutrients is functional but smaller. The study found that in some flies, the optic lobe still worked even though it contained 40 percent fewer neurons.

"We were surprised to realize that the optic lobe can have such a drastically reduced number of neurons under dietary restriction and yet remains functional," Maurange said.

Researchers said that the latest findings could help explain patterns of brain growth in humans.  The human brain is protected over other organs when nutrition is poor in late fetal development, producing a brain that is large relative to other organs like the pancreas or intestine.  However, when nutrients are limited early in larval development, the brain remains small along with the rest of the body.  Researchers explain that those growth patterns are known as asymmetric and symmetric intrauterine growth restriction IUGR

"Our work suggests new avenues to investigate how early nutrient restriction affects mammalian brain development and may help in understanding the mechanisms underlying symmetric and asymmetric IUGR in humans," Maurange said.