When food is scarce, a smaller brain will do

A new study explains how young brains are protected when nutrition is poor. The findings, published on March 7th in Cell Reports, a Cell Press publication, reveal a coping strategy for producing a fully functional, if smaller, brain. The discovery, which was made in larval flies, shows the brain as an incredibly adaptable organ and may have implications for understanding the developing human brain as well, the researchers say.

The key is a carefully timed developmental system that ultimately ensures neural diversity at the expense of neural numbers.

"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," said Cedric Maurange of Aix-Marseille Université in France. "This is a survival strategy permitting the developing to produce the minimal set of neurons necessary to be functional, at the minimum energetic cost."

Most of the neurons in the human brain are produced well before birth, as the grows and changes in the . But how the young brain copes with is an unresolved question. If a mother doesn't have enough food to eat, what happens to the brain of her baby?

To find out, Maurange and his colleagues looked to the fruit fly, a workhorse of biology. The much shorter lifespan of means that they reach the equivalent of toddlerhood in just four days' time.

Their developmental studies in the fly visual system reveal an early sensitivity to the availability of , ingredients that are the building blocks of proteins. They found that a fly with all the amino acids it needs ends up with a larger pool of neural stem cells than one lacking those nutrients. Later, when those start to produce the many different types of neurons, that nutrient sensitivity goes away. The end result is a brain that is functional but smaller. In some flies, the optic lobe contained 40 percent fewer neurons and still worked.

"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.

The findings may help to explain well-documented patterns of brain growth in humans. The is protected over other organs when nutrients are lacking late in fetal development, producing a brain that is large relative to organs such as the pancreas or intestine. But when nutrients are limited early in larval development, the brain remains small along with the rest of the body. Those growth patterns are known as asymmetric and symmetric intrauterine growth restriction (IUGR), respectively.

"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.

More information: Cell Reports, Lanet et al.: "Protection of neuronal diversity at the expense of neuronal numbers during nutrient restriction in the Drosophila visual system." dx.doi.org/10.1016/j.celrep.2013.02.006

Related Stories

The brain grows while the body starves

Aug 04, 2011

When developing babies are growth restricted in the womb, they are typically born with heads that are large relative to their bodies. The growing brain is protected at the expense of other, less critical organs. Now, researchers ...

Computer Technique Creates Map of a Fruit Fly Brain

Apr 12, 2010

Researchers, led by Hanchuan Peng, at the Janelia Farm Research Campus at the Howard Hughes Medical Institute in Ashburn, Virginia are working to map the fruit fly brain in a way that highlights how neurons ...

New human neurons from adult cells right there in the brain

Oct 04, 2012

Researchers have discovered a way to generate new human neurons from another type of adult cell found in our brains. The discovery, reported in the October 5th issue of Cell Stem Cell, a Cell Press publication, is one st ...

Recommended for you

Researchers unlock mystery of skin's sensory abilities

Dec 19, 2014

Humans' ability to detect the direction of movement of stimuli in their sensory world is critical to survival. Much of this stimuli detection comes from sight and sound, but little is known about how the ...

Tackling neurotransmission precision

Dec 18, 2014

Behind all motor, sensory and memory functions, calcium ions are in the brain, making those functions possible. Yet neuroscientists do not entirely understand how fast calcium ions reach their targets inside ...

User comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.