Studying is said to be difficult on a full stomach but German scientists recently found that hunger doesn't help us learn either, local media reported Thursday.

In nature, a high level of cognitive skills is required when animals search for, stockpile, protect and consume food. The cognitive process is influenced by numerous hormones, including ghrelin, a peptide hormone responsible for hunger.

It has been proven that ghrelin can improve the intellectual power of rodents, especially in spatial learning. Only little, however, has been known about whether and how ghrelin influences cognitive performances of mankind.

To study the effects of ghrelin on human beings, scientists from German Planck Institute of Psychiatry arranged an experiment, asking 21 healthy men to take a virtual walk with a modified free computer game software.

While the participants walked in the digital suburb, their brain activities would be recorded in real time by a magnetic resonance imaging scanner.

By walking, they were also asked to memorize certain words in two rounds, when ghrelin and placebo were used in turn. A double-blind method was applied, which means except some experiment operators, neither the participants nor the scientists knew in which round ghrelin had been used.

The participants were asked which words they had remembered the next day. The result shows that no difference has been seen between the effects of ghrelin and placebo.
The study result has already been published in the US journal NeuroImage.