SHENZHEN  -  When facing mounting tasks, will you continue to work or indulge in a cup of coffee? Behind this choice lies key brain activity that decides “what’s more important.”

Scientists have said they have located a part of the rat’s brain involved in this process of importance ranking, a discovery that will prompt the search for a similar mechanism in humans.

The study by a team of Chinese and American scientists was published in the prestigious journal Science on other day. First author Zhu Yingjie from Shenzhen Institutes of Advanced Technology of the Chinese Academy of Sciences said they found that a part of the rat’s brain called the paraventricular thalamus (PVT) was closely related to tracking the behavioral importance or “salience” of stimuli.

“What happens in your brain when you decide how to spend your evening, to work overtime or to drink a beer? Saliency detection is a key brain mechanism that facilitates learning and survival by enabling organisms to focus their limited attention on the most important event,” Zhu said.

He explained that neurons in PVT were robustly activated by salient stimuli. Through experiments, they found PVT was highly active when a thirsty rat found water, and would remain active even when the rodent was harassed by air puffers, suggesting its brain regarded water as a very important stimulus.PVT activity, however, fell to a low level when the rat faced heavier punishments like electric shocks, which prompted the animal to give up water to avoid pain. The salience of water, as illustrated by PVT activity, also dropped when the rat became sated after a drinking binge.

“PVT can dynamically track the salience of stimuli upon changes in internal homeostatic state and external environment,” Zhu told Xinhua. “Our initial prediction is that human brains have similar mechanisms.”