New York, Sep 21 (IANS): Ever felt nauseous before an important presentation, or foggy after a big meal? It is because your gut is directly connected to your brain and is not linked to the hormones, say researchers who found that messages from the gut travel to the brain in milliseconds.

This indicates that conditions from appetite disorders and obesity to arthritis and depression may get their start in the gut, said researchers from the Duke University in North Carolina, US.

However, it was not clear how messages in this so-called "second brain" spread from our stomachs to our cerebrum.

For decades, researchers believed that hormones in the bloodstream were the indirect channel between the gut and the brain.

In the study, appearing in the journal Science, the researchers used a rabies virus jacked up with green fluorescence and traced a signal as it travelled from the intestines to the brainstem of mice.

They were shocked to find the signal cross a single synapse in under 100 milliseconds -- that's faster than the blink of an eye.

"Scientists talk about appetite in terms of minutes to hours. Here we are talking about seconds," said Diego Bohorquez, assistant professor at the varsity.

"That has profound implications for our understanding of appetite. Many of the appetite suppressants that have been developed target slow-acting hormones, not fast-acting synapses. And that's probably why most of them have failed," Bohorquez added.

Human brain takes in information from all five senses -- touch, sight, hearing, smell and taste -- through electrical signals, which travel along long nerve fibres that lie beneath your skin and muscle like fibre optic cables.

But, brain had a way of perceiving cues from the gut more quickly. Bohorquez noticed that the sensory cells lining the gut shared many of the same characteristics as their cousins on the tongue and in the nose.

"We think these findings are going to be the biological basis of a new sense," Bohorquez said.

"One that serves as the entry point for how the brain knows when the stomach is full of food and calories. It brings legitimacy to idea of the 'gut feeling' as a sixth sense."