But there's also cannabinoid receptors in the liver.

There's a lot of CBD in that particular one as well, cannabidiol, another cannabinoid, a non-psychoactive cannabinoid, an important component to the medicine.

Because of this similarity, these new signals came to be known as cannabinoids.

What would you say the function is of these endo-cannabinoid chemicals?

Well, look at the amount of cannabinoid receptors in the brain - a lot of them.

By mapping out where cannabinoid receptors exist in the brain, and in what density, it should help shed light on the role of the cannabinoid system which scientists are only just beginning to understand.

It in fact takes longer for the siphon to close when they've been exposed to these cannabinoid compounds.

There, it met the cannabinoid receptor evolved so many millions of years earlier in the humble sea-squirt.

It targets only the cannabinoid receptors throughout the entire body and we're imaging the cannabis receptors in the brain.

But when the cannabinoid receptors are activated, they cause the nerve cells to reduce the amount of neurotransmitter they release.