What causes brain freeze?

Chris put this question to Aimee Eckert from the University of Sussex...

Aimee - Oh yes, brain freeze - I know that well. So, when you’re eating a delicious ice cream, or drinking something really cold, you are rapidly changing the temperature of the blood vessels that are close to the surface of your skin in your mouth; because the blood's really near the surface of the skin and it responds to temperature really quickly, which is why we take people’s temperatures under the tongue. When you change temperature in some areas of the blood, the blood is on its way to the brain; the brain doesn’t have pain receptors as such, but the outer covering of the brain does...

Chris - The meninges?

Aimee - That’s right. You’ve been doing your homework Chris. So when this cold blood reaches the arteries at the entrance to the brain, the arteries don't like it and they start contracting and dilating and the nerves around the arteries pick this up and our body interprets that as pain. It’s a bit of protective mechanism to say "stop, don’t do this!" We’re a human body and we don’t like sudden changes in temperature.

Chris - Super. So basically, I put something cold in my mouth. I cool down my mouth, which interprets the localised cooling as a "oh, my head must be too cold?"

Aimee - Yes, exactly.

Chris - And that causes a rebound opening up of these arteries supplying my brain, because it thinks my brain is now too cold and needs more hot blood. And that dilatation of the arteries is painful and I get that headache for a bit?

Aimee - Yeah.

Chris - Well now I feel much better for that! And there’s nothing I can do about it?

Aimee - Nothing you can do about it except cool it with the ice cream! But, if it makes you feel any better, this phenomenon’s also been reported in pets. So cats and dogs also get brain freeze.

Chris - How do they know that?

Aimee - Umm. Have you been on YouTube recently?

克里斯-人actually said “what would be the hardest thing you would have to explain about the modern world to someone who was from 50 years ago who saw how we lived?” And the person said “well, I think the hardest thing to explain is how we have access to this amazing thing called the Internet, which has all of the information that mankind has ever generated on it, and we use it 90 per cent of the time to share pictures of cats and kittens!”

Aimee - Well, yeah!

Chris - So, go on, explain how do we know that a cat and a dog has brain freeze then? I’m intrigued!

Aimee - Maybe it’s my bias from viewing this entertainingly adorable cat video.

Chris - So, let me just get this straight. This is a scientific study done by you looking at YouTube videos of cats and dogs. So you’re saying it’s shaky evidence, but there might be some evidence that animals could experience this phenomenon?

Aimee - Yes.