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October 29, 2015

What are Hiccups?

This is the final post in my #BrainBits series. Although this series has ended, you are always welcome to e-mail me or tweet me suggestions for neuroscience-related topics that you've always wondered or want to learn more about. I just might write about them on the blog!

What are hiccups?  Possibly the most annoying thing (in my opinion, anyway) that can happen to the body on a semi-regular basis is HICCUPS. They're unexpected, they're rhythmic, and they're darn hard to get rid of.

But what are they in the first place, anyway?

Hiccups can also be...terrifying? (Watch the kitten on the right.)
Pretty nice image to tie in National Cat Day (today), Halloween (Saturday), and the topic of this post, eh? Reddit (anfea2004)

When we breathe normally, air is drawn into the lungs thanks to the contraction of the diaphragm, a sheet of muscle that extends just under the lungs. This contraction is controlled by the firing of the phrenic nerve.

With hiccups, the phrenic nerve becomes irritated, resulting in erratic, involuntary contractions of the diaphragm. The spasm is so strong that it causes us to draw in a quick breath and our vocal cords to close briefly, resulting in the characteristic (read: embarrassing) "HIC!" sound.

Mayo Foundation for Medical Education and Research
So what causes this phrenic nerve irritation? Most commonly, gastric distention caused by bloating, eating too quickly or eating too much, carbonated beverages, swallowing excessive air (like when chewing gum), and even spicy food can tickle the nerve, sending the diaphragm into spontaneous contractions. Rapid changes in temperature (like eating hot food with a cold drink), sudden excitement, or stress can also affect this reflex. People with central nervous system disorders or tumors that affect the phrenic nerve can suffer from intractable hiccups that may require medical attention.

What's the best way to treat hiccups? For more persistent hiccups, medication is available to calm the phrenic nerve, though no single drug has been proven particularly effective.

For your everyday, run-of-the-mill hiccups, grandma's remedies are best. Increasing the partial pressure (volume per area) of carbon dioxide — like holding your breath or breathing into a paper bag — stops hiccups for many people, though the mechanism isn't entirely clear. Some people find success in stimulating another nearby nerve, the vagus nerve, by eating dry bread, a spoonful of peanut butter, or other foods that are a bit harder to swallow.

For me, personally, the most effective treatment is swallowing 10 gulps of water while holding my nose — it's probably a combination of increased carbon dioxide and vagus nerve stimulation that does the trick. (It feels weird, but works like a charm every time.)

The World Record for longest hiccups is held by Charles Osborne. The hiccups began in 1922 just as Osborne went to weigh a hog before slaughtering it. “I was hanging a 350 pound hog for butchering.  I picked it up and then I fell down.  I felt nothing, but the doctor said later that I busted a blood vessel the size of a pin in my brain.”

It's thought that this burst vessel affected an area of the brain that helped inhibit hiccups. Unable to find a cure for 68 years, they finally ceased on their own in 1990. He died just a year later. It's estimated that he experienced 430 million hiccups during this time.

How do you cure your hiccups? Let me know in the comments!

October 6, 2015

How Much Can You Really Learn While You're Asleep?

In Aldous Huxley’s 1932 novel Brave New World, Polish boy Reuben Rabinovitch falls asleep next to a radio receiver. When he wakes up, he is able to recite the entire broadcast. He has no idea what any of it means, though – it’s all in English.

Maria Zarnayova/EPA
Countless articles today claim that you can actually learn music, hone your foreign language skills, or cram for tomorrow’s math exam during sleep. And there is a whole industry trading on this idea. Subliminal message tapes, popularized by self-help guru Tony Robbins, promise to help you stop smoking, lose weight, and even brush up your golf skills and find love – all the while catching some shut eye.

The big sell of “sleep learning” is seductive – how lovely it would be to be productive while we lie like lifeless lumps in bed. But is it actually based on any evidence?

Read the rest at The Guardian here.

October 1, 2015

What the Heck is Déjà Vu? Why Do I Get It and Some People Never Do?

This is the latest post in my #BrainBits series, where I'll answer your burning neuroscience questions in 60 seconds or less. If you have a question you'd like me to answer, you can e-mail me, tweet me, or submit your questions anonymously here.

Erika Wittlieb (Pixabay)
What is déjà vu?  Many of us know the feeling. You'll be going about your day, minding your own business, folding some laundry...nothing out of the ordinary. Suddenly a sensation of familiarity washes over you, and you're completely aware that it's happening. I've been here before. Except you haven't. Or have I? You might try to think back and pinpoint when you'd experienced this moment before. But just as quickly as the feeling hits you, it's gone again.

Did you predict the future? Were you seeing something from a past life? What the heck is déjà vu, anyway?

Perhaps unsurprisingly, déjà vu (French for "already seen") is, scientifically, pretty poorly understood. There are a few theories, however:

University of Bristol
  • Déjà vu may be the result of some sort of "mismatch" in how we're simultaneously sensing and perceiving the world around us. Perhaps we smell something familiar, for example, and our mind is instantly transported to the first time we smelled it. (It's a vague theory, though, and doesn't explain why most déjà vu episodes don't reflect true past events.)
  • Déjà vu may be a fleeting malfunctioning between the long- and short-term circuits in the brain. The information our brain takes in about its surroundings may "shortcut" its way straight to long-term memory, bypassing typical storage transfer mechanisms. When we have a moment of déjà vu, it feels as though we're experiencing something from our distant past. 
  • A region of the brain called the rhinal cortex, involved in detecting familiarity, may be inexplicably activated without actually activating memory (hippocampal) circuits. That may explain why déjà vu episodes feel so non-specific when we try to figure out where and when we had previously experienced a particular moment. In fact, some patients with epilepsy reliably experience déjà vu at the beginning of a seizure. For these individuals, experimental stimulation of the rhinal cortex — and not so much the hippocampus itself — induces déjà vu.

Déjà vu is estimated to occur in 60-70% of people, and most commonly in those between the ages of 15 and 25 years. (Why? No idea.) Interestingly, I had previously written about déjà vu years ago out of my own curiosity on the matter, having experienced it fairly frequently. I'm now 26, though, and can't remember the last time I had an episode.

Are any of these theories correct? We may never know. After all, an episode of déjà vu is completely unexpected and, for most of us, extremely rare. Empirical research on the topic is next to impossible.

The most parsimonious explanation, then, is likely the following:


What about you?
Do you experience déjà vu?
Let us know
In this anonymous poll!

Stay tuned for the next #BrainBits: "What are hiccups?"