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

#BrainBits 5: "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?"

September 11, 2015

Why We’re Obsessed with Pumpkin Spice Everything, According to Science

It was a humid, sticky 90 degrees when I made a quick trip to the grocery store in shorts and a tank top earlier this week. Despite the heat, however, the store clearly wanted me to think fall.

'Tis the season. ParentingPatch (Wikimedia Commons)
Weaving in and out of each aisle, I was inundated with row upon row of pumpkin spice M&Ms, pumpkin spice yogurt, pumpkin spice Oreos, pumpkin spice cereal, pumpkin spice beer, pumpkin spice cookies, pumpkin spice bagels, pumpkin spice Pop-Tarts, pumpkin spice popcorn, pumpkin spice hummus, pumpkin spice creamer for my pumpkin spice coffee…

At the risk of sounding any more like Forrest Gump's shrimp-obsessed friend Bubba, let’s just say that we’ve all gone a little mad. And with the official release of everyone’s favorite – the Starbucks Pumpkin Spice Latte – this past Tuesday, it’s time we ask: why are we so obsessed with pumpkin spice everything?

August 28, 2015

#BrainBits 4: "Why Do We Feel 'Pins and Needles' When our Appendages Fall Asleep?"

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.

Medical Treasure
Why do we feel "pins and needles"?  We've all experienced the strange sensation. Maybe it's when your alarm goes off in the morning and you realize you can't feel your arm to shut it off. Or when your legs are folded into a pretzel on the floor while playing Barbie with your kid and you can't stand back up. You give your dead appendages a shake, and suddenly you feel a surge of pins and needles. What causes that feeling?

There's actually a medical term for it  – paresthesia – defined as the tingling sensation caused by pressure or damage to peripheral nerves.

Don't pinch these! Gray's Anatomy
(Wikimedia Commons)
It occurs when there's prolonged pressure on a limb, like your arm positioned awkwardly under your head while sleeping or sitting cross-legged on the floor. The limb "falls asleep," either due to (1) arteries being compressed, thus blocking blood flow of oxygen and glucose to feed the nerves, or (2) directly pinching nerve pathways, causing normal neurotransmission to slow or cease.

Although your limbs may feel lifeless, your brain is receiving a signal of pain, saying "change your position already, idiot!" When you finally free your limb, the sensation of pain intensifies as blood returns to the area and nerves begin firing regularly. The "pins and needles" sensation occurs as certain areas nerve fibers receive blood nutrients and begin re-firing before others. Eventually, after a few seconds, equilibrium is established again.

A common misconception is that blood flow is blocked entirely to the affected limb when it "falls asleep." If that were true, we'd be experiencing a much more serious medical problem. Luckily, the 50,000-60,000 miles-worth of capillaries in our bodies ensure that our other tissues stay satiated and healthy. It would be as though a tourniquet were applied to a limb, and that's simply not what's happening.

Prolonged, regular compression to nerves can result in a more long-term sensation of "pins and needles," such as carpal tunnel syndrome. Consult a doctor if pain, tingling, and numbness is not relieved when you change body position.

Now, I'm going to undo my leg from under me (as I always do when I write) and go for a short walk to wake it back up. OUCH. Sometimes I never learn.

Stay tuned for next week's #BrainBits: "What the heck is déjà vu? Why do I get it and some people never do?"

August 12, 2015

#BrainBits 3: "Why Do I Get Hangry (Angry When Hungry)?"

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.

Niklas Hellerstedt (Flickr)
Why do we get hangry?  One lovely fall day a few years ago, my now-husband (I'm not sure why he married me after this) almost left me on the side of the road. We had just left a Penn State football game, and I was H-U-N-G-R-Y.

My resulting behavior was far from what you might consider "ladylike," much less "civilized." I won't even re-type the words that were spoken. Eventually, a pit stop for a burger and fries managed to tame my inner beast.

What causes the sensation of "hanger" – the phenomenon of feeling angry and short-tempered when hungry? Coincidentally, fellow The Conversation writer and obesity/nutrition researcher Dr. Amanda Salis recently covered this topic here. Do check out her article for details, as I'll be mostly summarizing below.

Basically, three major factors are thought to contribute to our bad tempers when we're famished:

Glucose metabolism. Mikael Häggström (Wikimedia Commons)
1. When we eat, carbohydrates are broken down into simple sugars, one of which is glucose. Right after a meal, the levels of glucose in our blood are high. Over time, though, blood-glucose levels drop. Eventually, if these levels fall far enough, your brain will perceive it as life-threatening. Unlike other organs, which have an energy back-up, your brain relies solely on glucose as a fuel source and requires a continuous supply. In fact, despite accounting for only 2% of your body's mass, your brain is estimated to use up 20-23% of your body's energy intake throughout the day, even at rest. Low blood glucose, obviously, signals, "imminent death! Act now!"

2. To our other organs, low glucose ramps up hormones that act to increase glucose in the body. Among these are epinephrine and cortisol, which are synthesized in the adrenal glands. These are both stress hormones, released when our body perceives threat, like a lion chasing us or an organic chemistry exam being handed out in class. That's enough to change someone's mood for the worse, right?

3. As it turns out, anger and hunger don't only share many of the same letters, but they're also controlled by similar genes. One of these genes produces a protein called neuropeptide Y, which not only stimulates eating behavior, but also regulates anger and aggression. Long story short, I probably had pretty high levels of neuropeptide Y after that football game.

What about you?
Do you get hangry, too?
Let us know
In this anonymous poll!

Stay tuned for next week's #BrainBits: "Why do we feel 'pins and needles' when our appendages fall asleep?"

July 29, 2015

When is the Best Time of Day to Keep a Diary?

For over 15 years now, I’ve faithfully kept a diary. Every night, from age 11 until my senior year of college, I snuggled into my bedsheets and rehashed the day’s events before nodding off to sleep. Even though I’m more likely to scribble down my thoughts just once or twice a week nowadays, I’ve found that writing in a diary before bed is a fun way to capture my memories – no matter how frivolous – to enjoy again years down the road.

Now a new study, published recently in The Quarterly Journal of Experimental Psychology, suggests that my nightly routine might help with something else: being able to recall a specific day’s events from memory weeks later.

Importantly, however, I may be at a greater advantage than some diarists because I typically write in my diary just before hitting the pillow, instead of waiting until the next morning.

Read more of my guest post with the British Psychological Society's Research Digest blog here.

July 15, 2015

#BrainBits 2: "Why Do I Remember Certain Things in Certain Places?"

This is the second post in my new #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.

Man Vyi (Wikimedia Commons)
Why do I only remember certain things in certain places? 
I'm glad you asked, because this happens to me all the time. I'll think about something, get off the couch and go to the kitchen to do whatever I told myself I needed to do, then completely lose my train of thought. Why did I come in here, anyway?

Funny enough, psychologists have actually studied this.

In a 2011 paper, Gabriel Radvansky and colleagues from the University of Notre Dame had participants play a computer game. In a virtual room, they were instructed to pick up an object from a table and take it to another table. The objects varied in color and shape. Importantly, as long as the participant was "carrying" the object, it was invisible to them.

Sometimes the participants' video game characters simply had to cross the room to put the object down. Other times, they had to walk through a virtual doorway to get to the table.

At random times throughout the experiment, participants were asked what object they were currently carrying. Interestingly, walking through a virtual doorway resulted in less accurate and slower responses than when they simply needed to cross a room.

But why? The authors suggest that we keep information in our working memory for as long as we consider it relevant. But when something related to the context of our memory changes — like the room we're in when we think about something — the memory must no longer be important enough for us to remember. Our brains probably think they're helping out by purging that memory for us. This is consistent with the hypothesis that, in general, recently-formed memories are extremely vulnerable to many interfering forces if they have not yet had a chance to consolidate.

To answer the broader question: we associate certain memories with certain places, and that's how we make sense of all the input flooding into our noggins. Our brains have incredible storage capacity, but they can only do so much. (Elephants* never forget, though.)

Do you forget more
When you walk through a door?
Let us know
In this anonymous poll!

Stay tuned for next week's #BrainBits: "Why do I get hangry (angry when I'm hungry)?"