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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?

Thinkstock
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.

MetroParent
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)?"


July 8, 2015

The Psychology of Jimmy Kimmel’s “Lie Witness News”

ABC/Jimmy Kimmel Live
If you’re not familiar with Jimmy Kimmel Live’s segment “Lie Witness News,” you’re missing out on a pretty fascinating (and pretty hilarious) psychology experiment.

The premise is this: Kimmel’s staff takes to the streets of L.A. as roving reporters, questioning pedestrians about recent stories in the news. These stories, however, are…not quite right, to say the least.

Take last Friday’s Independence Day-themed “Lie Witness News” (you can see the whole video at the end of the post) where a “reporter” asks a man if he’d be watching “President Obama’s planned 4th of July confederate flag burning with the last surviving Tuskegee Airman and the Wu Tang Clan.”

“I will,” the man replies with a straight face.
“Have you heard about that?”
“I have.”
“Are you excited for it?”
He replies, “A little.”

The reactions of the interviewees are fascinating. Without flinching, they always have an opinion on the matter, and apparently — somehow — they’ve always heard the story from another source beforehand.

But why aren’t people thinking twice about these ridiculous questions? Why does this segment work so well?

#BrainBits 1: "Why Does Coffee Make Me Poop?"

This is the first 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.

Free Stock Photos
Why does coffee make me poop?  Come on, fess up. It happens to the best of us. In fact, I just finished my morning mug, and...anyway, you get the picture.

If a cup of joe makes you go, you're not alone – 29% of people have the "desire to defecate" after drinking coffee, according to this 1990 paper published in the journal Gut. In addition to the survey, the study authors studied bowel motility in 14 subjects before and after drinking caffeinated coffee, decaffeinated coffee, or hot water using a manometry probe (fun!).

Common sense suggests that, like its stimulating effects on the brain, caffeine must also act on the muscles of the colon, resulting in peristalsis (coordinated contraction/relaxation of the GI tract that cause bowel movements). But the results suggested something else.
Peristalsis. Adrignola (Wikimedia Commons)
When asked, 6 subjects who drink coffee and 4 who drank decaf said they felt they could defecate afterward, compared to no subjects who had hot water.

Eight of the 14 subjects who had claimed that coffee typically induces the urge to purge showed increased bowel activity within four minutes of drinking coffee. This continued for at least 30 minutes. But interestingly, a similar increase was seen in those who drank decaf, suggesting that a compound in coffee other than caffeine may be responsible.

Interestingly, 63% of those who claimed that coffee makes them go were women, which may be supported by research suggesting that women are generally more sensitive to distention than men, and are more likely to suffer from irritable bowel syndrome.

What about you?
Does coffee make you wanna poo?
Let us know

(*The rhyming was not intended, but hey, it works.)

Stay tuned for next week's #BrainBits: "Why do I remember certain things only when I go certain places?"

July 3, 2015

Orange is the New Bleak: What the SHU Can Do to Your Brain

The inmates of Litchfield Penitentiary, the fictional setting for the Netflix TV series Orange is the New Black, are not shy women. 

They’ve landed in prison for murder, fraud, stalking, drug-smuggling, theft, and political activism. They do illegal activities behind the officers’ backs. They make their opinions known loud and clear to one another. And they’re not opposed to throwing a few punches, if duty calls.

But all will cease if you threaten to send them to the SHU. Why?


Netflix

The SHU (pronounced “shoe”), or “security housing unit,” is a separate prison facility designed to isolate inmates from any human contact. While sometimes used to protect the prisoner from harm by others or to themselves (to implement suicide watch, for example), it’s often used as punishment for violating prison regulations. At last count, it’s been estimated that over 80,000 prisoners in the U.S. are housed in the SHU – more than any other democratic country. And while inmates in minimum security may be held in the SHU for a few days at most, those in maximum security prisons can be in solitary for as long as five years.