Sunday Comics: Neuro-Development

A special edition of PhD comics recently won one of Science Magazine's vizualization awards.  Since it is about brain development, it seems only fitting as this week's sunday comic.

Click here for a larger copy.

Week in Review

There were a lot of neuroscience related stories on Science Daily (and elsewhere) this week.  Most likely a result of the recent meeting for the American Association for the Advancement of Science, where scientists from numerous scientific fields presented their research findings and hypotheses, though, here I've only highlighted the neuroscience stories, and at that, only the ones that caught my interest...

 Researchers at the Max Delbruck Center for Molecular Medicine have found a filament protein that appears to be necessary for the sensation of touch (which is still not completely understood at the cellular level).  The research suggests that the protein tethers ion channels on nerve endings to extracellular scaffolds and opens the ion channels in response to vibration or pressure, which results in an action potential in the cell.

An interesting hypothesis has been put forward at Tel Aviv University in Israel to explore the potential for compounds found in scorpion venom to work as pain killers.  Scorpion venom contains neurotoxins that can affect sodium channels on nerve cells.  A specific type of sodium channel is found on nerve cells that respond to painful stimuli.  Thus, if one of the compounds isolated from the venom can inhibit that channel specifically, it would be possible to use it, or compounds like it, as painkillers.

Dr. Douglas Smith at UPenn Medical School proposes that concussions (mild Traumatic Brain Injuries) can have widespread effects throughout the brain as well as long lasting effects.  Since little attention has been paid to concussions in the past, most of this research is new, and much more is needed before we gain a better understanding of how much of an effect concussions can have in the long term.  Given the increasing frequency of concussions seen in military professionals and professional (American) football players and other athletes, this is likely a field that will continue to garner attention in the future.

The steroid hormone Progesterone, which has been known, for over 3 decades, to help neurons survive after a brain injury, is finally about to be tested in phase III clinical trials as a treatment for stroke victims.  My own research is fairly close to this, our lab has looked at similar properties of another steroid hormone, estradiol (more commonly, though incorrectly, known as estrogen).  Both progesterone and estradiol are synthesized in the brains of women and men, and both have been shown to promote the survival of nerve cells after a brain injury.  This is of critical importance because after the initial damage from a stroke or brain trauma, cells around the injury continue to die off in response to signals released by the cells in the damaged area, thus, surrounding healthy tissue also dies.  Progesterone and estradiol have both been shown to lessen the extent of this secondary tissue death, which can mean saving quite a bit of functionality, and for some patients, it may even save their lives.

A new type of PET (positron emission tomography) scan may allow clinicians to diagnose Alzheimer's disease  early.  Alzheimer's is characterized by (amyloid) protein plaques that, as of now, could only be seen at autopsy after the patients had died.  This new imaging technique allows for doctors to see these protein plaques in the brains of living patients, which means it has the potential to be used as a diagnostic tool.

And if that doesn't work, researchers have identified a form of the tau protein (P-tau231) that appears to be elevated in healthy elderly individuals who suffered cognitive decline over a two year period.  Since tau tangles, the equally alliterative and equally nasty step-brother to (amyloid) protein plaques, are also found in the brains of Alzheimer's patients, this particular form may be an early indicator.  Obviously, more long term studies will need to be done to see if any (or how many) of the test subjects are diagnosed with Alzheimer's or continue their decline.

2 studies claim that napping increases humans' ability to learn, one in college students, the other in infants.  Sleep has been known to improve our ability to consolidate and later recall information we have learned (i.e. memory), but these studies claim that midday naps can actually improve our ability to learn, not just our ability to remember.

Neuroscientist Nina Kraus makes the claim that musical education for K-12 kids is something that we should consider keeping when budget cuts are needed, stating: "Music training is not only beneficial for processing music stimuli. We've found that years of music training may also improve how sounds are processed for language and emotion."  


Anti-depressant/Anti-anxiety meds Prozac and Celexa have anti-inflammatory properties, and may have potential as treatments for arthritis. Drugs of this class, known as selective serotonin re-uptake inhibitors (SSRIs), were hailed as a miracle of modern medicine when they first hit the market decades ago, but lately, some have become disenchanted as more comprehensive data suggests that these drugs tend to have only a modest effect.  However, a lot of new research has begun to examine other effects of these drugs, many of them positive, from aiding the rehabilitation of stroke patients, to regenerating bone, and now, maybe, helping to treat inflammation related pain or disease (like arthritis).


This article talks about a finding in rodents showing that sound and smell are linked in a part of the brain that processes these stimuli: the olfactory tubercle.  An overlap of processing is not unheard of, particularly when it comes to the senses.  A great example of this is the McGurk effect, an illusion I posted about a while back where it is the processing of hearing and vision that overlap, and though they usually work together, allowing us to read someone's lips while listening to them, and thus catch what they are saying even if we are at a loud party, when the visual information doesn't match the auditory, we can get a little confused.


Stem cells have been used to restore sight in a mouse model of retinitis pigmentosa, which is a fairly common cause of blindness in humans.


And, of course, there is this study, which showed that people who identify as liberals have higher IQs than those who identify as conservatives.  Also, there was a less dramatic difference between atheists and those who considered themselves religious, with the atheists having slightly higher IQs.  Now, I know this will create quite a stir, but before either side goes crazy, this is one study.  Also, the differences were small (106 vs. 95 for liberals vs. conservatives, and 103 vs. 97 for atheists vs. religious), and, IQ can be debated as to whether or not it is an adequate measure for overall intelligence.  Also, this study was done in "young adults" (read: college kids) and may not be recapitulated in older adults.  All of that being said, it is certainly interesting, as is the hypothesis put forward by the researchers that higher IQ correlates to seeking more evolutionarily novel worldviews (which liberalism, atheism, and even being more nocturnal are all considered to be).  And I can't wait to see more research in this area, as it can tell us something very important about intelligence and perhaps even open-mindedness and creativity (as they relate to intelligence).

What is Science?

I know this is making the rounds on the blogosphere, but some memes are worth repeating...
If you haven't seen any of these symphony of science videos, they not only show you what fun you can have with an auto-tuner, but also, I think, give you a little glimpse into the way scientists see the world universe.  That is, as something of poetic beauty, and, as this little musical points out, it is the unknown that is the most awe inspiring... otherwise, why would we spend all of our time finding answers that only seem to generate so many more questions?



And you thought it was just a bunch of boring facts and numbers...

Apollo Yawn-O

An interesting bit of news making the rounds on the "internets" right now is this story about how Olympic short track skater Apollo Ohno likes to yawn before he competes.  When asked about this purportedly peculiar tradition, Ohno replied: "It makes me feel better... It gets the oxygen in and the nerves out."
I find this little story interesting for a couple of reasons.  First, yawning in anticipation of a competitive event is not that unusual.  According to Robert Provine, professor of psychology at the University of Maryland Baltimore County, "at track and field events, sometimes you'll find participants in the race of their life will be standing around on the sidelines or in the starting block and they may be yawning. Or before a concert, a musician may yawn to prepare for an increasingly energized state".  And this trait is not only obvious in humans.  Ronald Baenninger from Temple University reports that "lions, mandrills, and fighting fish all yawn in anticipation of metabolically expensive events such as feeding or fighting."  So, Ohno's pre-skating tradition may not be so unusual.  
But since the subject has been broached, I'm curious... In seeing that picture or in reading this post on yawning, have you felt the urge to yawn?  Maybe let one or two slip by?  Sadly, I've already yawned several times just in writing this.  So, what causes Apollo Ohno, or more generally, the rest of us to yawn?  And why are yawns contagious?


The truth is no one really knows.  Several hypotheses have been put forward over the years, with the most popular going something like this: yawning is caused by either excessive carbon dioxide or a lack of oxygen either in the lungs or in the circulation.  This idea is so prevalent, it can still be found in some medical texts.  However, in a study conducted in the 1980s by the same Robert Provine quoted above, subjects were exposed to environments that were either high in carbon dioxide or high in oxygen with neither having an effect on yawning.  So, neither low oxygen, nor high carbon dioxide are to blame for our yawns, but how about heat, or, rather, overheating?  The latest hypothesis to be put forward is that yawning may act to cool our overheated brains, kind of like the radiator in your car.  The more the engine works, the hotter it gets, the radiator takes the ambient air, which is cooler and uses it to bring down the temperature of the engine.  In a similar way, our brains actually increase in temperature as a result of use and fatigue, and yawning takes in cooler, ambient air, and increases blood flow in the face and head, thus carrying cooler blood past the brain.  The evidence for this hypothesis comes mainly from a single study that showed that contagious yawning could be decreased by holding a cold pack up against one's head (or by making a conscious effort to breathe through the nose, which also cools the brain).  Of course, more study will be needed to say whether or not yawning is meant to cool our brains, but it is interesting that certain diseases, like multiple sclerosis, which have a component of thermodisregulation (inability to regulate temperature) are also characterized by excessive yawning.
Regardless of whether or not cooling the brain is the end goal, it appears that the overall purpose of yawning is to help us stay awake and alert, which is why being tired or bored are the most common triggers, and why athletes will yawn before a big event as they try to get focused.
  
But what of the contagiousness of yawns?  Aside from the fact that a person with a cool brain seems to be less susceptible to catching your yawn, what else do we know?
Much like the function of yawning, several attempts have been made to try and explain the contagiousness of yawning. When the oxygen and carbon dioxide hypothesis was still considered valid, it was proposed that the yawns of people around you expelled excess carbon dioxide into the air you breathe, causing you to take in excessive carbon dioxide, and thus you yawn.
Obviously, there are a couple problems with this... first, yawning is not caused by changes in carbon dioxide (or oxygen) as we saw above.  Second, even if carbon dioxide levels were to blame, it has been shown that just watching video of people yawning, or hearing someone yawn, or reading about yawning can all cause people to yawn more (and since the stimulus yawn isn't even happening in the same room or at the same time, there is no change in CO2 or oxygen levels).
Okay, so what else?  Well, another hypothesis that came into vogue after it was discovered that carbon dioxide was not to blame was that yawning somehow activated the mirror neuron system.  The mirror neuron system is made up of neurons that fire not only when we perform a certain action, but when we see the same action being performed by someone else.  Many neuroscientists speculate that these mirror neurons are important for our ability to imitate others (which is how we learn to do many things like talk, write, play sports, learn a trade or craft, etc.)  However, studies published in 2005, and in 2009 that used fMRI imaging to examine the brains of people who were "catching" a yawn suggests that the parts of the brain where the mirror neurons reside don't seem to be activated in this process.
So, the latest hypothesis gets back to the now more accepted idea that yawns are meant to stave off exhaustion and increase alertness.  Examples of contagious yawning in other social animals (like baboons) suggests that there may be an evolutionary benefit to catching a yawn.  While some suggest that the contagiousness of yawns in social animals reflects empathy and a means to strengthen social bonds by synchronizing behaviors (like when to go to sleep), others have suggested that the raised awareness brought on by a yawn provides enough of an evolutionary incentive for it to "catch" on.  For example, many species of birds feed in large groups because feeding is a dangerous activity for them, one that usually involves lowering their head and eyes to the ground to pick up food.  A single bird by itself could get caught unaware by a predator whenever its head is down, but in a large group of birds, it is much more likely that when one bird has its head down, several others have their heads up, and are looking around.  Thus, each bird can feel safe pecking at the ground, confident that one of his neighbors will sound the alarm if a predator approaches.  When you have animals that live together in groups, and are likely on synchronized sleep/wake cycles (like baboons and early humans), then yawning may act as another sort of alarm.  When one in the group yawns, he or she is signifying fatigue, or a need to stay alert.  Others that follow this lead will likely reap the same arousing effect and be more likely to have the alertness and focus needed to successfully elude an approaching predator, or to have a successful hunt.  Thus contagious yawning may have evolved in our primate ancestors as a means for increasing alertness when it was needed, and yawning athletes appear to be a manifestation of this held-over trait, giving them added alertness before they enter the "hunt" for gold.

Who wants to live forever?

Fans of either the Highlander movies (or tv show) or the rock band Queen may recognize this song, but as a serious response to the question, I think more and more people are seeing only the upside of increased longevity.  Certainly, a large amount of scientific research and unscientific profiteering attest to the quest for immortality (or at least a few more good years).  Whether it be engineering heart valves or using stem cells to regenerate failing organs, or attempting to maintain a calorie restricted diet, many people are working toward this lofty goal.  A little while back, Philadelphia's public radio station WHYY had an interesting conversation with journalist/author Greg Critser on his new book: Eternity Soup which chronicles much of the science and pseudoscience centered around increasing human life span.  You can listen here, and check it out for yourself.  I particularly liked the parts of the discussion on the use of steroid and growth hormones, and maybe I missed it because I was working while I had the radio on, but I would have liked to hear more about the rapidly emerging field of regenerative medicine.

Facilitated Communication Debunked

Finally!  And I say finally, not because it took some great feat, or long, arduous process to disprove this nonsense, but because the test was so ridiculously simple I can't believe it has taken this long.  If you don't know what facilitated communication is, or what I'm talking about, here's an old post where I talk about it, or you can watch this video to see why it has been in the news recently (and if you do watch the video, you'll see why I am amazed that anyone could believe that this was anything other than the "facilitator" doing all of the typing, and yet, people did, including doctors at the medical center, and Dr. Nancy Snyderman.)

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As for the supposed brain scans mentioned in the video, apparently no such scans were done, and, of course, the facilitated communication has been shown not to work.  So, what was this test that has taken since November of last year to carry out?

"Objects and words were shown to the patients in the absence of the facilitator who was then called back into the room. The patient was then asked to say what they had seen or heard."

Yeah, that's it.  And guess what, Rom Houben, the Belgian man in the story couldn't correctly answer the questions posed when the "facilitator" came back into the room, suggesting that she had been controlling the typing all along.  Go figure. 

Eerily similar to the creationist movement...

Resolutions have been passed by the state governments of Utah and South Dakota to try and deny climate change.  The resolution in South Dakota even calls for "a balanced teaching of global warming in public schools".
Read on...