Archive for the ‘biology’ Category
You’ve probably heard the old adage about eating carrots for good vision. Well, there is some truth to it. Carrots contain a high concentration of β-carotene which gets broken down in the intestines to form the aldehyde (hydrocarbon) form of vitamin A, cis-retinal. Vision deteriorates in the absence of vitamin A because cis-retinal is trafficked along the protein, opsin, to produce electrochemical signals from light.
Our retinas perceive light in tiny particles called photons. As soon as these photons hit the retina, they isomerize cis-retinal to trans-retinal. Trans-retinal then bonds to opsin to form rhodopsin. Rhodopsin is a purple pigment in the photoreceptor cells of the retina that reads blue-green light. This is the first step of the phototransduction cycle where photon energy is transferred to a series of signaling and diffusing protein complexes.
Mutated forms of rhodopsin will be folded and transported differently and could lead to deteriorated vision or blindness. In more rare cases, mutations can cause rhodopsin to be constantly activated, even in the absence of light. Hypersensitivity, autoimmune disorders, and mutations can all cause rod cells in the retina to undergo apoptosis or cellular self-destruction. This sort of degradation of the retina will ultimately lead to deteriorated vision and eventually blindness.
The absorbance of cis-retinal is optimized at approximately 100 nanometers less than rhodopsin and it is a very rigid molecule because of the arrangement of its double bonds. Thanks to isomerism, we can see in color as opposed to ultraviolet! As all of the above demonstrates, our ability to see involves a series of complicated and precisely regulated bio-chemical processes, and carrots play their role.
We will be exploring more about vision loss and blindness in the upcoming GLIMPSE issue 10, Blindness. In the meantime, let us know your thoughts, research, questions, or experiences related to the topic.
If you’re interested in the chemistry of vision and why we perceive the section of the electromagnetic spectrum that we do, you might also be interested in GLIMPSE, issue 4, Color, and the article on “Human Potential for Tetrachromacy” by Kimberley A. Jameson and the online supplementary article.
Myya McGregory is the GLIMPSE 2012 Science Writing Intern. She is a junior double-majoring in chemistry and economics at Williams College. She enjoys music, dance, and literature.
The Mental Mechanics of Motion
by Myya McGregory
George Balanchine, New York City Ballet master choreographer, once said, “see the music, hear the dance,” implying that dance is felt. Anyone who has ever attempted any type of movement that could be considered dance has probably been told to “feel the music” or perhaps “stop thinking and just move,” which can be frustrating, since in order to disconnect one’s brain, it must first be engaged. Learning new movements is not necessarily an easy task. Those who do it well make it look easy, but everyone goes through the same mental mechanics.
Here is where the production of γ-aminobutyric acid or GABA comes in. GABA is a neurotransmitter that is produced from the decarboxylation of glutamate in the brain.
Levels of GABA in the motor cortex play a large role in the development of our motor function and how we learn movement sequences. Studies in Current Biology by Stagg, Bachtiar and Berg have shown that the degree of motor learning and a decrease in the the magnitude of GABA are positively correlated. That means that the degree of short-term motor learning increases as GABA levels decrease in the motor cortex. As we try to learn motor functions, we engage the cerebellum which produces the enzyme catalyst that helps turn glutamate, the neurotransmitter that excites our neurons and helps us learn, into GABA which in turn inhibits neural activity.
Streeter et al. conducted a subsequent study that pinpoints what type of activity can increase our GABA levels. His team used magnetic resonance spectroscopy to monitor the levels of GABA in two different participant groups. One group was actively engaged in walking for sixty minutes three times a week for twelve weeks. The other group dedicated that same time to yoga. They found that subjects who participated in yoga had higher levels of GABA in the thalamic system overall. Yoga experts experienced a GABA increase of 26%. Those that were yoga beginners experienced a 13% increase. As you try harder to learn, your brain works to help mitigate GABA, but it’s these increased levels of GABA early on that make the initial learning curve the steepest.
GABA, however, is not completely bad, since it also boosts our mood and helps relieve stress. Therefore, the more you know, the more you can relax and in this case enjoy the calming benefits of yoga.
So next time you’re struggling in a dance class (or a yoga or zumba class, or struggling with any movement based activity for that matter), know that it gets better if you just stick with it — the secret’s in the GABA.
A Look at the Work of Pina Bausch
Scientific research has shown that we perceive art (especially movement based art) with the help of mirror neurons. Mirror neurons are a set of cells in the brain that allow us to recall an action and imagine that action as our own so that we can experience it ourselves either vicariously or viscerally. This is what makes dance specifically such an emotive and provocative art form.
With the passing of the great choreographer and dancer Pina Bausch, many are reflecting on how she hacked the brains of her audience in pushing the boundaries of dance theatre. As a master of empathy, Pina Bausch was able to explore the range of the audience’s reaction to familiar movements and experiences. As shown in her movie Pina 3D, she was able to work with a wide range of themes while always maintaining the human experience as the common thread.
Her dancers adored her for her compassion and care. She encouraged them to be vulnerable and from there they were able to understand her vision.
Her skill was telling stories of the human experience by incorporating colloquial movement language. One project that did this exceptionally well was «Kontakthof». Performed by three different age groups on different occasions, this piece unearths a series of social issues, fears, and insecurities in a lighthearted and occasionally disturbing manner. The setting however and the dancers themselves were quite colloquial and the dance moves of the dancers were in fact their own. As one watches this piece with dancers of each age group the perception of the piece changes. The same movements on a 15 year old girl will not be read the same on a 65 year old woman. What does this say about our mirror neurons and our ability for perception? Are our brains biased?
Today, more dancers and performance artists are beginning to push the boundaries of our perception with their work by considering the neural responses of their visual cues. Over the course of the next few weeks GLIMPSE will be continuing this discussion with our readers, so share your thoughts and stay tuned!
OK admit it: we all enjoy a little bit of gossip every now and then. Whether it be about a movie star or the next door neighbor, it piques our interest—especially if it happens to be negative. Perhaps a case of good old schadenfreude is the reason we take a guarded amusement in gossip, or maybe the simple fact that it’s more interesting to find out a person received a perfect score on a test through cheating rather than spending long hours at the library. But have we ever considered that hearing a juicy bit of gossip might actually be good for us? Researchers at Northeastern University concluded that people remember a face better when they hear negative gossip about a person than if they hear positive or neutral gossip, suggesting an evolutionary benefit to our guilty pleasure. The ability to easily spot a possible liar, cheat, or all-around bad person provides social protection; we wouldn’t want to spend time with people who might betray or deceive us. While that seems like an obvious statement, what makes this study fascinating is that it’s all happening at the unconscious level. Even if what we hear is untrue, it’s in our nature to be cautious.
Not only does the research give us a good excuse for our interest in gossip but it’s also a little reassuring. It reminds us that that we (excuse the pun) look out for ourselves. Our well-being is a priority, regardless of whether we realize it or not.
Are science and religion as mutually exclusive as most like to believe? Perhaps not, NPR suggests in this series of articles and interactive media relating the study of neuroscience to religious experiences. GLIMPSE contributor Dr. Michael Persinger makes an appearance in part two of the series, ‘The God Spot.’ The article explores the possibility that the perceived presence and feeling of God is simply a product of temporal lobe stimulation. Persinger subjects the author of the article to his ‘God helmet,’ a contraption that stimulates the right temporal lobe with weak magnetic fields (the same helmet written about in our Text issue). And indeed, the author felt something when the helmet was placed on her head. While it might seem like an oversimplification to claim that spiritual feelings exist only because of neurons firing off, it’s a compelling idea that forces us to truly question what our brains are capable of.
We’re especially intrigued by ‘The Biology of Belief’, part four of the series. The article examines how much power the mind actually exerts over the body. Persinger claims the temporal lobe is responsible for spiritual encounters, but we have no say in the actions of our neurons. AIDS Researcher Gail Ironson studied the effects of prayer on HIV patients and found that those who prayed regularly maintained a higher volume of immune cells than those who did not believe in God. These findings may not be conclusive but they are refreshing. We may not be able to bend spoons and open doors with the power of thought, but being able to stave off an incurable illness is not a bad trade-off.
Is figuring out a way to measure faith harmful? Does it make religious experiences any less valuable if one knows the neurological source? The idea that science and religion have possibly found common ground can be a bit of an uncomfortable one; however, maybe we’ve seen them as opposing fields of studies for too long. Perhaps now is the time to start thinking differently.
The idea of infinity can be difficult to wrap our minds around—it’s been talked about in math classes and used in many a hyperbole, but the idea of ‘forever’ is still so abstract. Now you can experience a glimpse of visual infinity for yourself with National Geographic’s “Infinite Photograph.” At first it just looks like a single picture. But with a single click, you find out it’s made of countless other pictures. You keep clicking only to find out each of those pictures is made of more pictures. And those pictures? Yup, just more pictures. Try and stop clicking. Go ahead. Believe us—it’s not that easy. And because this is National Geographic, each photograph is stunning.
The photo mosaic dates not too far back in the late twentieth century. Both Robert Silvers and Joseph Francis pioneered the art form through computer programming. The effect is a sort of meta-art, with some pretty incredible results. The concept of a mosaic has roots in pointillism, an art form popular during the 1800s. Pointillism is a painting technique where many small dots are created in patterns to produce a larger, single image. This, along with photo mosaics, are great representations of interconnectedness, the breakdown of how all the parts contribute to a whole.
The most recent Infinite Photo is one of marine and terrestrial life on the South Pacific island of Mo‘orea. Besides being an excellent way to kill ten minutes of your time at the office or wherever you may be, it’s also quite educational. By continuing to click on an individual photo (more clicking!), you’ll learn a specie’s common and scientific name. This photograph is a physical, interactive, beautiful representation of infinity. And it’s awesome.
Researchers have made an interesting discovery about ancient rock art in Western Australia: it’s alive. While most rock art fades over time, the colors on these caves have remained bright and vibrant after an astonishing 40,000 years. How did this happen? ‘Living pigments,’ the term dubbed by the researchers to explain this phenomenon. The pigments of the original painting were eventually replaced by pigmented microorganisms. These microorganisms have replenished themselves countless times over the years, resulting in the artwork’s brightness. Whether or not the artists knew their pigments would survive is unclear, but in a world where the passage of time generally decays, breaks down, and rusts relics of the past, it’s fascinating (and refreshing) to see that every so often, time is on our side.
Is this article about a new species of mistletoe terribly relevant and life-changing? No, probably not. But are we feeling a little warm and fuzzy and slightly less jaded because it’s the holiday season? Yes! And doesn’t it seem like more than a coincidence that the species was confirmed only a few days before Christmas? Well okay, it’s arguable, but we’re leaning towards yes on that one, too. And if mistletoe doesn’t catch your fancy, the article also highlights other beautiful and rare plant discoveries made in 2010.
Forget about astrology — a study published by the Nature Neuroscience journal suggests the season you’re born in might have a drastic effect on your biological clock and personality. Scientists performed experiments on mice, raising them from birth and weaning them in simulated winter and summer light cycles. They found the biological clocks in winter mice were much more susceptible to be affected with the changing of the seasons; their daily activity also slowed down. The mice born in the ‘summer’ exhibited no major changes in their brains’ behavior. While the findings are not conclusive, we at GLIMPSE think it’s pretty interesting our seemingly arbitrary relationship with the seasons can have a such big impact on our development. So for those of you with birthdays December through March, take a break from blaming mother dearest for all your problems and start shaking your fist at mother nature.