The Return Of Bed Bugs – Smarter Ones January 13, 2010
Posted by Miss Weird Scientist in Animals, Evolution, Insects, Tough Stuff.Tags: bed bugs, bites, DDT, infestation, pests
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Your mattress may be home to more than your pillow or favorite stuffed animal. It could be the home of bed bugs!
The title reads like a horror movie but for those who have battled it out with bed bugs, it makes a lot of sense. Others might think that ‘don’t let the bed bugs bite’ was just some bedtime line their parents used as a cute joke.
In fact, let’s see now who knew that bed bugs really existed. Try out the poll below (be honest!).
Bed Bug Basics
Bed bugs are small, reddish brown insects that feed on human blood, which engorges them and makes them bigger. They are from the insect family Cimicidae and common bed bugs are formally called Cimex lectularius. They tend to be most active at night, coming out of the cracks in walls or bed frames and other hiding places to get their bloody grub. They can travel in suitcases, so hotels are a hot spot for bed bugs as well as other places that see plenty of people coming and going. Cornell University has an ace fact sheet to give you the lowdown on bed bugs. You can also have some fun playing around on Pest World for Kids, a website created by the National Pest Management Association (NPMA). But let’s get back to finding out why these wee pesky critters have returned and what makes them smarter today.
Gone But Not For Long
Here we have a bed bug hiding in a wood bed frame. The bed bug looks like it's having a Sunday snooze but I bet it's getting rest so it can hunt for fresh blood! Image credit: Thomas Oldani
Bed bugs were once nearly destroyed in our modern environment, where the use of chemicals such as dichlorodiphenyltrichloroethane – otherwise more easily known as DDT – kept these beasties at bay. DDT is a pesticide that is either very useful or very toxic, depending on who you ask or what journal study you read. Ultimately though, it was banned.
The Good And Bad Of DDT
DDT was used to keep mosquitoes under control, mostly because they spread malaria. It was used to keep lice numbers down too. So what happened when it was banned? As somewhat of a side effect of its use, DDT had kept bed bug numbers down. After it was banned, a bunch of other chemicals were used to treat bed bug infestations. The bed bugs, however, got smart and developed resistance to some of these chemicals. That resulted in a big UH OH for society as bed bug infestations are now on a major rise! Scientists from the University of Massachusetts Amherst and Korea’s Seoul National University decided that it would be important to find out more about resistant strains of bed bugs in New York. The work was published in the Journal of Entomology. Let’s see what they discovered, shall we?
When researchers got busy observing bed bugs in New York, they found these pests had mutations in their nerve cells. What does this mean? It means they are resistant to the chemicals used to kill them. Where the chemicals would previously have paralyzed and killed the bed bugs, the mutations mean that bed bugs are now outsmarting their opponents – us!
Let The Bed Bug Collecting Begin!
To get the scoop on bed bug resistance, researchers took a sample of easily controllable ones from Florida and compared these to ones from New York that were harder to deal with. So just how resistant were these little bugs?
Look at this partially engorged bed bug. It probably looks similar to the bed bugs in Milan after they feasted on my blood. Oh, and a fun fact of the day: the Italian word for bed bugs is cimice dei letti.
Researchers found that the bed bugs in New York had up to 264 times the resistance to the modern chemical used to kill bed bugs – deltamethrin. If we picture a nerve cell, it has these little sodium channels on the outer membrane bit. This is where the flurry of nerve impulses come to life. In the New York bed bugs, this nervous system mutation means they can keep feeding long after those Florida ones have been exterminated.
Grossaroo
When I was in grade 3, I made up the word ‘grossaroo’ to describe anything yucky. This word is fitting in the case of what happened to me recently when I spent a month working at an agency in Milan. After a few nights at what seemed to be a nice corporate flat, I began to get loads of itchy, inflamed red bites. I awoke one night to find a flattened-looking bug moving across my otherwise clean, crisp white sheets.
I yelped and quickly squished it with my slipper, only to see it turn into a smattering of blood, which it just took from its recent feeding of my body! Just after, I saw another one. By morning, my bed looked like a crime scene with all those splats of blood and bugs. Eeek! Fortunately, I got moved to a new place and had everything washed. Hopefully, those Milan bed bugs weren’t too hard for the building owners to get rid of, unless they’re resistant beasts like those New York ones.
Bed Bug Warrior To The Rescue
So now you know (if you didn’t already!) that bed bugs do exist. Not only that, but they’re continually evolving to get smarter, doing so in ways that make it harder to get rid of them. For now, you can be smart by being extra cautious when traveling. Always check for signs of bed bugs around the mattress and furniture. Since not everyone shows bites from these little pests, prevention will remain the best line of defense. And while it’s not necessarily smart, it sure is fun when checking for bed bugs to yell “YOU’RE GOING DOWN!” If your parents ask what you’re doing, you can explain that you’re the self-appointed family warrior here to protect everyone from bed bugs.
Image credits: Unless otherwise specified, images courtesy of the National Pest Management Association.
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Evolution Gets Colorful August 24, 2009
Posted by Miss Weird Scientist in Brain Power, Environment, Evolution, Tough Stuff.Tags: autumn, ice age, trees
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Summer is still going strong but soon it will be fall – a time when we can enjoy the pretty autumn leaves. Or as I always like to do, throw leaves at my wee dog and race through the massive piles of foliage.
Unless you’ve traveled a bit and have a sharp eye for detail, you might not have noticed that autumn leaves are usually red in America but yellow in Europe. Seems strange, doesn’t it? If you’re wondering why, then you’re not the only one. Two professors thought about these differences too and they came up with a cool theory.
Prof. Simcha Lev-Yadun of the Department of Science Education at the University of Haifa-Oranim in Israel and Prof. Jarmo Holopainen of the University of Kuopio in Finland had their work published in New Phytologist.
Stepping Back In Time
Red leaves in America serve as a warning flag to ward off insects. But in Europe, none of these evolutionary 'tricks' are needed, which means leaves are yellow.
To find out more, we have to step back 35 million years to sort out the mystery. Up until that time, huge areas of the globe were rich in evergreen forests. Then, a bunch of ice ages and dry spells came into the picture. Lots of the tree species evolved to become deciduous – meaning they lose their leaves depending on the season. Some trees even started to produce red leaves to keep the pesky insects away. But, something else came into play and you might be surprised to learn just what it was!
Look To The Mountains
It’s true. We have to check out the orientation of the mountains to get the scoop on why the leaves evolved to be red in America but yellow in Europe. In North America, north-to-south mountain chains created a protected area, enabling the plants and animals to migrate south or north. Joining them were the insects. So, the leaves in America remained red to continue warding off these annoying bugs.
But in Europe, the mountains are oriented from east-to-west, leaving no protected areas as the ice and other environmental conditions came to visit. Loads of the tree species just couldn’t survive the extreme cold. When they died, so did those insects that needed the trees for their survival. By the time the ice ages were over, those trees that had managed to survive didn’t have to deal with the now-extinct insects. So, no need for red leaves to keep them away!
Curious Minds Want To Know
I asked Simcha Lev-Yadun how he ended up studying leaves. While my background is in the life sciences (medicine and nutrition), I always wonder how people end up in the many different, neat areas of science. He explained:
I wanted to be a biologist and archaeologist since I was ten years old. For me, science is a lifestyle, not a job. At the age of 57…I look backwards and see that I made the right decision.
He also shared his plans to meet up in Scandinavia with his colleague Jarmo Holopainen, where they hope to find out even more about why plants have such cool and different colors.
My Wishful Thinking
While my dog Tiko probably doesn’t care much about leaf color when he dashes through the crisp autumn leaves, I like to understand what makes one leaf a bright yellow and another a brilliant red. Now, if only leaves could somehow evolve to become fluorescent pink, my favorite color. Somehow though, I just don’t see it happening!
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The Recipe For A Perfectly Sticky Web May 31, 2009
Posted by Miss Weird Scientist in Animals, Brain Power, Evolution, Insects, Tough Stuff.Tags: evolve, spider, web
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Have you ever tried to bake a cake, only to find out that when it came out of the oven, it was dry and hard? Maybe you realized that you’d put in too much sugar. Or, maybe you cooked it for too long. Would you believe that spiders have a similar challenge when it comes to spinning their webs? Too much of a good thing can actually leave a web that’s far from perfect.
For this web to catch its prey, it needs to have just the right amount of stickiness and strength. If all goes well for the spider, dinner will soon be served!
For a spider to catch its prey, the web needs to be sticky but still remain strong. If the balance isn’t right, the web won’t catch a bug and it’ll be one hungry and grumpy spider!
A Killer Web Evolves
If you’re a spider, you’ve got your work cut out for you! To catch your prey, you want a web sticky enough that the bug gets caught inside but strong enough that the web doesn’t break from its struggles. With such a fine balance needed, spiders have evolved to get it just right.
Let the Construction Work Begin
To build those impressive webs we see, spiders start by putting down lines of dry silk. Then, they weave spirals of sticky silk to nab their prey. But, spiders of yesteryear didn’t build their webs in quite the same way.
Millions of years ago, spiders would lay down a coating of dry adhesive on these spirals. Rather than stick to the web, a bug would be entangled by these dry spirals. As a cool fact you can throw out at your friends, there are still some spiders today that weave their webs with this dry adhesive – we call them deinopoid spiders.
Yet things began to change, with orb weaving spiders evolving to make webs that were more effective at catching prey. Rather than continue to use this dry adhesive, spiders started to go the sticky route by using wet drops of a glue-like substance. When you think of glue, it seems that the sticker the glue, the better. Not for spiders though!
Curious Scientists Start Investigating
Some scientists started to wonder about these sticky webs – is stickier always better? To find out, Ingi Agnarsson of the University of Puerto Rico in San Juan and Todd Blackledge of the University of Akron in Ohio went on a mission to check out a lot of different spiders. They observed 17 species of orb weaving spiders. You’d have to like spiders quite a bit to watch so many different kinds! The full study results are in the Journal of Zoology.
It’s All About Force
The researchers tested the strength of the strands and the stickiness of them too. How’d they do that? Well, they stuck a piece of sandpaper in the web and then measured how much force was required to remove it.
To break a strand on the web, a specific amount of force is needed. When the researchers put the web to the test, they found that by using anywhere from 20% to 70% of this force needed to break the web, the sandpaper was released.
So, a stickier web might hold the insect but as it continues to struggle, the force would ultimately break strands of the web, causing the insect to be released. Yet, with the glue being a bit less sticky, the insect could pull away from a single strand, but it would get caught by the next one. Since the strands don’t break, they can continue to stick to the bug, making its fight a much harder one.
Spiders Are Impressive
It’s actually really impressive and cool when you think about the work that goes into creating a web with just the right balance of stickiness and strength. As for me, I’ll leave the bug-catching to those smart spiders. I think I’ll just stick to making cakes instead. Pun fully intended! Now if only there was a recipe for making good jokes…
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Hairy Frogs Have An Unusual Defense June 2, 2008
Posted by Miss Weird Scientist in Animals, Tough Stuff.Tags: claws, defense, hairy frogs
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When I think about frogs, I usually picture the cute, little ones hopping around the lake near my house. Well, there are many types of frogs and one in particular is almost the stuff of nightmares! Not only is it a super duper hairy creature but it has a peculiar defense mechanism that has intrigued scientists.
Credit: Gustavocarra for Wikimedia Commons. Check out the claws on this bad boy! If the hairy frog feels threatened, he will bring forth his dangerous claws through the toe pads on his hind legs. Hmmm. I have a feeling that unlike dogs, throwing him a treat won’t make him like me!
Trichobatrachus robustus – as the frog is formally named – breaks its own bones to create special claws that force their way through the frog’s toe pads. It’s thought that this action is performed when the frog is threatened. While we already know that salamanders do something similar by pushing their ribs through the skin to create spiky barbs, the frog’s maneuver is unique! Not only that, but the closest action we’ve seen from other frogs involves bony spines that stick out from the wrist. The difference, however, is that the bones project out naturally, which is different from the hairy frog where the claws force their way out as a form of defense.
Beware The Claw
David Blackburn from Harvard University has studied these interesting frogs; the work is published in the journal Biology Letters. Blackburn found that when at rest, the frog’s claws are sheltered in a bunch of connective tissue. A piece of collagen joins the sharp bit of the claw and a bone found at the tip of the frog’s toe. At the other end of the claw is an attached muscle. Blackburn thinks that when the frog is threatened and under attack, it will contract the muscle, which causes the claw to be pulled downwards. Then, the sharp bit tears away from the bony end and pokes through the toe pad. The end result is a contraption that looks really intimidating. But wait, there’s more to the hairy frog than just these claws! They also have some other neat features. When they breed, male frogs produce long strands of skin and arteries that resemble hair. While researchers aren’t totally sure why the hair exists, they think it might be to bring in more oxygen through the frog’s skin.
Feeling Hungry
In some parts of the world, these hairy frogs are cooked and eaten. Yes, you did just read that correctly – food! The people who hunt the frogs have to be careful not to get hurt by the frog’s claws, so they use spears and similar weapons to capture the creatures. Now, I’m all one for trying new foods but in this case, I think I will pass, thank you very much!
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Blame Your Brain For Temper Tantrums March 9, 2008
Posted by Miss Weird Scientist in Human Body, Psychology and Behavior, Tough Stuff.Tags: brain, teenagers, temper
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Temper tantrums aren’t just a reaction that young kids exhibit when they get upset or angry. Teens can also go berserk over all sorts of issues. Yet, some teens seem to keep their cool while others fly off the handle at just the slightest aggravation. Now, a study suggests that the connection may lie in a teenager’s brain.
Checking Out Families
Nicholas Allen from the University of Melbourne, Australia investigated 137 children between the ages of 11 and 14. As part of the experiment, he also observed their parents. Allen and his team of researchers used questions – such as curfews – that were expected to trigger arguments. They videotaped these disagreements and found that there were loads of differences between the families. Some families kept calm while others were more aggressive and could barely even speak to one another.
What An Enormous Amygdala You Have
When researchers took scans of the children’s brains, they narrowed in on three specific areas. The first was the amygdala, which is what gets people fired up to react impulsively to situations. The other parts they checked out were pre-frontal regions known as the anterior cingulate cortex (ACC) and orbitofrontal cortex (OFC) – areas of the brain that play a role in the more thoughtful types of responses. The results were really interesting!
Researchers found that the boys and girls who reacted more aggressively to the family discussions had bigger amygdalas. As for the temperamental boys, they had smaller ACCs on the left side of the brain, which researchers think explains why they remained aggressive for a longer period of time. On top of that, the boys who had smaller OFCs on the left side were more likely to respond to mopey parents by acting just as moody!
Making Sense Of The Results
Basically, what the results show is that those grumpy, tantrum-prone teens aren’t getting enough control from the pre-frontal parts over the amygdala. So, the impulsive behaviors end up ruling over the thoughtful and more reflective areas of the brain. What’s the end result? You got it – temper tantrums! The results also suggest that the areas of the brain controlling emotions and aggression are different in boys and girls.
My title for this blog entry is actually a bit misleading because it implies that the structural differences in the brain are fully responsible for aggression, when this just isn’t the case. The research gives us helpful clues to one contributing factor in the puzzle of temper tantrums. Learning more about why some teens are calm when others can freak out so easily and intensely can perhaps allow researchers to find better strategies for helping teens handle their aggression. As for my teenage years, I didn’t blame my brain for temper tantrums – I usually just blamed my parents, as most of us teens do!
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Gene Mutations Can Mean Longer Life March 4, 2008
Posted by Miss Weird Scientist in Genetics, Human Body, Tough Stuff.Tags: aging, centenarian, longevity
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While they won’t make someone live forever, researchers recently identified some variations in genes that can allow people to live longer. Your genes are your special and unique instructions that determine things like your hair and eye color.
Say Hello To Centenarians
Nir Barzilai and his team are from the Albert Einstein College of Medicine, which is part of Yeshiva University in New York. Their work involved research subjects of Ashkenazi Jewish descent who were all 100 years of age or older. The fancy term we like to use for people in this age bracket is centenarian. Barzilai and his colleagues identified two gene mutations in the centenarians. If you’re a keen bean, you can read the full, more technical version in the Proceedings of the National Academy of Sciences.
Mutations Can Be Good
You might be wondering to yourself that it seems odd for a mutation to result in greater longevity – something we consider beneficial! The word mutation can leave us thinking of disease, death and just generally bad stuff. While this is often the case, genetic mutations can also lead to positive changes. It’s thought that these changes occur to help humans or other organisms evolve and better adapt to their environment.
Looking Inside The Body
In this study, researchers found that the two mutations affect a receptor for insulin-like growth factor 1 (IGF-1). What does IGF-1 do? If you’re thinking it might influence growth, you’re definitely on the right track. IGF-1 is a guiding force in your body’s growth and maturity. It’s especially dominant during puberty and directs the intense growth and development that occurs during the adolescent years. So, what if the receptor stops working properly, as in the case of the centenarians? If the receptor is just a wee bit faulty, the result is that IGF-1 doesn’t effectively bind to the receptor. Low and behold, the pathway to aging and maturation doesn’t proceed at the same pace and ultimately, it is slowed.
For my male readers, don’t get too hopeful you’ve got the gene mutations. Thus far, the carriers identified are all women. Even more interesting is that the centenarians were shorter than an average woman. These women were approximately 2.5 centimeters shorter than the rest of the population. It makes sense, however, given the role of IGF-1 during the huge pubertal growth spurt.
Our Obsession
In westernized societies, we’re absolutely obsessed with anti-aging and finding the next product to decrease aging – whether it’s the visible, aesthetic signs of aging or the internal, physiological ones. Ironically, people have been getting injections of growth hormone for many years now, with the belief that it slows down the aging process. Given that Barzilai’s study showed it was the people with lower levels of growth hormone who are living longer, these injections could potentially be quite dangerous.
We’re Not Alone
Another thing to keep in mind is that humans are not the only ones with these types of mutations. Worms, flies and mice have similar faulty genes that increase longevity. In the coming years, researchers will probably be in a mad flurry to investigate the genes in other centenarian populations around the world. One of the hopes is to discover strategies to reduce aging in the general population. I guess for now though, I’ll just have to fake it by sticking with my anti-aging face cream!
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It’s Good To Look Like Poo February 22, 2008
Posted by Miss Weird Scientist in Animals, Insects, Tough Stuff.Tags: butterfly, camouflage, caterpillar, poo
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Sometimes, it’s great to look like poo. That is, if you’re a caterpillar! Say hello to the Asian swallowtail caterpillar. It has some neat tricks up its sleeve to successfully stay camouflaged from predators. The first trick comes into play quite early on – when the caterpillar is black and white, with fine spines. Here, it resembles bird droppings. Later on, the caterpillars get older and grow larger, which means it’s a lot harder for the caterpillars to pass themselves off as bird poo. So, as the little critters fatten up, their color changes to a vivid green. Hmmm. Why might being green work well as a camouflage? If you guessed it’s because they can blend in with the leaves, you got it!
Credit: Ryo Futahashi. You can see the wee caterpillar on the left side of the picture looks a lot like bird droppings! On the right, the distinguished fellow is a grown caterpillar – the bright, green color really does make the caterpillar look like the surrounding leaves.
Manipulating The Caterpillar’s Camouflage
In an interesting twist of events, Ryo Futahashi and Haruhiko Fujiwara of the University of Tokyo in Japan, discovered a special way to keep the caterpillar looking like bird droppings. This means that the caterpillar still matures and develops, but it retains its poopy camouflage instead of growing into a green caterpillar that resembles leaves. How did the researchers accomplish this task? It’s not so easy.
It’s All About Genes
You might already be familiar with the concept of genes. Your genes are unique instructions that tell your body how to work. They control all sorts of stuff such as your hair or eye color. Humans aren’t the only ones with genes either! Caterpillar camouflage depends on genes. There are three genes that control the caterpillar’s camouflage. One is responsible for the green color, another for the black color and finally, one for those spikes we see on the very young caterpillars.
Tinkering With Genes
If researchers can find a way to meddle with these genes, they can change the caterpillar’s color. Hint hint. In the case of our Japanese scientists, they did their meddling with a hormone that rules the expression of all three genes. It’s called juvenile hormone. Researchers smeared a synthetic version of juvenile hormone on the back of a young caterpillar. Since the hormone controls the three genes that affect the caterpillar’s color, adding more of the hormone managed to keep the caterpillar looking poopy right through its development. It’s a cool manipulation because it teaches us more about how hormones and genes interact. As for all this talk about poo, I think my next blog post will be on something a bit more pleasant!
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A Crafty Disguise February 6, 2008
Posted by Miss Weird Scientist in Animals, Evolution, Insects, Tough Stuff.Tags: birds, fruit, nematode, parasite
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A very tricky parasite has recently been discovered. What makes it so sneaky? After infecting a certain species of ant known as Cephalotes atratus, the parasitic nematode triggers changes in the ant’s abdomen, which then becomes red and swells. This bulging, red appearance resembles a berry. Birds who feed on this type of fruit mistake the ant for a berry, swoop in and gulp! The bird swallows the ant, which allows the parasite to now infect the bird. Once birds are infected, the parasite can spread through the birds’ feces. In a bizarre circle of events, the ants round off the infectious cycle by gathering up the birds’ droppings so that they – along with their young – can feed off the feces. Smart parasite! It manages to sustain itself through the host ant so it can infect the unsuspecting birds – who think they’re about to eat a juicy, luscious berry!
Credit: Steve Yanoviak of the University of Arkansas. Check out the normal worker ant in the top picture and then compare it to the picture below it, which shows an ant infected with a parasitic nematode. That is one seriously red abdomen! It will be the doom of the ant when a bird mistakes it for a yummy, red berry.
Welcome To The Amazon
This peculiar cycle was observed in the tropical forests in the Amazon and Central America. Robert Dudley of the University of California – Berkeley described his surprise at finding such an intelligent series of events:
It’s just crazy that something as dumb as a nematode can manipulate its host’s exterior morphology and behavior in ways sufficient to convince a clever bird to facilitate transmission of the nematode.
The discovery itself was a chance one as Dudley, Yanoviak and Michael Caspari of the University of Oklahoma were observing a gliding species of ant. They noticed that some of the colony members had bright, red abdomens. Normally, birds don’t even eat ants – partly because of their yucky chemical taste. Yanoviak had some cool things to say about this fascinating discovery:
It’s phenomenal that these nematodes actually turn the ants bright red and that they look so much like the fruits in the forest canopy.
The full article describing the fruit mimicry will be published later this year in the journal American Naturalist. It might be worth a wee read to get the entire scoop on this amazing discovery. Also, research like this doesn’t go without funding – it was partially supported by the National Geographic Society, Amazon Conservation Association and the BBC Natural History Unit.
Evolution
I’m absolutely amazed at the findings. It’s incredible that something as seemingly simple as a nematode can manipulate the ants in such a successful way. It just goes to show that whether a creature is simple or complex, evolution can be one smart cookie!
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Imagination Requires Memory January 9, 2008
Posted by Miss Weird Scientist in Human Body, Psychology and Behavior, Tough Stuff.Tags: episodic, imagination, memory
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As kids and teens, we imagine all sorts of stuff – what we want to be when we grow up or maybe even becoming famous. We hear about kids having vivid imaginations and big dreams for the future. Older adults, on the other hand, can struggle to remember past events and imagine new ones. We obviously know that adults have imaginations too but what makes it different and not always so intense?
A new study performed at Harvard University has shown that the ability of adults to create imaginary scenarios is linked to their ability to recall detailed memories. The full study results can be viewed in the Psychological Science journal.
Episodic Memory
If you didn’t already know, we have different types of memory. One type is called episodic memory. This kind of memory refers to personal memories of past experiences. It’s what lets you go backwards and forwards in the recollection of an event in time. Basically, episodic memories are connected to a specific time and place. If I asked what you had for dinner last night, you would be using episodic memory to answer. Think of episodic memory as being endless snapshots of different moments in your life.
Getting Back To Imagination
So, how does episodic memory relate to imagination? Simple. In order to create and imagine future events, a person needs to remember a previous event. Then, they need to take out bits and pieces from the specific details of the event before they can piece it all back together to form a new, imagined event. There’s even a name for this process – it’s called constructive episodic simulation.
Testing It Out
Psychologists from the university asked young and older participants to respond to various randomly chosen cue words with past and future scenarios. Researchers Donna Rose Addis, Alana Wong and Daniel Schacter then looked at the results, which showed that older adults had a significant reduction in their use of episodic memory to describe past memories and imagined future events. It’s interesting to think about memory being so important in the process of imagination. It just goes to show that all the stuff you do plays a special part in allowing you to imagine new and exciting things, which then creates even more episodic memories.
As for me, I don’t qualify as an older person just yet, I hope. So, I will use my episodic memory to the best of its ability as I imagine what it would be like to finish all of my work this week and take a very long vacation around Europe!
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A Different Kind Of Vision January 1, 2008
Posted by Miss Weird Scientist in Human Body, Tough Stuff.Tags: blind, eyes, retinal ganglion cells, vision
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When most of us think of the term ‘blind,’ we imagine a total loss of sight. Not quite. At least, not in the traditional way we have viewed blindness. A new study led by Russell Foster at the University of Oxford and Steven Lockley of the Brigham and Women’s Hospital in Boston has found that cells at the back of the eyes in blind people can still gauge light levels. These cells then use this information to set the body’s internal clock to daytime or nighttime. The full experiment results can be seen in the journal Current Biology.
Special Cells
A blind person doesn’t have the rods and cones necessary for normal vision. In a healthy, normal eye, rods and cones serve to catch and focus light, thereby creating the crisp images you are able to see each day. Special cells called retinal ganglion cells – located at the back of the eye – help the brain to differentiate between night and day. How do they accomplish this important task? Well, to start, they operate quite differently from rods and cones. Instead of focusing light as rods and cones do, retinal ganglion cells assess the total light available and then transmit this information to the brain. Approximately 3 percent of retinal ganglion cells react to light and release a chemical known as melanopsin. It’s a weird-sounding word but it’s an important pigment that senses light.
Getting Down To Business
So, how did Foster and Lockley test out their ideas about blindness and retinal ganglion cells? To investigate how these special cells influence the body’s ability to register daytime and nighttime, they performed tests on two blind individuals. First, they shone light for 6.5 hours into the eyes of a man who was blind. Then, after using blue light at nighttime, they managed to delay his body clock regulation by 1.2 hours. The result showed that the man’s retinal ganglion cells were able to register the light. But wait, there’s more! They found that the man’s levels of a sleep hormone called melatonin had fallen by 60 percent, which further shows that the man’s body clock was basically tricked into thinking it’s daytime. Foster and Lockley also examined a blind woman and then performed the same tests, which confirmed their findings.
Figuring It All Out
A really cool aspect of this research is that it helps to explain an interesting phenomenon that has puzzled researchers and health professionals. Blind people who have had their eyes removed for various reasons tend to experience really poor sleep quality and patterns. This contrasts with blind people who still have their eyes and don’t tend to suffer from the same sleeping problems.
You can consider yourself fortunate to have the vision that allows you to appreciate the beauty of sunrises and sunsets. At the same time, don’t forget that the light our sun brings plays an important role in regulating not only your own body’s internal clock, but the internal clock of a blind person as well.
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