AP Biology class blog for discussing current research in Biology

Author: lp719

Sorry, What Did You Say?

Credit: Cyclone

Are you able to zone out in a noisy room and just focus on one thing? I know that I am able to do this when I am really into a book and I block every other sound out when I am reading. Are you able to focus on only one voice in a room of many?

A recent study has shown that the brain has the ability to focus so intensely that it can make a single voice seem like the only sound in a room full of other noises. Nima Mesgarani and Edward Chang of the University of California, San Francisco, studied what happens in the brains of people who are trying to follow one of two talkers. Scientists call this scenario “cocktail party problem.” In the study, electrodes were placed under the skulls of three people for an epilepsy treatment. The electrodes picked up high gamma waves from nerve cells. The pattern and strength of the high gamma waves reflect which sounds the people were paying attention to. The scientists gave the test subjects a signal word and told them to focus on that speaker once that word was spoken. Throughout this experiment, the researchers recorded brain activity and sorted that activity into patterns that reflect voices and words. They found that before the signal word was uttered, the patterns in the brain showed up as a mishmash, but once that word was heard, the subjects’ attention focused on that one voice and their brain activity shifted to a pattern similar to that seen when the listener heard only a solo speaker.

Micheyl said, “scientists already knew that attention influences perception, but the new results demonstrate that this is a literal, direct reflection of auditory attention at the neural level.” These results help explain how people are able to pick out a single speaker from a multitude of incoming sounds. Scientists hope that with these results and a deeper understanding of the brain’s power to focus, it will be possible to better treat people who can’t sort out sound signals effectively, something that can decline with age.

The next time you are in class and feel like you can’t listen to your teacher because the rest of the students in your class are making a lot of noise, try to focus on only your teacher’s voice. Your brain has the power to do this, so if you put your mind to it, you will be able to see that it isn’t so hard to listen to one person amidst a group of jumbled noises!

Sweet Genes Not So Sweet

Do you enjoy eating foods that taste sweet? Do you also like to eat meat? Well, what would you do if you ate so much meat that your genes responsible for detecting the sweet taste suddenly stopped? Would you be upset? I certainly would be. Thankfully, humans do not have to worry about this problem yet, but a recent study shows that animals that are specialized carnivores have lost the power to taste sweetness.

Credit: Martin Heigan

The study analyzed twelve different mammals and their sweet detector gene Tas1r2. The researchers found that in seven out of the twelve animals, Tas1r2 experienced mutations. The gene carried disabling glitches in hyenas, otters, fossa, banded linsang, sea lions and two different kinds of seals. What these animals have in common is that they are all predators. The study’s coauthor Gary Beauchamp believes that this means that the mutations in Tas1r2 “could easily spread through populations.”

While these carnivores have lost their ability to taste sweetness, this loss is not universal among meat eaters. For example, animals like red wolves are fervent meat eaters, but have not lost their genetic sweet spot. Beauchamp believes that the carnivores that have not lost the function of this gene will soon lose it in the future due to evolution.

However, there are many arguments in opposition to Beauchamp’s proposal. Animals that do not specialize in meat may have also lost their ability to taste sweetness. Chickens eat both plant and animal foods, but do not seem to notice sweetness in their food and appear to lack a functional Tas1r2. Huabin Zhao of Wuhuan University in China believes that chickens are just one reason that Beauchamp’s conclusion is not convincing. Zhao suggests that “narrow diet specialization might be a better explanation” for the meat-eater sweet-loss scenario.

The only way to determine if Beauchamp’s conclusion is valid is

to see if there will be disabling genetic glitches in Tas1r2 in other types of carnivores in the future. If this does occur, then this genetic mutation has the potential to shape the evolution of carnivores. Similar to these carnivores, people have also had their “use-it-or-lose-it” sensory evolution. For example, humans are not great at detecting odors and even worse when it comes to noticing pheromones, the strong animal-to-animal chemical communications. Only time will tell if the mutations of Tas1r2 will spread to all carnivores, but let’s hope humans do not lose the functionality of their sweet detector gene because sweet food tastes too good!

Lack of Sleep = Excited Brain

Credit: Richard Pagani

Do you get enough sleep during the week? With exams, college applications and numerous extracurricular activities, it is easy to lose track of time and stay up all night working on homework. Personally, I know that I do not get enough sleep every night. However, I did not know that the later people stay awake, the more their brains become active and overly excited.

A recent study has shown that as people stay up late during the night, their nerve cells become more jumpy the longer they are awake. The study consisted of six people staying up all night and having researchers measure their brain responses. The leader of the study, Marcello Massimini of the University of Milan, found that people’s brains become more reactive as hours awake accumulate. To test for signs of altered brain function, the researchers delivered a jolt of magnetic current to the subjects’ skulls. This stimulated an electrical response in the nerve cells. Through electrodes, the scientists measured the strength of this electrical response in the frontal cortex, the region of the brain that is involved in decision-making.

The researchers observed that after a night of sleeplessness, the subjects’ electrical responses were stronger than they were the previous day. The scientists found that this overreaction disappeared after a night’s sleep. Therefore, the study showed that during the hours people are awake, the brain accumulates connections between nerve cells as new things are learned. They think that this excitability in the brain may explain why sleep deprivation can trigger seizures and why hallucinations can accompany an all-nighter because these are events that are usually marked by extreme nerve cell excitation.

Neuroscientist Christopher Colwell of UCLA says that this is “an important finding [because] sleep deprivation is an area of huge interest because most of us do not get enough sleep.” The results from this study help clarify what goes wrong in a brain deprived of sleep. These scientists have also found that the results have a link to depression because it has been found that sleep deprivation can reverse the symptoms of depression. Massimini and his team believe that because the brain is in a boosted state of excitability when it lacks sleep, people who suffer from depression do not exhibit the same symptoms of it when they have not gotten enough sleep. However, this state of excitability is not good for the brain because it needs time to rest and repair itself. Sleep sweeps the brain of extraneous clutter, leaving behind only the most important connections. Therefore, when people are sleep deprived, their brain has so many connections between nerve cells that it does not have the ability to only pick out the most important connections. Thus, this state of excitability is not good for the brain because the brain is never given a break. After learning this, I will definitely try to adjust my sleeping schedule so my brain does not overwork itself!

To learn more about the effects of sleep deprivation on the brain and behavior click on the link below!

Tasting Colors?!

Credit: Carly Bodnar

Last year while doing a practice SAT reading section, I came across a story about a condition called synesthesia. If you have never heard of it before, you’re not alone. Synesthesia is a very rare, sense-mixing condition in which people taste colors or see smells. Sounds crazy, right? According to studies, 3% of the world population claim that they experience some form of synesthesia. I couldn’t believe it! I didn’t understand how people could taste and see intangible things.

A recent study shows that there is a pattern among people who have the condition that close family members have similarly entangled senses. Scientists have examined several genes to see which ones contribute to the phenomenon. Scientists hope that the uncovering of the condition’s genetic basis might reveal why it occurs and potentially help develop cures for similar neurological diseases.

The study, led by neuroscientist David Eagleman, studied a region of chromosome 16, the chromosome believed to hold the gene responsible for synesthesia. Eagleman and his colleagues believe that a defect in this gene may blend connections in the brain, leading to insufficient regulation of the brain’s neural bridges. David Brang from the University of California, San Diego explains, “It could be that everyone is born with global connectivity in the brain, and over time most undergo a refining process.” Another theory proposes that synesthesia is caused by a shift in the brain’s balance of chemicals. This hypothesis is supported by the fact that people can have synesthetic experiences if they take hallucinogens.

Eagleman believes that the continued study of synesthesia could more clearly illustrate how genetic changes affect changes in brain function. Finding more information about synesthesia can help uncover how different brain areas interact with each other. The discovery of neurological networking problems could also help find cures for or advancements in other degenerative neurological and genetic diseases. So for those of you who didn’t believe that such a condition existed, it does! Keep in mind, though, that these types of diseases often have genetic origins, another reason why there is not that much information on these obscure diseases. However, at a time when advancements and discoveries in genetics are so prevalent, Eagleman is confident that more information about this condition will be uncovered soon. Remember, next time you are doing a SAT reading section, don’t forget about the information given in those stories, they could give you insight into potential scientific discoveries!

Eek! I hate that sound!

Do you get goose bumps when you hear nails dragged across a chalkboard? Do you have to cover your ears and wonder why this sounds makes you so uncomfortable? If you have, fear no more!

A recent study was conducted by scientists to discover why certain noises make people cringe. The study consisted of 104 people who listened to six different chalkboard squeaks. After listening to the squeaks, the people had to rate their discomfort level. The researchers then measured changes in the listeners’ vital signs and skin conductivity, indicators of stress, while replaying the two most annoying squeaks. The sounds contained frequencies that ranged up to 12,000 hertz (Hz) and beyond. The scientists thought that maybe filtering out the highest frequencies would make the fingernail-scraping sound less chilling. Yet, they found that cutting out the lowest or highest frequencies did not change the listeners’ level of discomfort. They did, however, find that removing all tones between 2,000 and 4,000 Hz made the experience a little less painful. The researchers are not completely positive why this sound range makes the experience worse, but they believe that maybe the ear canal naturally resonates with those frequencies more than others. The sensitivity to this sound range can very well be why people with noisy jobs tend to lose hearing in this frequency range first.

Ouch! That hurts!

Scientists concluded from this study that sound waves alone are not the only factor that makes for this distressing experience. Knowing that a screech comes from a chalkboard, instead of something pleasant, adds to the listener’s irritation. The fact that the brain associates hearing squeaks on a chalkboard with an unfavorable experience triggers the listener to react negatively when such sounds are heard. Scientist Randolph Blake at Vanderbilt University believes that vision is another factor that adds to the painfulness of the experience. He said, “I’m convinced that watching somebody scrape their nails on a chalkboard will make the experience even more unpleasant.” Thus, our reactions to certain sounds are part psychological and part physical.

These findings help illuminate why people react badly when they hear unpleasant sounds. Although the study has not found a solution to making these experiences somewhat more enjoyable, these findings have helped scientists determine which sound frequencies people are more sensitive to, which could help researchers learn more about our the complexity of our hearing and its sensitivity. What other types of sounds give you the chills? Do you think that researchers and scientists can find a way to make unpleasant noises more enjoyable? What do you think their ideas and methods would be? As for now, try to stay away from fingernails dragging across a chalkboard, because although you may know why your body does not like hearing it, you sure don’t want to have to go through the pain!

Human Health in the Hands of a Naked Mole Rat?

Our genome is similar to that?!

         What do you think of when you see a naked mole rat? Do you think it is hideous because it has no fur? Do you think you would want to pet it? Whatever you think about this animal, you would never expect that it could improve human health. Who knew they could be the key to increase the human life span? Yep, that’s right! Naked mole rats, as ugly as they may be, are now considered extremely helpful and important in designing treatments for fatal diseases.

            A recent study discovered that the newly deciphered genome of the naked mole rat could help researchers learn more about evolution and even help design better treatments for diseases like cancer and stroke. Scientists believe that this genome will help decipher the naked mole rat’s unique traits, behaviors and social characteristics.

            Scientists who deciphered the naked mole rat’s genome used shotgun sequencing to read it. The naked mole rat was raised in a lab and once it was an adult, the scientists studied its genome. They read long sequences of the nucleobases that make up the rat’s DNA and then lined them up to find where they overlapped. Once they read the complete genome, the researchers compared it to the genomes of humans and mice.

            The researchers found multiple mutations in the naked mole rat’s genes that correlate to its characteristics. They found that the rat had turned off several genes related to vision because they live in the dark. They also saw a mutation in the gene that functions in hairlessness, which explains why these rats are bald. Naked mole rats live in low-oxygen burrows and stroke and heart attack deprive parts of the body from oxygen. By comparing the genome of the naked mole rat to the human genome and discovering how they survive in this type of low-oxygen environment, scientists can design more effective treatments to improve diseases that deprive the body of oxygen. The researchers sequenced the whole genome and will make it available free online, so groups that study genes involved in cancer and longevity can compare those genes to the mole rat’s genome. You can even look it up online and determine for yourself which genes you think are similar to ours!

            This new information about the naked mole rat’s genome can be extremely helpful for treatments that could increase the human life span and improve human health. Who knows, maybe the deciphering of the genome could even lead to find the fountain of youth! What do you think? Do you think the rat’s genome is similar enough to ours that scientists can design more effective medication for diseases? How far do you think these researchers are able to go? If you are unsure, just be sure of one thing, the next time you see a naked mole rat, be sure you look at it with a different perspective because in twenty years that very rat’s genome may lead to the cure for cancer!

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