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Author Archives: Megan Edwards
Supporting Hepatitis Awareness with Open Access Hepatitis Research
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Music, Language, and the Brain: Are You Experienced?
Have you ever thought about everything that goes into playing music or speaking two languages? Musicians for example need to listen to themselves and others as they play, use this sensory information to call up learned actions, decide what is important and what isn’t for this specific moment, continuously integrate these decisions into their playing, and sync up with the players around them. Likewise, someone who is bilingual must decide based on context which language to use, and since both languages will be fairly automatic, suppress one while recalling and speaking the other, all while continuously modifying their behavior based on their interactions with another listener/speaker. All of this must happen quickly enough for the conversation or song to flow and sound natural and coherent. It sounds exhausting, yet it all happens in milliseconds!
Playing music or speaking two languages are challenging experiences and complex tasks for our brains. Past research has shown that learning to play music or speak a second language can improve brain function, but it is not known exactly how this happens. Psychology researchers in a recent PLOS ONE article examined how being either a musician or a bilingual changed the way the brain functions. Although we sometimes think of music as a universal language, their results indicate that the two experiences enhance brain function in different ways.
One way to test changes in brain function is by using Event Related Potentials (ERPs). ERPs are electrical signals (brain waves) our brains give off immediately after receiving a stimulus from the outside world. They occur in fairly predictable patterns with slight variations depending on the individual brain. These variations, visualized in the figure above with the darkest red and blue areas showing the most intense electrical signals, can clue researchers into how brain function differs between individuals and groups, in this case musicians and bilinguals.
The ERP experiment performed here consisted of a go/nogo task that is frequently used to study brain activity when it is actively suppressing a specific behavior, also called inhibition. In this study, the authors asked research participants to sit in front of a computer while simple shapes appeared on screen, and they were to press a key when the shape was white—the most common-colored shape in the task—but not when purple, the least frequent color in the task. In other words, they responded to some stimuli (go) and inhibited their response to others (nogo). This is a similar task to playing music or speaking a second language because the brain has to identify relevant external sensory information, call on a set of learned rules about that information, and make a choice about what action to take.
The authors combined and compared correct responses to each stimulus type in control (non-musician, non-bilingual) groups, musician groups, and bilingual groups. The figure above compares the brainwaves of different groups over time using stimulus related brainwave components called N2, P2, and LP. As can be seen above, these peaks and valleys were significantly different between the groups in the nogo instances. The N2 wave is associated with the brain’s initial recognition of the meaning or significance of the stimulus and was strongest in the bilingual group. The P2 on the other hand, is associated with the early stages of putting a stimulus into a meaningful context as it relates to an associated behavior, and was strongest in the musician group. Finally, the authors note a wave called LP wave, which showed a prolonged monitoring response in the bilingual group. The authors believe this may mean bilinguals take more time to make sure their initial reaction is correct.
In other words, given a task that involved identifying a specific target and subsequently responding or not responding based on learned rules, these results suggest that musicians’ brains may be better at quickly assigning context and an appropriate response to information because they have a lot of practice turning visual and auditory stimuli into motor responses. Bilinguals, on the other hand, show a strong activation response to stimuli along with prolonged regulation of competing behaviors, likely because of their experience with suppressing the less relevant language in any given situation. Therefore, despite both musicianship and bilingual experiences improving brain function relative to controls, the aspects of brain function they improve are different. As games and activities for the purpose of “brain training” become popular, the researchers hope this work will help with testing the effectiveness of brain training.
Citation: Moreno S, Wodniecka Z, Tays W, Alain C, Bialystok E (2014) Inhibitory Control in Bilinguals and Musicians: Event Related Potential (ERP) Evidence for Experience-Specific Effects. PLoS ONE 9(4): e94169. doi:10.1371/journal.pone.0094169
Images are Figures 1 and 2 from the article.
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New Year, New Species
Rock lizards, pigment producing fungus, eagle rays, ant garden parasites, and Antarctic sea anemones: new species are discovered all the time and there are likely still millions that we simply haven’t yet discovered or assessed. Species are identified by researchers using a range of criteria including DNA, appearance, and habitat. PLOS ONE typically publishes several new species articles every month, and below we are pleased to help introduce five that were discovered in 2013.
Thought previously to consist of only three species, this group of lizards are now seven distinct species. They appear very similar to one another, making it difficult to tell which characteristics define different species, and which are just variations present in the same species. They also have a variety of habitats, from trees to rocky outcrops, and the genus is widespread. Iranian, German, and Portuguese scientists used genetic variation and habitat to help describe four new species of Iranian rock lizards, Darevskia caspica, D. Kamii, D. kopetdaghica, and D. schaekeli. These techniques, in addition to analysis of the the lizards’ physical features, as in the photo of the four new species’ heads at the top of this page, helped to identify them definitively.
Found in soil, indoor environments, and fruit, Talaromyces atroroseus produces a red pigment that might be good for manufacturing purposes, especially in food. Some other species of this type of fungus produce red pigments, but they are not always as useful because they can also produce toxins. T. atroroseus produces a stable red pigment with no known toxins, making it safer for human use, according to the Dutch and Danish researchers who identified it.
Fish, like rays and sharks, are at high risk for extinction as a group, but as rare as they are, they can be plentiful enough in some locations to make them undesirable to locals. The discovery of the Naru eagle ray, Aetobatus narutobiei, splits a previously defined species, A. flagellum, that, due to its shellfish-eating habits, is considered a pest and culled in southern Japan. The discovery by Australian and Japanese scientists that this species is actually two species prompted the authors to encourage a reassessment of the conservation status of the rays.
Fungal parasites in ant gardens
In the Brazilian rainforest of Minas Gerais, leafcutter ants cultivate fungus, their primary source of food, on harvested leaf clippings. But scientists from Brazil, United Kingdom, and The Netherlands have discovered that their food source is threatened by four newly identified mycoparasites, Escovopsis lentecrescens, E. microspora, E. moellieri, and Escovopsioides nivea. The parasites grow like weeds in the ants’ gardens, crowding out more desirable fungus used for food. Unfortunately for the ants, researchers expect there are many similar unidentified species yet to be discovered.
Living on the previously undocumented ecosystem of the underside of the Ross Ice Shelf in Antarctica, American researchers discovered the first species of sea anemone known to live in ice, Edwardsiella andrillae. Fields of anemone were discovered using a scientist-driven remote-controlled submersible. The anemone burrows and lives within the ice and dangles a tentacle into the water beneath, almost as if it is dipping a toe in the water to test the chilly temperature.
Look here to read more about new species.
Citations
Ahmadzadeh F, Flecks M, Carretero MA, Mozaffari O, Böhme W, et al. (2013) Cryptic Speciation Patterns in Iranian Rock Lizards Uncovered by Integrative Taxonomy. PLoS ONE 8(12): e80563. doi:10.1371/journal.pone.0080563
Frisvad JC, Yilmaz N, Thrane U, Rasmussen KB, Houbraken J, et al. (2013)Talaromyces atroroseus, a New Species Efficiently Producing Industrially Relevant Red Pigments. PLoS ONE 8(12): e84102. doi:10.1371/journal.pone.0084102
White WT, Furumitsu K, Yamaguchi A (2013) A New Species of Eagle RayAetobatus narutobiei from the Northwest Pacific: An Example of the Critical Role Taxonomy Plays in Fisheries and Ecological Sciences. PLoS ONE 8(12): e83785. doi:10.1371/journal.pone.0083785
Augustin JO, Groenewald JZ, Nascimento RJ, Mizubuti ESG, Barreto RW, et al. (2013) Yet More “Weeds” in the Garden: Fungal Novelties from Nests of Leaf-Cutting Ants. PLoS ONE 8(12): e82265. doi:10.1371/journal.pone.0082265
Daly M, Rack F, Zook R (2013) Edwardsiella andrillae, a New Species of Sea Anemone from Antarctic Ice. PLoS ONE 8(12): e83476. doi:10.1371/journal.pone.0083476
Figures are all from their respective articles.
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Awkward Silences: Technical Delays Can Diminish Feelings of Unity and Belonging
Smooth social interaction is fundamental to a sense of togetherness. We’ve all experienced disrupted conversations—some caused by human awkwardness and others by breakdowns in technology. The content of our interactions does influence our connection to each other, but the form and process of communication also play a role. Technical delays that occur below our conscious detection can still make us feel like we don’t quite click with the person we are trying to communicate with. The authors of a recently published PLOS ONE article, funded by a Google Research Award, investigated how delays introduced into technologically mediated conversations affected participants’ sense of solidarity with each other, defined as unity, belongingness, and shared reality.
For this research, conducted at University of Groningen, The Netherlands, participants in three sets of experiments sat in cubicles with headsets connected to computers (conditions that many of us with desk jobs can relate to) and were asked to talk about holidays for five minutes with an assigned partner. Some conversations were uninterrupted. Others were manipulated by introducing a one-second auditory delay. Some pairs knew about the delay and others did not. Afterward, the conversationalists completed a questionnaire about their sense of unity, belonging, understanding, and agreement with their partners.
Researchers found that those participants whose conversations were interrupted expressed significantly diminished feelings of unity and belonging. Awareness of technical problems had no apparent effect on perceived solidarity. Even acquaintances stated that they felt a disconnect, though to a lesser degree, than participants who did not know each other. Despite participants expressing that they felt less unity and belongingness with their partner even when they had the opportunity to attribute it to technical problems, technology did not get a free pass on the delayed signal. Those with an interrupted connection also expressed less satisfaction with the technology. Points may have been lost for both relationships and telecommunications.
In a world where our interactions are increasingly mediated by computers and mobile phones with less than perfect signals, the authors suggest that this research provides insight into how our daily interactions may be affected. The method of communication we choose may influence our personal and business relationships, especially among strangers. The authors also posit that technology meant to improve long distance communication by imitating face-to-face interaction may not measure up to expectations if it is not executed without interruptions or delays. Perhaps this is something to consider during your next awkward phone call or video conference— though your awareness of technology as a possible barrier ultimately may not make a difference in how you perceive the person on the other end of the line.
Citation: Koudenburg N, Postmes T, Gordijn EH (2013) Conversational Flow Promotes Solidarity. PLoS ONE 8(11): e78363. doi:10.1371/journal.pone.0078363
Images: First image by Villemard is in the public domain. Second image is Supplemetary Figure 1 from the article.
Burning the Candle at Both Ends: Intertidal Ant Species Can Work Night and Day
If you’ve ever experienced rush hour traffic, you know firsthand that most humans base our schedules roughly around the rise and setting of the Sun, during daylight hours. However, the Australian intertidal ant, Polyrhachis sokolova, must instead schedule its busy day of foraging in the mangrove forest according to the rise and fall of the tide. Low tide can occur day or night, and to function effectively in both the brightest and darkest conditions, these ants possess several useful eye structures—not unlike the pupils in our eyes, or night vision goggles—that help them adjust to different light levels so that they can find food.
There are thousands of ant species that can have a variety of habitats, morphologies (shapes), and navigation methods. Australian intertidal ants use vision to identify landmarks like trees, and celestial cues like the angle of starlight to find their way. Low tide, whenever that may be, is the best time for foraging, so these ants need to see in all light levels without the assistance of flashlights or sunhats. Exactly how they manage to adapt to such a wide range of light conditions was investigated and described in a recent PLOS ONE study.
To learn more, researchers made tiny casts of intertidal ants’ eyes using fingernail polish. They flattened the casts and examined them under a microscope. Ants have compound eyes, meaning that their eyes are made of many tiny facets, or eye units, compared to simple eyes like ours that only have one eye unit each. Researchers counted the number of facets in each compound eye and measured each one’s diameter. The eyes were cast at different times—10am and 10pm—to inspect how the eye structures changed in dark versus light conditions. The light sensitivity of the eyes was calculated based on this morphological data.
Intertidal ants’ compound eyes each have around 596 facets and are similar to the eyes of other ant species specifically adapted to darker conditions. Eyes that “see” in the dark tend to have larger lenses and be extremely sensitive to light to get the most out of the little available light. This night vision adaptation would typically limit an ant’s ability to function in daylight because bright light would overload the photoreceptors in these highly sensitive structures, but the researchers found other mechanisms that protect these ants’ eyes, restricting the amount of light that can enter—like a pupil—by making the openings that allow light to pass smaller. This mechanism helps the ants adapt their night-vision eyes to bright daylight. This type of pupil is seen in other nocturnal ants but had not been found previously in ants that forage during the day.
Finally, to assist in navigation, the researchers found yet another structure in the ants’ eyes: special light detectors that act like skylights and help determine direction by sensing the angles of light sources in the sky. Therefore, Australian intertidal ants do not have the very best day or night vision, but they instead sacrifice some of their ability to see well in each condition in order to see “adequately” in both.
Citation: Narendra A, Alkaladi A, Raderschall CA, Robson SKA, Ribi WA (2013) Compound Eye Adaptations for Diurnal and Nocturnal Lifestyle in the Intertidal Ant, Polyrhachis sokolova. PLoS ONE 8(10): e76015. doi:10.1371/journal.pone.0076015
Image Credits: Images are from Figures 1, 2, and 3 from the manuscript.
Perceiving Is Believing
Do we really sing as well as we all think we do in the shower? Exactly how complex is Mel Taylor’s drumming in Wipeout? How we hear things is important not just for the field of music research, but also for the fields of psychology, neurology, and physics. There is a lot more to how we perceive sound than sound waves just hitting our ears. PLOS ONE recently published two research articles exploring music perception. One article focuses on how perceiving a sound as higher or lower in pitch—the frequency of a musical note relative to other notes—than another sound is influenced by different instruments and the listener’s musical training. The other explores rhythm, including musicians’ perception of rhythmic complexity.
Pitch is the frequency of a sound, commonly described using the words high or low. The quality of tone, or timbre, of an instrument, on the other hand, is less easy to define. Tone quality is often described using words like warm, bright, sharp, and rich, and can cover several frequencies. In the study presented in “The Effect of Instrumental Timbre on Interval Discrimination,” psychology researchers designed an experiment to determine if it is more difficult to perceive differences in musical pitch when played by different instruments. They also tested whether musicians are better at discriminating pitch than non-musicians (you can test yourself with this similar version) to see if musical training changes how people perceive pitch and tone.
The researchers compared the tones of different instruments, using flute, piano, and voice, along with pure tones, or independent frequencies not coming from any instrument. As you can see from the figure above, each instrument has a different frequency range, the pure tone being the most localized or uniformly “colored.” Study participants were given two choices, each choice with two pitches, and decided which set of pitches they thought were the most different from each other; sometimes they compared different instruments or tone qualities and sometimes, the same.
The researchers compared the participants’ answers and found that changes in tone quality influenced which set of pitches participants thought were the most different from each other. Evaluation of the different timbres showed that musicians were the most accurate at defining the pitch interval with pure tones, despite their training in generally instrumental tones. Non-musicians seemed to be the most accurate with both pure and piano tones, though the researchers noted this might be less reliable because non-musicians had a tendency to choose instrumental tones in general. Interestingly, both groups were faster at the pitch discrimination task when pure tones were used and musicians were better at the task than non-musicians. Everyone chose pitch intervals more accurately as the differences between the pitches became larger and more obvious.
Another group of researchers tested how we perceive syncopation, defined as rhythmic complexity, in their research presented in “Syncopation and the Score” by performing an experiment playing different rhythms to musicians. They asked musicians to rank the degree of complexity of each rhythm.
The study was limited, with only ten participants, but in general, the rhythm patterns thought to be the most complex on paper were also perceived as the most complex when the participants listened to them. However, playing the same patterns in a different order sometimes caused listeners to think they were hearing something more or less syncopated. The authors suggest that a rhythm pattern’s perceived complexity depends upon the rhythm patterns played before and after it.
Both research studies highlight the intersection of music and music perception. We don’t need to be musicians to know that music can play tricks on our ears. It may be that some of us are less susceptible than others to these tricks, but even trained musicians can be fooled. Look here for more research on music perception.
Citations:
Zarate JM, Ritson CR, Poeppel D (2013) The Effect of Instrumental Timbre on Interval Discrimination. PLoS ONE 8(9): e75410. doi:10.1371/journal.pone.0075410
Song C, Simpson AJR, Harte CA, Pearce MT, Sandler MB (2013) Syncopation and the Score. PLoS ONE 8(9): e74692. doi:10.1371/journal.pone.0074692
Image: Spectrograms of four tones – Figure 1A from Zarate JM, Ritson CR, Poeppel D (2013) The Effect of Instrumental Timbre on Interval Discrimination. PLoS ONE 8(9): e75410. doi:10.1371/journal.pone.0075410