A Rat’s Journey Through Virtual Reality

Virtual EnvironmentFew ideas excite the imagination more than virtual reality. We humans use virtual reality for training, entertaining, and even education, but we can also use it to study human and animal behavior. Adaptive behavior, or the ability to adjust to new situations, is influenced by what we see, hear, and experience in our environment; unfortunately, for this reason, it is difficult to isolate the possible stimuli that affect it. The authors of this recently published PLOS ONE paper developed a virtual reality environment to try to isolate and measure the impact of visual and sound cues on rats navigating through a virtual space.

The virtual reality navigation test is based on an experiment called the Morris Water Maze, a standard lab test where a rat swims through water using visual cues on the walls to Virtual Reality Rat Harnessnavigate. The virtual version uses a 14 square-foot room with visual cues projected on each wall and sounds from 4 sides (pictured above). The rat is at the center of the room, wearing a harness (pictured on the right) on a spherical treadmill placed on a three-foot circular table.

Before beginning the navigation tasks, researchers trained nine male rats to move in virtual reality. The rat started from one of 4 random start locations, facing the wall (see video below). The northeast quadrant of the space was designated as the ‘reward zone,’ indicated by a white dot. Upon entry to this zone, the rat was rewarded with sugar water (if only all video games worked this way).

After training, the researchers tested each rat’s ability to navigate to the reward zone using one of three cues: audiovisual, visual, or auditory. Once the rat found the reward zone, a 2-second blackout period was initiated, and then the rat was ‘moved’ back to one of the 4 random start locations. The video below shows the visual cue test.

Scientists found that rats can learn to navigate to an unmarked location based on visual cues—with a moderate amount of training. However, the rats were unable to use the auditory cues to navigate to the reward zone, and instead moved in circles to try to locate it.

Although the rat’s harness may look a little funny, it is a relatively noninvasive test, and since the animal is not in water, like in the Morris Water Maze test, it is easier to combine this test with tools to measure neural and physical variables in the task. Additionally, the virtual maze may contribute to new methodology evaluating the underlying factors in adaptive behavior, specifically because no other cues besides the audiovisual, visual, and auditory defined the spatial location of reward, something that is difficult to achieve in the real world. Despite humans not yet understanding what virtual reality means to us, we can already use it to better understand animal learning and behavior.

Citation: Cushman JD, Aharoni DB, Willers B, Ravassard P, Kees A, et al. (2013) Multisensory Control of Multimodal Behavior: Do the Legs Know What the Tongue Is Doing? PLoS ONE 8(11): e80465. doi:10.1371/journal.pone.0080465

Image 1: doi:10.1371/journal.pone.0080465

Image 2: doi:10.1371/journal.pone.0080465

Video 1: doi:10.1371/journal.pone.0080465

Video 2: doi:10.1371/journal.pone.0080465

The New PLOS ONE Collection on “Sauropod Gigantism – A Cross-Disciplinary Approach”

Sauropod-Collection-600x600 (3) (2)The exceptional gigantism of sauropod dinosaurs has long been recognized as an important stage in the evolution of vertebrates, the presence of which raises questions as to why no other land-based lineage has ever reached this size, how these dinosaurs functioned as living animals, and how they were able to maintain stable populations over distinct geological periods.

We are pleased to announce the publication of a PLOS Collection featuring new research on the complex Evolutionary Cascade Theory that attempts to answer  these questions and  explain how the unique gigantism of sauropod dinosaurs was possible. The fourteen papers that make up the collection address sauropod gigantism from a number of varied disciplinary viewpoints, including ecology, engineering, functional morphology, animal nutrition, evolutionary biology, and paleontology.

Sauropod dinosaurs were the largest terrestrial animals to roam the earth, exceeding all other land-dwelling vertebrates in both mean and maximal body size. While convergently evolving many features seen in large terrestrial mammals, such as upright, columnar limbs and barrel-shaped trunks, sauropods evolved some unique features, such as the extremely long necks and diminutive heads they are famous for. Dr Martin Sander, Professor of Paleontology at Universität Bonn and coordinating author for this series of 14 papers, said of the collection:

“This new collection brings together the latest research on the biology of sauropod dinosaurs, the largest animals to ever walk on Earth. Having been extinct for 65 million years, reconstructing sauropod biology represents a particular challenge. Using a wide array of scientific expertise, often from seemingly unlikely fields, has led to some amazing insights. For example, principles of soil mechanics have been used to ‘weigh a dinosaur’ based on its trackways, whilst the latest in computer modeling can make a dinosaur walk again.

The ultimate question underlying this research is how sauropods were able to evolve their uniquely gigantic body size. The wide-ranging disciplines covered in the collection means that there is a -broad, multi-disciplinary audience for the research, as well as general interest in dinosaurs; therefore, we felt that it was essential to publish such a volume in a leading open-access journal such as PLOS ONE to ensure the widest possible dissemination of our work.”

Readers are able to download “Sauropod Gigantism: A Cross-Disciplinary Approach” not only as a PDF but also as an ebook (.mobi and .epub formats) from the collection page. It will also be available on Flipboard (search “PLOS Collections”).

www.ploscollections.org/sauropodgigantism

Image credits:
Collection Image: Kent A. Stevens, University of Oregon

Watch Out, Here Comes the Round Goby: How One Fish Changed the Danube River

Round Goby (Neogobius_melanostomus)

As big as a pickle and about as intimidating as one, too, the round goby pictured above doesn’t look like an aggressive invader. But this little fish is naturally invasive and uses more than its meager looks to work its way up waterways, conquering native species, settling new habitat, and creating a completely new ecosystem along the way.

Understanding the invasion process of this fish may help scientists better estimate the ecological impacts that invasive species have on their new environments. The round goby is actively invading the German stretch of the Danube River and the authors of this PLOS ONE study used this opportunity to monitor the characteristics of the invasion to better understand the the process. Specifically, they measured the round goby’s population composition, physical characteristics, and feeding and sexual behavior at ten sites as it invaded a 200 kilometer stretch of the upper Danube River from 2009 to 2011. The sites were divided into ten stages of invasion, ranging from already established populations in the lower portion of the river to the ‘invasion front,’ or where they anticipated the goby would invade next.

Scientists found that the invading goby populations differed from their established counterparts when they compared sex ratio, age, size, feeding, and sexual behavior. Contrary to the researcher’s predictions, invaders were more likely to be female, even though male gobies are more exploratory. The authors suggest that a female-dominated invasion front may allow the established, primarily male population to better handle their roles in parental care and territorial defense.

What’s more, the invaders were physically larger than the established populations and appeared to use their size to establish populations in the ‘invasion front,’ rather than depending on rapid reproduction, or a “frequency in numbers” approach. The ‘invasion front’ contained a wider range of food sources, and the invading gobies’ ability to shift their diet from insects and crustaceans to mollusks may have contributed to their increased size. Overall, these results suggest that the round goby’s ability to physically and behaviorally adapt to changing habitats may play a role in invasion success.

All in all, it took the round goby two years to invade and establish populations in the Danube River study area—a rapid change, ecologically speaking. Fierce territorial defenders, 73% of the fish population is now goby in the settled study sites, leaving behind only fish and invertebrate populations able to compete with the goby for food and territory.

The impacts of these changes remain relatively unknown, but studying them may help researchers estimate impacts on ecosystems during future invasions. The Danube River is not the only habitat facing invasion, as this native of both the Black and Caspian Seas has also hitched a ride to the Great Lakes.

Citation: Brandner J, Cerwenka AF, Schliewen UK, Geist J (2013) Bigger Is Better: Characteristics of Round Gobies Forming an Invasion Front in the Danube River. PLoS ONE 8(9): e73036. doi:10.1371/journal.pone.0073036

Photo: Round goby fish by Eric Engbretson

Predicting Movie Box Office Success Using Wikipedia

Iron Man photo by HarshLight

It’s Friday evening and perhaps you’re planing to watch a movie, but will the new release you choose be a blockbuster or a lackluster flop? Well Wikipedia may help predict your choice’s success or failure in the box office, according to a recently published study.

In this study, researchers tracked activity on Wikipedia entries for 312 movies (released in 2010), including aspects like number of views, users, and edits; and compared this activity to the box office success of the movies in a computational model. They found a strong correlation between higher Wikipedia activity before a movie was released, and the box office success of the film.

The study could accurately predict the blockbuster success of movies like Iron Man 2, Shutter Island and Inception, but was unsuccessful with movies such as The Lottery and Animal Kingdom. The scientists attribute the lack of predictability to the amount of data provided for the different types of movies. According to the authors, their analysis can be used to provide reasonable predictions about a movie’s success as early as a month prior to its release.

The study is a foray into using “big data” generated from the social web to predict people’s reactions to a new product- in this case, a movie. Previous studies have used social data, such as tweets related to an event, to estimate public sentiment and reactions. Here, the authors use social data in advance of the ‘event’ to gauge public sentiment after the movie has launched. They conclude, “Our statistical approach, free of any language based or sentiment analysis, can be easily generalized to non-English speaking movie markets or even other kinds of products.”

CitationMestyán M, Yasseri T, Kertész J (2013) Early Prediction of Movie Box Office Success Based on Wikipedia Activity Big Data. PLoS ONE 8(8): e71226. doi:10.1371/journal.pone.0071226

Image Credit: Iron Man Tech by HarsLight

Color and Iridescence in the Stinkbug

fabricant figure 1 pone.0064082

“Beautiful” may not be the first word to describe the stinkbug, but Tectocoris diopthalamus sure are pretty. Pictured above are six specimens, three females (first row) and three males (second row). Do you notice a difference? Hint: it’s all in the colors.

Like mallards, narwhals, and peacocks, T. diopthalamus are sexually dimorphic, meaning that the females and males of the species look physically different. In a new study published last week in PLOS ONE, researchers state that male stinkbugs of this species are more likely than their female counterparts to have large, iridescent patches and to be a deeper shade of red. These eye-catching characteristics may help males attract females and even scare off predators. The colors are variable, however, and subject to a number of environmental factors.

In the study, the researchers used electron microscopy and pigment analysis to study how this stinkbug produces the colors you see above. They identified a type of melanin, which partly make up the blue-green iridescent patches. They also identified a nitrogen-heavy pigment called erythopterin, which produces the orange-red color.  High temperatures and a shortage of nitrogen-rich foods have the potential to affect these respective pigments and lead to a wide range of colorful variations. Neat!

 

Citation: Fabricant SA, Kemp DJ, Krají?ek J, Bosáková Z, Herberstein ME (2013) Mechanisms of Color Production in a Highly Variable Shield-Back Stinkbug, Tectocoris diopthalmus (Heteroptera: Scutelleridae), and Why It Matters. PLoS ONE 8(5): e64082. doi:10.1371/journal.pone.0064082

Image: Image comes from Figure 1 of the research paper.

Home sweet home: Understanding New York City soil fungal communities in green roofs and city parks

Roof garden

Green roofs are growing more common in urban communities around the world. Besides the cost savings associated with these urban green spaces; they also provide ecosystem benefits such as decreased water run-off and habitats for birds and insects.  While green roofs are well studied for their benefits to urban dwellers of the human species, little is known about the impact of their microscopic inhabitants.

In order to better understand these green roof ecosystems, researchers of a recently published paper dug in and evaluated whether or not green roofs in New York City served as a habitat for fungal communities and compared these fungal communities to the microbial composition of nearby city parks.

Their research uncovered that fungi form a diverse community, with many varieties that belong to groups capable of surviving tough conditions like disturbed and polluted habitats. According to the paper:

 Across roofs, there was significant biogeographical clustering of fungal communities, indicating that community assembly of roof microbes across the greater New York City area is locally variable… While fungal communities were compositionally distinct across green roofs, they did not differentiate by plant community.

When the roof and park soil samples were compared, the researchers found that 54% of the fungal strains where shared between park soil and green roofs.

To read more about this research and about how the fungi living on green roofs could be an undervalued piece of the green roof ecosystem click here.

Citation: McGuire KL, Payne SG, Palmer MI, Gillikin CM, Keefe D, et al. (2013) Digging the New York City Skyline: Soil Fungal Communities in Green Roofs and City Parks. PLoS ONE 8(3): e58020. doi:10.1371/journal.pone.0058020

Image:  Image comes from Figure 2 of the manuscript and is an image of a representative green roof from the study.

 

Greetings from Lake Socompa! A Diversity of Life in Extreme Conditions



The photo above comes to us from a remote part of the Andes, at the base of the active volcano Socompa. Lake Socompa is situated here and its whitish stomatolites (a type of layered sediment deposit created by microorganisms) are home to an unexpected diversity of bacterial life.

In research published this week in PLOS ONE, scientists from Argentina and Germany travelled to this remote location, 3570 meters above sea level, to study the lake’s stomatolites and the harsh environment in which they are formed. Stomatolites were found only on the southern shore, where a hydrothermal spring feeds acidic water into the lake. This region of the Andes mountain range receives very little annual rainfall and, due to its high elevation, experiences high levels of ultraviolet radiation. Yet, rather than being inhospitable to life, scientists found that the region’s extreme environmental conditions actually helped to foster “rich, diverse and active ecosystems” within the lake’s stomatolites.  According to the research, the Lake Socompa site is the highest altitude, thus far, where stomatolites are found to form.

Citation: Farías ME, Rascovan N, Toneatti DM, Albarracín VH, Flores MR, et al. (2013) The Discovery of Stromatolites Developing at 3570 m above Sea Level in a High-Altitude Volcanic Lake Socompa, Argentinean Andes. PLoS ONE 8(1): e53497. doi:10.1371/journal.pone.0053497

http://en.wikipedia.org/wiki/Stromatolite

Worth a Thousand Words: Rediscovering an “Extinct” Species

It’s not every day that you come across a living member of an extinct species. Nathan Whelan, a doctoral student at the University of Alabama, had such a day in 2011, when he found specimens of Leptoxis compacta on the banks of the Cahaba River. The last recorded collection of L. compacta more commonly known as the oblong rocksnail, dates back to 1933; the species was formally declared extinct in 2000. The first picture above is Figure 4 from the manuscript, published just last month.

Whelan et al. conducted several tests to confirm that this species above was indeed L. compacta. They compared the shells they found with shells of other known gastropods in the same area. The shells were dissimilar in both pigmentation and pattern. The researchers also compared their findings with archival L. compacta. By using a scanning electron microscope (SEM), they found strong evidence to suggest that they had rediscovered a heretofore “extinct” species.

Citation: Whelan NV, Johnson PD, Harris PM (2012) Rediscovery of Leptoxis compacta (Anthony, 1854) (Gastropoda: Cerithioidea: Pleuroceridae). PLoS ONE 7(8): e42499. doi:10.1371/journal.pone.0042499

 

Worth a Thousand Words: Handedness in Fish

If you look closely at the image above, you’ll see that the mouths of these cichlid fish, Perissodus microlepis, curve in opposite directions. Similar to left or right handedness in humans, many animals exhibit handedness in behavior or morphology. Whether handed behavior is expressed early in development and produces mouth asymmetry or the opposite, that mouth asymmetry produces handed behavior, however, is not well known. The authors of the study “Handed Foraging Behavior in Scale-Eating Cichlid Fish: Its Potential Role in Shaping Morphological Asymmetry” set out to investigate this question and more. The image above is Figure 1 of the article.

Abstract:

Scale-eating cichlid fish, Perissodus microlepis, from Lake Tanganyika display handed (lateralized) foraging behavior, where an asymmetric ‘left’ mouth morph preferentially feeds on the scales of the right side of its victim fish and a ‘right’ morph bites the scales of the left side. This species has therefore become a textbook example of the astonishing degree of ecological specialization and negative frequency-dependent selection. We investigated the strength of handedness of foraging behavior as well as its interaction with morphological mouth laterality in P. microlepis. In wild-caught adult fish we found that mouth laterality is, as expected, a strong predictor of their preferred attack orientation. Also laboratory-reared juvenile fish exhibited a strong laterality in behavioral preference to feed on scales, even at an early age, although the initial level of mouth asymmetry appeared to be small. This suggests that pronounced mouth asymmetry is not a prerequisite for handed foraging behavior in juvenile scale-eating cichlid fish and might suggest that behavioral preference to attack a particular side of the prey plays a role in facilitating morphological asymmetry of this species.

 

Citation: Lee HJ, Kusche H, Meyer A (2012) Handed Foraging Behavior in Scale-Eating Cichlid Fish: Its Potential Role in Shaping Morphological Asymmetry. PLoS ONE 7(9): e44670. doi:10.1371/journal.pone.0044670

Observing World Malaria Day 2012: Sustain Gains, Save Lives

Today is the fifth annual World Malaria Day, commemorated every April 25 to recognize and encourage global efforts to control malaria. This year’s theme, “Sustain Gains, Save Lives: Invest in Malaria,” alludes to the many important advances against the malaria parasite that have been achieved in recent years, but also includes a warning: we must continue to invest in malaria research and maintain our vigilance to ensure that painstakingly earned gains are not surrendered to complacency.

Based on the 251 malaria-related PLoS ONE papers published since last year’s World Malaria Day, it’s pretty clear to us that the research community is maintaining its commitment to this disease. Instead of trying to provide an overview of all of these articles, which cover perspectives as diverse as public health, ecology, and microbiology, we decided to observe the day by highlighting a single article that, like this year’s theme, emphasizes the importance of continued research as the parasite proves itself to be a constantly evolving target.

The study, published last October, monitors drug resistance in the causative parasite Plasmodium falciparum in Mozambique over five years, from 2006 to 2010, as the recommended drug treatment was adjusted. The researchers, led by Jaishree Raman of the South African Medical Research Council, found that the incidence of parasitic resistance to the originally recommended drug regimen increased significantly over the course of the study, from 56.2% at the start up to 75.8% in 2010. This approximately 20% leap in resistance suggested that the preferred treatment at the time would become much less effective as its use increased.

However, the Mozambican Ministry of Healthy preempted this scenario by changing their recommended front-line drug treatment in 2008. The authors weren’t able to study the full impact of this policy change, though, because it was not fully deployed until 2010, at which point the study was winding down – further highlighting the need for continued careful monitoring as new treatments are introduced.

You can learn more about World Malaria Day at Roll Back Malaria and the World Health Organization, and read about some additional malaria papers from last year’s World Malaria day post.

Citation: Raman J, Mauff K, Muianga P, Mussa A, Maharaj R, et al. (2011) Five Years of Antimalarial Resistance Marker Surveillance in Gaza Province, Mozambique, Following Artemisinin-Based Combination Therapy Roll Out. PLoS ONE 6(10): e25992. doi:10.1371/journal.pone.0025992

Image source: eyeweed on Flickr