January 31, 2013
You may have never seen a zebrafish in person. But take a look at the zebrafish in the short video above and you’ll get to see something previously unknown to science: a visual representation of a thought moving through a living creature’s brain.
A group of scientists from Japan’s National Institute of Genetics announced the mind-boggling achievement in a paper published today in Current Biology. By inserting a gene into a zebrafish larvae—often used in research because its entire body is transparent—and using probe that detects florescence, they were able to capture the fish’s mental reaction to a swimming paramecium in real time.
The key to the technology is a special gene known as GCaMP that reacts to the presence of calcium ions by increasing in florescence. Since neuron activity in the brain involves rapid increases in concentrations of calcium ions, insertion of the gene causes the particular areas in a zebrafish’s brain that are activated to glow brightly. By using a probe sensitive to florescence, the scientists were able to monitor the locations of the fish’s brain that were activated ay any given moment—and thus, capture the fish’s thought as it “swam” around the brain.
The particular thought captured in the video above occurred after a paramecium (a single-celled organism that the fish considers a food source) was released into the fish’s environment. The scientists know that the thought is the fish’s direct response to the moving paramecium because, as an initial part of the experiment, they identified the particular neurons in the fish’s brain that respond to movement and direction.
They mapped out the individual neurons responsible for this task by inducing the fish to visually follow a dot move across a screen and tracking which neurons were activated. Later, when they did the same for the fish as it watched the swimming paramecium, the same areas of the brain lit up, and the activity moved across these areas in the same way predicted by the mental maps as a result of the paramecium’s directional movement. For example, when the paramecium moved from right to left, the neuron activity moved from left to right, because of the way the brain’s visual map is reversed when compared to the field of vision.
This isn’t the first time that GCaMP has been inserted into a zebrafish for imaging purposes, but it is the first time that the images have been captured as a real-time video, rather than a static image after the fact. The researchers accomplished this by developing an improved version of GCaMP that is more sensitive to changes in calcium ion concentration and gives off greater levels of florescence.
The accomplishment is obviously a marvel in itself, but the scientists involved see it leading to a range of practical applications. If, for example, scientists had the ability to quickly map the parts of the brain affected by a chemical under consideration as a drug, new and effective psychiatric medications could be more easily developed.
They also envision it opening the door to a variety of even more amazing—and perhaps a bit troubling (who, after all, really wants their mind read?)—thought-detecting applications. “In the future, we can interpret an animal’s behavior, including learning and memory, fear, joy, or anger, based on the activity of particular combinations of neurons,” said Koichi Kawakami, one of the paper’s co-authors.
It’s clearly some time away, but this research shows that the concept of reading an animal’s thoughts by analyzing its mental activity might move beyond science fiction to enter the realm of real world science applications.
January 23, 2013
Next time you’re reading about a scientific finding and feeling a bit skeptical, you may want to take a look at the study’s authors. One simple trick could give you a hint on whether the work is fraudulent or not: check whether those authors are male or female.
According to a study published yesterday in mBio, men are significantly more likely to commit scientific misconduct—whether fabrication, falsification or plagiarism—than women. Using data from the U.S. Office of Research Integrity, this study’s authors (a group that includes two men and one women but we’re still trusting, for now) found that out of 215 life science researchers who’ve been caught misbehaving since 1994, 65 percent were male, a fraction that outweighs their overall presence in the field.
“A variety of biological, social and cultural explanations have been proposed for these differences,” said lead author Ferric Fang of the University of Washington. “But we can’t really say which of these apply to the specific problem of research misconduct.”
Fang first became interested in the topic of misconduct in 2010, when he discovered that a single researcher had published six fraudulent studies in Infection and Immunity, the journal of which he is editor-in-chief. Afterward, he teamed up with Arturo Casadevall of the Albert Einstein College of Medicine to begin systematically studying the issue of fraud. They’ve since found that the majority of retracted papers are due to fraud and have argued that the intensely competitive nature of academic researcher engenders abuses.
For this study, they worked with Joan Bennett of Rutgers to break down fraud in terms of gender, as well as the time in a scientist’s career when fraud is most likely. They found that men are not only more likely to lie about their findings but are disproportionately more likely to lie (as compared to women) as they ascend from student to post-doctoral researcher to senior faculty.
Of the 215 scientists found guilty, 32 percent were in faculty positions, compared to just 16 percent who were students and 25 perecent who were post-doctoral fellows. It’s often assumed that young trainees are most likely to lie, given the difficulty of climbing the academic pyramid, but this idea doesn’t jive with the actual data.
“Those numbers are very lopsided when you look at faculty. You can imagine people would take these risks when people are going up the ladder,” said Casadevall, “but once they’ve made it to the rank of ‘faculty,’ presumably the incentive to get ahead would be outweighed by the risk of losing status and employment.”
Apparently, though, rising to the status of faculty only increases the pressure to produce useful research and the temptation to engage in fraud. Another (unwelcome) possibility is that those who commit fraud are more likely to reach senior faculty positions in the first place, and many of them just get exposed later on in their careers.
Whichever the explanation, it’s clear that men do commit fraud more often than women—a finding that shouldn’t really be so surprising, since men are more likely to indulge in all sorts of wrongdoing. This trend also makes the fact that women face a systemic bias in breaking into science all the more frustrating.
January 17, 2013
Barnacles are renowned for the size of their penises. The strange-looking creatures, which live inside shells glued to rocks or boat hulls, have outsized members that are among the longest in the animal kingdom relative to their size—their penises can stretch up to eight times their body length. Barnacles can even change the size and shape of their penis depending on the amount of wave action in their ocean real estate.
Perhaps this is why the sex lives of barnacles have long been of interest to scientists—luminaries such as Darwin, among others, closely studied the subject. Until recently, though, scientists recognized just two methods of reproduction in the species, and both left unanswered questions.
Pseudo-copulation, in which the penis enters a neighboring barnacle’s shell and deposits sperm, has been observed, but this method restricts them to reproducing only with others in their vicinity. Scientists have also observed that individual barnacles with no neighbors can reproduce, and they assumed this was accomplished through self-fertilization, because most barnacles are hermaphrodites.
Now, though, researchers at the University of Alberta, Edmonton and Bamfield Marine Sciences Centre in British Columbia seem to have discovered a new reproduction method while studying the gooseneck barnacle (Pollicipes polymerus), upending more than 150 years of theory. Previously, the researchers had noticed that in other studies of the gooseneck barnacle, self-fertilization was never observed. They also saw sperm leaking from the barnacles in the field, which made them consider the possibility that barnacles could pick up sperm from the water.
In the study, the scientists collected gooseneck barnacles—both isolated and in pairs—along with their fertilized eggs from Barkley Sound in British Columbia to take back to the lab so they could genetically analyze the paternal combinations. The DNA of the fertilized eggs revealed that none of the isolated barnacles had produced embryos through self-fertilization—so one hundred percent of these eggs must have been fertilized by capturing sperm from the water.
Surprisingly, though, even some of the barnacles that resided in pairs had embryos that had been fertilized with sperm from a non-neighbor. This left one possibility: that the barnacles release their sperm into the ocean and let the water carry it to distant neighbors. This type of fertilization has been observed in other marine animals that can’t or don’t move, but it was always assumed that barnacles can’t reproduce in this way.
The authors point out that this mode of reproduction may be unusually common in this particular barnacle species because of the small size of their penis—but the fact that this phenomenon occurs at all opens the door to re-thinking the biology of these creatures. Other barnacle species might also have more mating options, with fathers coming from farther afield than previously thought.
Learn more about the ocean from the Smithsonian’s Ocean Portal.
January 15, 2013
For years, when museums, textbooks or other outlets attempted to illustrate what a particular ancient human skeleton would have looked like in the flesh, their method was admittedly unscientific—they basically had to make an educated guess.
Now, though, a group of researchers from Poland and the Netherlands has provided a remarkable new option, described in an article they published in the journal Investigative Genetics on Sunday. By adapting DNA analysis methods originally developed for forensic investigations, they’ve been able to determine the hair and eye color of humans who lived as long as 800 years ago.
The team’s method examines 24 locations in the human genome that vary between individuals and play a role in determining hair and eye color. Although this DNA degrades over time, the system is sensitive enough to generate this information from genetic samples—taken either from teeth or bones—that are several centuries old (although the most degraded samples can provide information for eye color only).
As a proof of concept, the team performed the analysis for a number of people whose eye and hair color we already know. Among others, they tested the DNA of Władysław Sikorski, a former Prime Minister of Poland who died in a 1943 plane crash, and determined that Sikorski had blue eyes and blonde hair, which correctly matches color photographs.
But the more useful application of the new method is providing new information. “This system can be used to solve historical controversies where colour photographs or other records are missing,” co-author Manfred Kayser, of Erasmus University in Rotterdam, said in a statement.
For example, in the paper, the researchers analyzed the hair and eye color for a female skeleton buried in the crypt of a Benedictine Abbey near Kraków, Poland, sometime between the 12th and 14th centuries. The skeleton had been of interest to archaeologists for some time, since male monks were typically the only people buried in the crypt. The team’s analysis showed that she had brown eyes and dark blond or brown hair.
The team is not sure yet just how old a skeleton has to be for its DNA to be degraded beyond use—the woman buried in the crypt was the oldest one tested—so it‘s conceivable that it might even work for individuals who’ve been in the ground for more than a millenium. The researchers suggest this sort of analysis could soon become part of a standard anthropological toolkit for evaluating human remains.
January 14, 2013
Last summer, a study published in the Proceedings of the National Academy of Sciences sparked a new round of worries about the dangers of smoking pot—especially for those who start smoking at younger ages. The study found that consistent marijuana use gradually eroded cognitive functioning and IQ, and with the legalization of recreational marijuana in Colorado and Washington, it’s made an appearance in a number of articles arguing that legalized pot poses a serious health hazard. Today, though, a new study published in the very same journal—and using the very same data set—suggests that the case against marijuana is a little less cut-and-dry.
Ole Røgeberg, a researcher at the Frisch Centre for Economic Research in Norway, analyzed the same survey results and found that the declines in cognitive abilities could be entirely attributed to socioeconomic factors. As a result, “the true effect” of marijuana use, he argues, “could be zero.”
Røgeberg is careful to note that his reinterpretation of the data doesn’t entirely discredit the original study, but he does write that its “methodology is flawed and the causal inference drawn from the results premature.”
Both the new and old studies draw upon a data set of 1,037 individuals from Dunedin, New Zealand, who were followed from their birth (either in 1972 or 1973) until they turned 38. At the ages of 18, 21, 26, 32 and 38, each of them were interviewed and scored for marijuana use. The original study found that IQ decline increased proportionately with cannabis dependence—especially for those who started smoking earlier on—and the authors concluded that using the drug was the cause of the decline.
Røgeberg, though, dug a little deeper into the data. He found those who started using marijuana during adolescence were disproportionately likely to have poor self-control and conduct problems in school—both factors that are themselves correlated with low socioeconomic status. In particular, members of the study with these traits were more likely to come from a Maori background, a group indigenous to New Zealand that has much higher unemployment, poverty and incarceration rates than the country’s population as a whole.
Numerous other studies have shown that low socioeconomic status adolescents are more likely to experience steeper IQ declines during adulthood. (Researchers hypothesize this is a result of being exposed to less intellectually stimulating environments.) As a result, Røgeberg wondered, could socioeconomic factors explain the IQ declines originally attributed to marijuana?
In his simulation, he tested whether socioeconomic environmental factors (dropping out of school, being exposed to less stimulating environments, and so on) could conceivably drive the same IQ declines reported in the group without turning to marijuana as an explanation. His statistical analysis found that these other factors could indeed completely account for the cognitive declines observed.
For support, he also points to a 2002 Canadian study that also asked whether long-term marijuana use impacted IQ, but with data entirely from middle-class survey participants. That paper found that IQ only decreased for current cannabis users, and when even heavy users stopped smoking, their IQ rebounded. Since that study largely excluded socioeconomic factors and did not find a permanent trend, he feels that it supports his argument that such factors play a major role.