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Identifying brain’s own facial recognition
system
Excessive Internet use may lead to depression Prof Yash
Pal
THIS UNIVERSE
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Identifying brain’s own facial recognition
system THE ability to recognise faces is so important in humans that the brain appears to have an area solely devoted to the task: the fusiform gyrus. Brain imaging studies consistently find that this region of the temporal lobe becomes active when people look at faces. Skeptics have countered, however, that these studies show only a correlation, but not proof, that activity in this area is essential for face recognition. Now, thanks to the willingness of an intrepid patient, a new study provides the first cause-and-effect evidence that neurons in this area help humans recognise faces — and only faces, not other body parts or objects.
An unusual collaboration between researchers and an epilepsy patient led to the discovery. Ron Blackwell, an engineer in Santa Clara, California, came to Stanford University in Palo Alto, California, in 2011 seeking better treatment for his epilepsy. He had suffered seizures since he was a teenager, and at age 47, his medication was becoming less effective. Stanford neurologist Josef Parvizi suggested some tests to locate the source of the seizures-and also suggested that it might be possible to eliminate the seizures by surgically destroying a tiny area of brain tissue where they occurred. Parvizi used electrodes placed on Blackwell’s scalp to trace the seizures to the temporal lobe, about an inch above Blackwell’s right ear. Then, surgeons placed more electrodes on the surface of Blackwell’s brain, near the suspect point of origin in the temporal lobe. Parvizi stimulated each electrode in turn with a mild current, trying to trigger Blackwell’s seizure symptoms under safe conditions. “If we get those symptoms, we know that we are tickling the seizure node,” he explains. Certain electrodes, however, produced a dramatically different result from the colors and memories that Blackwell typically experienced. When Parvizi sent a signal through these electrodes on the fusiform gyrus, Blackwell told him, “You just turned into somebody else. Your whole face just sort of metamorphosed.” When the stimulation was halted, Blackwell reported that Parvizi’s face had “returned” to normal. The same test caused Blackwell to perceive unsettling distortion in the face of Parvizi’s assistant. But the electrode stimulation affected only Blackwell’s perception of faces of people he could see in person. Stimulating the two points also produced no change in Parvizi’s suit, tie, or skin color, or in other objects around the room. While the electrodes were in place, Parvizi got Blackwell’s permission to turn the clinical probe into a research study, described online in The Journal of Neuroscience. Teaming up with Stanford neuroscientist Kalanit Grill-Spector, who studies the brain areas important in facial recognition, he scanned Blackwell’s brain using functional magnetic resonance imaging (fMRI) and confirmed that the two electrodes that influenced Blackwell’s perception of faces were at points in the fusiform gyrus implicated by Grill-Spector’s previous research. The researchers also recorded brain activity using the electrodes they’d placed on Blackwell’s brain with a technique called electrocorticography. They found that the activity picked up by the electrodes at the two “hot spots” tracked with peak activity at these sites, as measured by fMRI. Cognitive neuroscientist Juan R. Vidal of the Lyon Neuroscience Research Center in France applauds the authors’ use of multiple methods and says the study is the first to prove that the fusiform gyrus plays a causal role in face perception. Previous studies only showed that the area is involved, Vidal says. “The complementary evidence of electrocorticography, fMRI, and brain stimulation will make it possible to study not only the effects of brain stimulation on the local neural networks that process face information, but also how they broadcast their information towards other regions in the brain.” — The Independent |
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Excessive Internet use may lead to depression FOR those who are unable to limit their Internet use, time spent online may produce negative outcomes such as depression, loneliness, and limited face-to-face contacts, say experts. Individuals’ compulsive Internet use (CIU) refers to their inability to control, reduce, or stop their online behaviour, while excessive Internet use (EIU) is the degree to which an individual feels that he or she spends an excessive amount of time online or even loses track of time when using the Internet. Mazer and Andrew M. Ledbetter of Texas Christian University have explored how specific online communication attitudes — such as individuals’ tendency for online self-disclosure, online social connection, and online anxiety — predicted their compulsive and excessive Internet use and, in turn, poor well-being. Mazer and Ledbetter found that an individual’s tendency for online self-disclosure and online social connection led them to use the Internet in more compulsive ways. If a person has poor face-to-face communication skills that individual will likely be more attracted to the social features of online communication, which can foster CIU. Prior research suggests that socially anxious individuals perceive online communication environments as less threatening and, as a result, are more likely to seek out communication in those settings. The findings from Mazer and Ledbetter’s study are not entirely consistent with this claim, which may suggest that researchers adjust their theoretical image of the compulsive user. Whereas previous research frames online communication as a safe activity for the socially anxious to escape their communication anxiety, Mazer and Ledbetter found that compulsive users also experience anxiety when communicating online. To the extent that socially anxious individuals are drawn to the Internet, such anxiety seems to stimulate compulsive, but not necessarily excessive, use. Rather, excessive users seem to have a more realistic perception of online communication as convenient but sometimes limited in communicative effectiveness by a lack of social cues often available in face-to-face interactions. In other words, according to Mazer and Ledbetter’s study, individuals’ anxiety motivates CIU, while efficiency seems to motivate EIU. The study found that CIU, not EIU, led individuals’ to experience poor well-being outcomes. An article describing their study has been published in Southern Communication Journal. — ANI
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THIS UNIVERSE Is it true that planets move in elliptical orbit, whereas natural satellites move in circular orbit? Please explain. That is not true. Satellites we launch around the Earth can be, and generally, are in elliptical orbit. While launching we have to be very meticulous to ensure that they are in circular orbit — by being meticulous I mean that we give the satellite the right amount of radial velocity at the time the satellite reaches the apogee of its elliptic orbit. Can a tube light emit ultraviolet rays if there is a leakage in the tube? A tube light mainly emits ultraviolet rays, which are converted into visible light through interaction with the phosphor coating on the surface of the tube. If there is a leakage in the tube, the ultraviolet tube will not work. Is nuclear energy a renewable or non-renewable resource? I will have to say that in general it is not renewable, because an atom of uranium cannot fission again once it has fissioned. One can regenerate a fissionable variety by converting uranium into plutonium. But that would be cheating. Readers can e-mail questions to Prof Yash Pal at palyash.pal@gmail.com
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NASA rover finds Mars’ soil similar to Hawaii’s CAPE CANAVERAL, Florida: In the first inventory of minerals on another planet, NASA’s Mars rover Curiosity found soil that bears a striking resemblance to weathered, volcanic sand in Hawaii, scientists said. The rover uses an X-ray imager to reveal the atomic structures of crystals in the Martian soil, the first time the technology, known as X-ray diffraction, has been used to analyse soil beyond Earth. China tries building own jet engine HONG KONG: China has designed nuclear missiles and blasted astronauts into space, but one vital technology remains out of reach. Despite decades of research and development, China has so far failed to build a reliable, high-performance jet engine. This may be about to change. China’s aviation sector is striving for a breakthrough that would end its dependence on Russian and Western power plants for military and commercial aircraft. — Reuters
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