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Prof. Jiyun Lee receives the U.S. FAA Achievement Award
- Ensures the safe operation of aircraft by monitoring ionospheric changes caused by solar storms.
KAIST’s Aerospace Engineering Department’s Professor Jiyun Lee has received an award from the U.S. Federal Aviation Administration (FAA), in recognition of her work for developing a Global Positioning System (GPS) reinforcing system and improving Satellite Navigation technology.
A GPS reinforcing system provides real-time GPS location and integrity information within 1m ranges to enable the accurate and safe navigation of aircraft. However, when the sun reaches Solar Max, the amount of total electron increases rapidly in the ionosphere. This also increases the possibility of the position error of navigation using the GPS reinforcing system. In order to solve this problem, Professor Lee built an Ionosphere Danger model that monitors the changes in the ionosphere due to solar storm. The model has been implemented into original monitoring software that secures the safety of the GPS reinforcing system user. The research results were published in July 2012 in Radio Science, one of the most prestigious international journals in the field of geophysical studies.
The FAA Technical Center successfully verified Professor Lee’s software and the software is currently being distributed and used by major institutions around the globe, including Eurocontrol. It is expected that the software will be standardized after consultations with international organizations in the recent future.
Professor Lee said, “Satellite navigation is the core of future navigation technology. Since its utilization has been extended to aviation, marine, transportation, telecommunications, finance and other major national infrastructures, it is crucial to ensure the performance and reliability of the system … In the future, cooperation between nations will help to develop the worldwide service of the GPS reinforcing system.”
2013.10.12 View 8591 -
Therapy developed to induce Angiogenesis of Retina
- Junyeop Lee, Graduate School of Medical Sciences and Engineering
- Research results expected to be applied for treatment of diabetic retinopathy
A major clue to treatment of retinovascular disease, which causes blindness, has been found. The key to protection of the retinal nerve is the angiogenic protein that promotes healthy retinal vessel growth around the retina, which usually does not receive blood supply readily. This research offers a beginning to the possible improvement of therapy for diabetic retinopathy1 and retinopathy of prematurity2. Also important to the research is the fact that the ophthalmology specialist researcher, currently undergoing professional training, provided the results.
KAIST Graduate School of Medical Sciences and Engineering’s Junyeop Lee is the opthalmology specialist, who carried out the research under supervision by academic advisers Gyuyeong Go and Wookjun Yoo. The Ministry of Science, ICT and Future Planning as well as the National Research Foundation of Korea have funded his research. The research results have been published as a cover paper on ‘Science Translational Medicine’ on 18th August. This journal is a sister publication of Science, which is prestigious in the field of translational medicine that ties the basic science with clinical medicine. (Thesis title: Angiopoietin-1 Guides Directional Angiogenesis Through Integrin αvβ5 Signaling for Recovery of Ischemic Retinopathy)
The traditional treatment of diabetic retinopathy includes laser photocoagulation to destroy the retinal tissues or antibody therapeutics, which prevents vessel proliferation and blood leaking. The advantage of antibody therapeutics3 is that it retains the retinal nerves, however, it is not the fundamental solution but merely a temporary one, which requires repeated treatments.
The research team identified that Angiopoietin-14 protein, known as essential for growth and stabilization of vessels, also plays an important role in retinal vessel growth. The protein protects the retinal nerves, as well as provides improvement for retinal ischemia5 that is the root cause of vision loss due to retinal hemorrhages. It is expected to become a key to finding fundamental treatment method – by providing sufficient blood supply to the retina, thereby preserving the retinal nerve functions.
The results show that administration of Angiopoietin-1 to retinopathy mouse model promotes growth of healthy vessel growth, further preventing abnormal vessel growth, retinal hemorrhage and vision loss due to retinal ischemia.
Junyeop Lee said, “This research has identified that Angiopoietin-1 is an important factor in retinal vessel generation and stabilization. The paradigm will shift from traditional treatment method, which prevents vessel growth, to a new method that generates healthy vessels and strengthens vessel functions.”
1 Diabetic retinopathy: This retinovascular disease is a diabetic complication caused by insufficient blood supply. It is the major causes of blindness in adults.
2 Retinopathy of prematurity: The retinal vascular disease that occurs in premature infants with incomplete retinal vascular development. It is also the most common cause of blindness in children.
3 Antibody Therapeutics: Antibody developed to selectively inhibit abnormal blood vessel growth and leakage. Typical antibody therapeutics is Avastin and Lucentis, which hinder vascular endothelial growth factor (VEGF).
4 Angiopoietin-1: A critical growth factor that induces the production of healthy blood vessels and maintains the stability of the created vessel.
5 Retinal ischemia: State of ailment where retinal tissue blood supply is not sufficient.
Figure 1. Retinopathy mouse models show that, in comparison to the control group, the VEGF-Trap treatment and Angiopoietin-1 (Ang1) treatment groups significantly suppresses the pathological vascular proliferation. In addition, the Ang 1 group show vessel growth toward the central avascular area (region of retinal ischemia), which is not observed in VEGF-Trap treatment.
Figure 2. Reduced retinal ischemia, retinal bleeding and blood vessel normalization by Angiopoietin-1. Retinal ischemic region (arrow) and retinal bleeding significantly reduced in the Angiopoietin-1 (Ang1) treatment model in comparison to control group (left). The newly generated vessels in Ang 1 model are structurally supported by perivascular cells as normal retinal vessels do (right).
2013.10.12 View 10490 -
KAIST to establish Ombudsperson system
KAIST has recently undergone a massive reorganization to achieve a streamlined system and highly efficient administration; and it will now implement the new “Ombudsperson” system to hear the opinions of the members of the university.
On September 9th, President Sungmo Kang held a ceremony to appoint Professors Sang-Young Shin and Hong-Gu Shim as the new “Ombudspersons”.
The previous Shinmungo system raised complaints and recommendations for improvements by members of the university, but this is the first time that KAIST has assigned a direct department for handling such matters.
The newly appointed Ombudspersons will review for the possibility of any unjust, irrational systems, violations of research ethics and such. It is their role to take a neutral stance and advise on the correction and improvement.
The merit of the Ombudsperson system is that diverse opinions can be reflected on the policy. The Ombudsperson guarantees the security of the contents of discussion so that anyone can share his or her opinion without fear of being recorded in documents.
It is expected that the Ombudsperson system will protect the interests of the individuals and thus contribute to making a “happy campus”.
President [Sungmo] Kang has said that the reason establishing the office of the Ombudsperson is “In order for KAIST to take a new leap toward the world, it is crucial to bring the minds of the members together…. Even the smallest voices must be heard to present solutions to make the university where everyone’s happy.”
In 1809, the Swedish Parliament appointed the first “Ombudsperson” to investigate and resolve civil complaints. Now, it is widely used in public institutions, corporations and universities to improve the communication and work efficiency of the members.
The new Ombudsmen: Prof. Sang-Young Shin (left) and Prof. Hong-Gu Shim (right)
2013.09.27 View 9987 -
Jellyfish Exterminator Robot Developed
Formation Control demonstrated by JEROS
- Trial performance successfully completed with three assembly robots -
A team led by KAIST Civil and Environmental Engineering Department’s Professor Hyeon Myeong has just finished testing the cooperative assembly robot for jellyfish population control, named JEROS, in the field.
The rising number of accidents and financial losses by fishing industry, estimated at 300 billion won per year, caused by the recent swarm of jellyfish in coastal waters has been a major problem for many years. The research team led by Prof. Hyeon Myeong began developing an unmanned automated system capable of eradicating jellyfishin in 2009, and has since completed field-tests last year with success.
This year, JEROS’s performance and speed has been improved with the ability to work in formation as a cooperative group to efficiently exterminate jellyfish.
An unmanned aquatic robot JEROS with a mountable grinding part is buoyed by two cylindrical bodies that utilizes propulsion motors to move forward and reverse, as well as rotate 360 degrees. Furthermore, GIS (geographic information system)-based map data is used to specify the region for jellyfish extermination, which automatically calculates the path for the task. JEROS then navigates autonomously using a GPS (Global Positioning System) receiver and an INS(inertial navigation system).
The assembly robots maintain a set formation pattern, while calculating its course to perform jellyfish extermination. The advantage of this method is that there is no need for individual control of the robots. Only the leader robot requires the calculated path, and the other robots can simply follow in a formation by exchanging their location information via wireless communication (ZigBee method).
JEROS uses its propulsion speed to capture jellyfish into the grinding part on the bottom, which then suctions the jellyfish toward the propeller to be exterminated.
The field test results show that three assembly robots operating at 4 knots (7.2km/h) disposes jellyfish at the rate of about 900kg/h.
The research team has currently completed testing JEROS at Gyeongnam Masan Bay and is expected to further experiment and improve the performance at various environment and conditions.
JEROS may also be utilized for other purposes including marine patrols, prevention of oil spills and waste removal in the sea.
JEROS research has been funded by Ministry of Science, ICT and Future Planning and Ministry of Trade, Industry and Energy.
2013.09.27 View 16201 -
Transparent Glass Wall as a Touch Game Media
Professor Woo-hoon Lee
- Selected as the “Highlight” at SIGGRAPH emerging technology conference
- “An excellent example of the transparent display panel in everyday life”
A joint research team led by KAIST Industrial Design Department’s Prof. Woo-hoon Lee and Computer Sciences Prof. Ki-hyuk Lee has developed a brand new concept game media “TransWall”, which utilizes both sides of the glass wall as the touch medium.
TransWall has been chosen as the “highlight” of 2013 SIGGRAPH emerging technology conference. SIGGRAPH is a world-renowned conference in the area of computer graphics and interaction technique, last held 21st-25th July at Anaheim, in the United States.
It all started with the thought, wouldn’t it be possible to turn the glass walls surrounding us into a medium for entertainment and communication?
TransWall utilizes holographic screen film inserted between two glass sheets with a multi-touch function, onto which the image can be projected using the beam projector from both sides. Furthermore, an additional Surface Transducer attached to the glass can deliver the sound and vibration.
What seemed as an ordinary glass wall has been transformed into a multi-sensory media that can transmit and receive visual, auditory and tactile information.
TransWall can be implemented at public places such as theme parks, large shopping malls and subway stations, providing the citizens with a new form of entertainment. This touch-interaction method can also be applied to developing a variety of cultural contents in the future.
Professor Lee said, “TransWall shows an example of near-future where touch-interaction method can be utilized with the soon-to-be commercialized transparent display panel in everyday lives.”
TransWall Introduction video (https://vimeo.com/70391422)
TransWall at SIGGRAPH 2013 Display (https://vimeo.com/71718874)
Picture 1. Both sides of the glass wall can be used as a touch platform for various medias, including games.
Picture 2. TransWall attracts the interests of the audience at SIGGRAPH emerging technology.
Picture 3. Structure of TransWall
Picture 4. Photo of TransWall from side
2013.09.19 View 8901 -
Professor Kwang-Hyun Cho publishes Encyclopaedia of Systems Biology
Professor Kwang-Hyun Cho
KAIST Biological and Brain Engineering Department’s Professor Kwang-Hyun Cho edited the Encyclopaedia of Systems Biology with three scholars, all experts of Systems Biology in England, Germany and the United States. It is rare that a Korean scientist edits a world renowned academic science encyclopaedia.
The Encyclopaedia, published by the New York office of Springer Verlag, was a grand international project five years in the making by 28 editors and 391 scientists with expertise in Systems Biology from around the world. The Encyclopaedia compiles various research areas of Systems Biology, the new academic paradigm of the 21st century through the integration of IT and BT, comprehensively on 3,000 pages in 4 four volumes.
Professor Kwang-Hyun Cho, who led this international project, majored in electrical engineering and pioneered the field of Systems Biology, the integrated study of biological sciences and engineering, as a new integrated field of IT since the 1990s. The professor has achieved various innovative research results since then. Recently he has investigated “kernel,” an evolutionary core structure in complex biological networks and developed a new cancer treatment through the state space analysis of the molecular network of cancer cells. His work was published in Science Signalling, a sister journal of Science, as a cover story several times, and contributed to foundational research as well as commercialisation of the integrated fields of IT and BT.
2013.08.27 View 8772 -
Secondary, High Capacity Battery developed from Rice Husks
Rice husks, a waste product from rice polishing, has been successfully utilized as the silicon anode for use in high capacity lithium ion secondary batteries. The new silicon anode derived from rice husks exhibit superior output and lifespan.
Professor Choi Jang Wook (The Graduate School of Energy, Environment, Water and Sustainability (EEWS)) and Professor Park Seung Min (Department of Biochemistry) and their respective research teams separated naturally occurring, highly porous silica material within the rice husks and developed a 3-dimensional, highly porous silicon anode material.
The result of the research effort was published in the online edition of the Proceedings of the National Academy of Sciences (PNAS) journal, a world renowned journal in the field of natural sciences.
Silicon has attracted much attention as anode material for next generation lithium ion secondary batteries because it exhibits 3~5 times higher capacity than conventional graphene. The high capacity will pave the way to lithium secondary batteries with higher energy densities than conventional batteries. It is anticipated that the application of silicon batteries will yield electronic devices with a longer duration for use in addition to electronic vehicles boasting longer mileage.
The silicon anode is based on the 3-dimensional, highly porous structure of rice husks which remedies the problematic extreme volume expansion of conventional silicon anodes.
Utilization of inexpensive rice husks to create high value silicon anodes will cause a ripple effect on the industry and academia.
2013.08.23 View 9711 -
Short Wavelength, Ultra-High Speed Quantum Light Source based on Quantum Dot Developed
Professor Yong Hoon, Cho (Department of Physics) and his research team synthesized an obelisk nanostructure and successfully formed a single semiconductor quantum exhibiting high reliability to realize an ultra-high speed, highly efficient, release of quantum dots.
The result of the research effort was published in the July 5th online edition of Scientific Reports published by Nature.
Semiconductor Quantum Dots restrict electrons within a cubic boundary of few nanometers thereby exhibiting similar properties to an atom with discontinuous energy levels. Exploitation of this characteristic makes possible the development of quantum light source, critical for next generation quantum information communication and quantum encryption.
High operational temperatures, stability, rapid photon release, electric current capability, and other advantages are reasons why semiconductor quantum dots are regarded as next generation core technology.
However conventional, spontaneously formed quantum dots are densely packed in a planar structure rendering the analysis of a single quantum dot difficult and result in the poor efficiency of photon release. In addition, the internal electromagnetic effect which is caused by inter-planar stress results in low internal quantum efficiency due to the difficulty in electron-hole recombination.
Professor Cho’s research team synthesized an obelisk shaped nanostructure using nitrides that emit short wavelengths of light. The activation layer was grown on the tip of the nanostructure and the team succeeded in placing a single quantum dot on the nano-tip. The team was therefore able to confirm the ultra-high speed single photon characteristics which occur at low energy levels.
Use of unique nanostructures makes synthesis of single atomic structures without processes like patterning while enabling the release of light emitted by the quantum dot.
Using this unique method the team showed the increase in internal quantum efficiency. The electromagnetic forces apparent in thin films no longer affects the quantum dot greatly due to the obelisk structure’s reduced inter planar stress.
The newly developed quantum light source emits visible light (400nm range) and not the conventional infrared light. This characteristic makes possible it use in communication in free space and enables use of highly efficient, visible range photon detector.
Professor Cho commented that “the developed method makes quantum dot growth much easier making single photon synthesis much faster to contribute to the development of practical quantum light source.” And that “the characteristics of the obelisk nanostructure enable the easy detachment from and attachment to other substrates enabling its use in producing single chip quantum light source.”
The research was conducted under the supervision of Professor Cho. The researchers werey Jae Hyung, Kim (first author) and Yong Ho, Ko (second author), both Ph.D. candidates at KAIST. The Ministry of Science, ICT and Future Planning, the National Research Foundation, and WCU Program provided support to the research effort.
2013.08.23 View 7962
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Ultra-High Strength Metamaterial Developed Using Graphene
New metamaterial has been developed, exhibiting hundreds of times greater strength than pure metals.
Professor Seung Min, Han and Yoo Sung, Jeong (Graduate School of Energy, Environment, Water, and Sustainability (EEWS)) and Professor Seok Woo, Jeon (Department of Material Science and Engineering) have developed a composite nanomaterial. The nanomaterial consists of graphene inserted in copper and nickel and exhibits strengths 500 times and 180 times, respectively, greater than that of pure metals. The result of the research was published on the July 2nd online edition in Nature Communications journal.
Graphene displays strengths 200 times greater than that of steel, is stretchable, and is flexible. The U.S. Army Armaments Research, Development and Engineering Center developed a graphene-metal nanomaterial but failed to drastically improve the strength of the material.
To maximize the strength increased by the addition of graphene, the KAIST research team created a layered structure of metal and graphene. Using CVD (Chemical Vapor Deposition), the team grew a single layer of graphene on a metal deposited substrate and then deposited another metal layer. They repeated this process to produce a metal-graphene multilayer composite material, utilizing a single layer of graphene. Micro-compression tests within Transmission Electronic Microscope and Molecular Dynamics simulations effectively showed the strength enhancing effect and the dislocation movement in grain boundaries of graphene on an atomic level.
The mechanical characteristics of the graphene layer within the metal-graphene composite material successfully blocked the dislocations and cracks from external damage from traveling inwards. Therefore the composite material displayed strength beyond conventional metal-metal multilayer materials. The copper-graphene multilayer material with an interplanar distance of 70nm exhibited 500 times greater (1.5GPa) strength than pure copper. Nickel-graphene multilayer material with an interplanar distance of 100nm showed 180 times greater (4.0GPa) strength than pure nickel.
It was found that there is a clear relationship between the interplanar distance and the strength of the multilayer material. A smaller interplanar distance made the dislocation movement more difficult and therefore increased the strength of the material. Professor Han, who led the research, commented, “the result is astounding as 0.00004% in weight of graphene increased the strength of the materials by hundreds of times” and “improvements based on this success, especially mass production with roll-to-roll process or metal sintering process in the production of ultra-high strength, lightweight parts for automobile and spacecraft, may become possible.” In addition, Professor Han mentioned that “the new material can be applied to coating materials for nuclear reactor construction or other structural materials requiring high reliability.”
The research project received support from National Research Foundation, Global Frontier Program, KAIST EEWS-KINC Program and KISTI Supercomputer and was a collaborative effort with KISTI (Korea Institute of Science and Technology Information), KBSI (Korea Basic Science Institute), Stanford University, and Columbia University.
A schematic diagram shows the structure of metal-graphene multi-layers. The metal-graphene multi-layered composite materials, containing a single-layered graphene, block the dislocation movement of graphene layers, resulting in a greater strength in the materials.
2013.08.23 View 14256 -
Ultra High Speed Nanomaterial Synthesis Process Developed Using Laser
Dr. Jun-Yeop, Yeo and the research team led by Professor Seung-Hwan, Ko (both of the Department of Mechanical Engineering) successfully developed a process enabling the location-determinable, ultra high speed synthesis of nanomaterials using concentrated laser beams.
The result of the research effort was published as the frontispiece in the July 9th issue of Advanced Functional Materials, a world renowned material science and engineering academic journal.
Application of the technology reduced the time needed to process nanomaterial synthesis from a few hours to a mere five minutes. In addition, unlike conventional nanomaterial synthesis processes, it is simple enough to enable mass production and commercialization.
Conventional processes require the high temperatures of 900~1,000 °C and the use of toxic or explosive vapors. Complex processes such as separation after synthesis and patterning are needed for application in electronic devices. The multi-step, expensive, environmentally unfriendly characteristics of nanomaterial synthesis served as road blocks to its mass production and commercialization.
Exposing the precursor to concentrated continuous laser beam (green wavelength) resulted in the synthesis of nanowires in the desired location; the first instance in the world to accomplish this feat. The technology, according to the research team, makes possible the production, integration and patterning of nanomaterials using a single process. Applicable to various surfaces and substrates, nanowires have been successfully synthesized on flexible plastic substrates and controlled patterning on the surface of 3-dimensional structures.
Dr. Yeo commented that the research effort has “yielded the creation of a nanomaterial synthesis process capable of synthesis, integration, pattern, and material production using light energy” and has “reduced the synthesis process time of nanomaterial to one tenths of the conventional process.” Dr. Yeo continues to devise steps to commercialize the new multifunctional electronic material and methods for mass production.
The research effort, led by Dr. Yeo and Professor Ko, received contribution from Professor Hyung-Jin Sung (KAIST Department of Mechanical Engineering), Seok-Joon Hong, a Ph.D. candidate, Hyun-Wook Kang, also a Ph.D. candidate, Professor Costas Grigoropoulos of UC Berkeley, and Dr. Dae Ho Lee. In addition, the team received support from the National Research Foundation, Ministry of Knowledge Economy, Global Frontier Program, and KAIST EEWS.
Picture I: Synthesized nanomaterials produced at a desirable location by laser beams
Picture 2: Synthesized nanomaterials built on the 3D structure by using the developed technology
Picture 3: Functional electric circuit made with synthesized nanomaterials
Picture 4: Cover page of July 9th issue of Advanced Functional Materials
2013.08.23 View 9405 -
KAIST unveils foldable micro electric car, Armadillo-T
The small and light electric car completely folds in half when parking, making it a perfect fit for public or private transportation in an urban environment.
Looking for a parking space for hours at a busy shopping mall or being stuck on roads jammed with cars releasing large amounts of carbon dioxide are all-too-familiar scenes for city dwellers.
A group of researchers at the Korea Advanced Institute of Science and Technology (KAIST) recently developed a possible solution to such problems: a foldable, compact electric vehicle that can be utilized either as a personal car or part of the public transit system to connect major transportation routes within a city.
In-Soo Suh, associate professor of the Graduate School for Green Transportation at KAIST, and his research team introduced a prototype micro electric car called "Armadillo-T," whose design is based on a native animal of South America, the armadillo, a placental mammal with a leathery armor shell.
The research team imitated the animal"s distinctive protection characteristic of rolling up into a ball when facing with threat from predators. Just as armadillos hide themselves inside the shell, Armadillo-T tucks its rear body away, shrinking its original size of 2.8 meters (110 inches) down to almost half, 1.65 meters (65 inches), when folding.
Armadillo-T is a four-wheel-drive, all-electric car with two seats and four in-wheel motors. Since the motors are installed inside the wheels, and the 13.6 kWh capacity of lithium-ion battery pack is housed on the front side, the battery and motors do not have to change their positions when the car folds. This not only optimizes the energy efficiency but also provides stability and ample room to drivers and passengers.
Once folded, the small and light (weighs 450 kg) electric vehicle takes up only one-third of a 5-meter parking space, the standard parking size in Korea, allowing three of its kind to be parked. With a smartphone-interfaced remote control on the wheels, the vehicle can turn 360 degrees, enhancing drivers" convenience to park the car, even in an odd space in a parking lot, the corner of a building, for example.
Professor In-Soo Suh said, "I expect that people living in cities will eventually shift their preferences from bulky, petro-engine cars to smaller and lighter electric cars. Armadillo-T can be one of the alternatives city drivers can opt for. Particularly, this car is ideal for urban travels, including car-sharing and transit transfer, to offer major transportation links in a city. In addition to the urban application, local near-distance travels such as tourist zones or large buildings can be another example of application."
The concept car has loads of smart features on board, too: the cameras installed inside the car eliminate the need for side mirrors and increase the driver"s ability to see the car"s right and left side, thereby reducing blind spots. With a smartphone, the driver can control Armadillo-T and enable remote folding control. The car has a maximum speed of 60 km/h, and with a ten-minute fast charge, it can run up to 100 km.
Professor Suh explained that the concept of Armadillo-T was originally initiated in 2011 as he focused his research interest on the sub-A segment of personal mobility vehicles (PMVs), which are smaller and lighter than the current compact cars, as a new personalized transport mode.
"In coming years, we will see more mega-size cities established and face more serious environmental problems. Throughout the world, the aging population is rapidly growing as well. To cope with climate, energy, and limited petroleum resources, we really need to think outside the box, once again, to find more convenient and eco-friendly transportation, just as the Ford Model T did in the early 1920s. A further level of R&D, technical standards, and regulatory reviews are required to have these types of micro vehicles or PMVs on the market through test-bed evaluations, but we believe that Armadillo-T is an icon toward the future transport system with technology innovation."
The research project has been supported by the Korean government, the Ministry of Land, Infrastructure and Transport and the Korea Agency for Infrastructure Technology Advancement, since December 2012.Youtube Link: http://www.youtube.com/watch?v=8DoZH7Y-sR0
2013.08.21 View 13956 -
Two Dimensions of Value: Dopamine Neurons Represent Reward but not Aversiveness
Professor Christopher D. Fiorillo of the Bio & Brain Engineering (http://ineuron.kaist.ac.kr/web/home.html) at KAIST published a research paper in the August 2 issue of Science. The title of the paper is “Two Dimensions of Value: Dopamine Neurons Represent Reward but not Aversiveness.” The following is an introduction of his research work:
To make decisions, we need to estimate the value of sensory stimuli and motor actions, their “goodness” and “badness.” We can imagine that good and bad are two ends of a single continuum, or dimension, of value. This would be analogous to the single dimension of light intensity, which ranges from dark on one end to bright light on the other, with many shades of gray in between. Past models of behavior and learning have been based on a single continuum of value, and it has been proposed that a particular group of neurons (brain cells) that use dopamine as a neurotransmitter (chemical messenger) represent the single dimension of value, signaling both good and bad.
The experiments reported here show that dopamine neurons are sensitive to the value of reward but not punishment (like the aversiveness of a bitter taste). This demonstrates that reward and aversiveness are represented as two discrete dimensions (or categories) in the brain. “Reward” refers to the category of good things (food, water, sex, money, etc.), and “punishment” to the category of bad things (stimuli associated with harm to the body and that cause pain or other unpleasant sensations or emotions).
Rather than having one neurotransmitter (dopamine) to represent a single dimension of value, the present results imply the existence of four neurotransmitters to represent two dimensions of value. Dopamine signals evidence for reward (“gains”) and some other neurotransmitter presumably signals evidence against reward (“losses”). Likewise, there should be a neurotransmitter for evidence of danger and another for evidence of safety. It is interesting that there are three other neurotransmitters that are analogous to dopamine in many respects (serotonin, norepinephrine, and acetylcholine), and it is possible that they could represent the other three value signals.
For the research article, please visit: http://www.sciencemag.org/content/341/6145/546.abstract
For the Science 2nd issue, please visit: http://www.sciencemag.org/content/current#ResearchArticles
Illustration of Value Dimension
2013.08.08 View 7489