Controlling the Brain with Light

With a technique called optogenetics, researchers can probe how the nervous system works in unprecedented

Image: Photograph by Darren Braun

detail. Their findings could lead to better treatments for psychiatric problems.

Every day as a practicing psychiatrist, I confront my field’s limitations. Despite the noble efforts of clinicians and researchers, our limited insight into the roots of psychiatric disease hinders the search for cures and contributes to the stigmatization of this enormous problem, the leading cause worldwide of years lost to death or disability. Clearly, we need new answers in psychiatry. But as philosopher of science Karl Popper might have said, before we can find the answers, we need the power to ask new questions. In other words, we need new technology.

Developing appropriate techniques is difficult, however, because the mammalian brain is beyond compare in its complexity. It is an intricate system in which tens of billions of intertwined neurons—with multitudinous distinct characteristics and wiring patterns—exchange precisely timed, millisecond-scale electrical signals and a rich diversity of biochemical messengers.

Because of that complexity, neuroscientists lack a deep grasp of what the brain is really doing—of how specific activity patterns within specific brain cells ultimately give rise to thoughts, memories, sensations and feelings. By extension, we also do not know how the brain’s physical failures produce distinct psychiatric disorders such as depression or schizophrenia. The ruling paradigm of psychiatric disorders—casting them in terms of chemical imbalances and altered levels of neurotransmitters—does not do justice to the brain’s high-speed electrical neural circuitry. Psychiatric treatments are thus essentially serendipitous: helpful for many but rarely illuminating.

In Brief

  • Neuroscientists have long been frustrated by their inability to study how the brain works in sufficiently precise detail. Unexpectedly, a solution has emerged from basic genetic research on micro­organisms that rely on light-responsive “opsin” proteins to survive.
  • By inserting opsin genes into the cells of the brain, scientists can now use flashes of light to trigger firing by specific neurons on command. This technology, optogenetics, permits researchers to conduct extremely precise, cell type–targeted experiments in the brains of living, freely moving animals—which electrodes and other traditional methods do not allow.
  • Although optogenetics is still in its infancy, it is already yielding potentially useful insights into the neuroscience underlying some psychiatric conditions.

Source: Scientific American magazine

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Mapping the Mind

Mapping the Mind: Online Interactive Atlas Shows Activity of 20,00

0 Brain-Related Genes

Scientists have long sought to understand the biological basis of thought. In the second century A.D., physician and philosopher Claudius Galen held that the brain was a gland that secreted fluids to the body via the nerves—a view that went unchallenged for centuries. In the late 1800s clinical researchers tied specific brain areas to dedicated functions by correlating anatomical abnormalities in the brain after death with behavioral or cognitive impairments. French surgeon Pierre Paul Broca, for example, found that a region on the brain’s left side controls speech. In the first half of the 20th century, neurosurgeon Wilder Penfield mapped the brain’s functions by electrically stimulating different places in conscious patients during neurosurgery, triggering vivid memories, localized body sensations, or movement of an arm or toe.

In recent years new noninvasive ways of viewing the human brain in action have helped neuroscientists trace the anatomy of thought and behavior. Using functional magnetic resonance imaging, for instance, researchers can see which areas of the brain “light up” when people perform simple movements such as lifting a finger or more complex mental leaps such as recognizing someone or making a moral judgment. These images reveal not only how the brain is divided functionally but also how the different areas work together while people go about their daily activities. Some investigators are using the technology in an attempt to detect lies and even to predict what kinds of items people will buy; others are seeking to understand the brain alterations that occur in disorders such as depression, schizophrenia, autism and dementia.

Source: Scientific American magazine

Open-source personal robotics seeks a community to make it affordable

PR2

Until someone develops a common platform for building robots (think of the combination of Windows and Intel that has made PCs so accessible), the technology will remain elusive to the general public. At least that’s the contention of Willow Garage, Inc., a Menlo Park, Calif. company that Wednesday made its PR2 personal robot available to the public.

PR2 comes with the basics: a mobile base, two arms for manipulation, a suite of sensors and two computers, each with eight processing cores, 24 gigabytes of RAM and two terabytes of hard disk . Willow Garage is hoping that its robot will blossom with the help of an open community of devoted engineers and software developers that can build on the PR2’s basics and share their breakthroughs with each other. Call it open source for                                                                                                                robots.

The field of robotics needs to become more standardized if it is to flourish, says Keenan Wyrobek, co-director of Willow Garage’s Personal Robotics Program. “PR2 is all about taking us from where we are today to where you can pretty much make your own robot as needed,” he says.

The PR2 comes with a robot operating system (ROS), which handles the robot’s computation and hardware manipulation functions, to name a few. The ROS, like open-source software, is free and can be tweaked by users, as long as any improvements are shared back with the rest of the community of PR2 and ROS users. This community is key to the PR2’s success because it opens up the project to ideas and input from engineers around the world who know how to write programs for robotics navigation, vision, movement and other functions.

In terms of hardware, the PR2 is less open-source and more modular, with arms, grippers, sensors and other interchangeable parts that can be improved upon by the robots’ users. Wyrobek hopes that an independent industry will form to develop hardware improvements and extensions to the PR2, much the way companies sell software and peripherals for PCs.

Through the ongoing creation of standardized components, this community is expected also to play a role in lowering the PR2’s $400,000 price tag over time. A parallel would be the way PC makers were able to dramatically lower prices by standardizing on the so-called “Wintel” platform, which is the Microsoft Windows operating system running on computer powered by Intel processors. In the meantime, Willow Garage is offering discounted PR2s (at $280,000) to people who have made significant contributions to the open source community by writing and releasing code and other resources. “When evaluating an application, we will look at the code you have made available in a public repository, as well as accompanying documentation and tutorials,” according to the company’s Web site. “We will also look to see if other people are using your code. Finally, we will consider your ability to release as open source the code you would produce with the PR2.” There is no cap on the number of discounted PR2s the company will offer.

Willow Garage probed the market in advance of its official launch with a beta-testing program, through which the company distributed 11 robots to teams of engineers willing to experiment with the robot’s basic functions. It was the beginning of a community that Wyrobek hopes will exchange ideas for improving the technology with each other and with his company. “It’s sort of greasing the wheels,” he admits. PR2 owners contribute the ideas and applications to ROS.org, a Web site dedicated to the robot’s budding community.

One beta tester, Georgia Tech in Atlanta, is tweaking the personal robot so that it can help senior citizens. The school’s Healthcare Robotics Lab is developing software for PR2s named Cody and EL-E so that they can open doors and drawers and flip light switches guided by a laser pointer, radio signals or touch.

The Bosch Research and Technology Center in Palo Alto, Calif., part of electronics and appliances maker The Bosch Group, has begun a two-year project to integrate its advanced sensor technology—including micro electro-mechanical system (MEMS) accelerometers, gyros and force sensors, and air pressure sensors—to improve the PR2’s performance and reliability. Other beta testing sites include Stanford University and the Massachusetts Institute of Technology (M.I.T.).

Source: Scientific American Magazine

Flash in the Can? More Powerful Next-Gen Memory Chips Wait in the Wings

The memristorProcessor chips are the brains of today’s consumer digital devices, but memory is actually at their heart, with flash memory being the favored approach for cards that plug into mobile phones, cameras and PCs. Whereas hard drives store large amounts of long-term data, RAM—also called “solid state” memory—retains information outside the hard drive, where it can be accessed quickly and repeatedly. Flash memory, the cheapest RAM variety at only about $1.50 per gigabyte (after that is dynamic RAM, or DRAM, more than a dozen times more expensive), does not require much power and can retain data after a device is powered down, key to gadget-makers ability to turn out smaller, more powerful devices.

But flash has its limitations and will someday reach a scaling barrier that would leave subsequent generations of digital cameras and cell phones unable to store significantly more information or operate orders of magnitude faster than their predecessors—at least not without costing a lot more. “What it comes down to is that we’ve gotten spoiled with our gadgets,” says Stan Williams, Hewlett–Packard senior fellow and founding director of HP’s Information and Quantum Systems Lab. “We’ve come to expect exponentially faster devices, but technologies like flash are getting toward the end of their ability to scale.”

Flash is also less durable than static RAM (SRAM) or DRAM, wearing out and becoming less reliable over time. SRAM, which costs about $450 per gigabyte, is often used for cache memory in microprocessors and can rapidly read and write data.

For these reasons HP, IBM and others are grooming new technologies to be the replacement for flash as soon as these limitations catch up to the demands of manufacturers and consumers.

A smarter type of memory
A recently announced alliance between HP and Hynix Semiconductor aims to fill the imminent gap with a denser and more energy-efficient technology called resistive random access memory (RRAM) that could roll off the assembly line in the next few years.

RRAM technology (sometimes called ReRAM) is in a relatively early stage of development but has managed to garner attention from HP, Sharp, Samsung and several other companies that have received RRAM-related patents in the past decade.

The key component of HP’s RRAM, so named because data flows with the help of changes in electrical resistance, is a switch called a memristor (or memory resistor). In addition to holding nonvolatile memory (it can retain information even when off), HP says a memristor can also perform computations, a feature that other types of RAM do not have. This versatility gives the company hope that it will someday be able to replace memory and central processing units (CPUs) with a single chip that performs both functions.

Although scientists have known about memristor dynamics for about 40 years, only recently have they been able to design the technology into integrated circuits, Williams says. RRAM involves a subtle motion of atoms, changing the film of a resistor by a matter of nanometers. “People have been talking about this for 40 years but weren’t able to fully understand or control the process,” Williams says.

Whereas a one-bit flash memory can be switched on and off hundreds of thousands of times (a switch might involve taking or deleting a picture on a digital camera), a memristor has a much longer lifespan than flash, Williams says. On the memory sticks and digital cameras where flash has flourished, switching is not done in the same volume as in other types of memory, so flash can get away with its lower level of endurance, he says.

In April, HP Labs announced its discovery that a memristor could also perform logic, enabling computation to one day be performed in chips where data is stored, rather than on a specialized CPU. HP researchers also say they have designed an architecture where multiple layers of memristor memory can be stacked on top of one another in a single chip to increase storage capacity without taking up much more space.

Although much of RRAM and memristor’s future is speculative, HP has no shortage of plans for the technology. The company’s goal is to develop and commercialize a RRAM chip in roughly three years that is faster and more durable than flash yet uses less power and features twice the number of bits for storage, Williams says. “We would redesign products around memristor technology,” he adds. HP’s long-term play is for RRAM to compete with flash, DRAM and even hard disks.

Competing with DRAM, however, requires much greater endurance. A DRAM used by a supercomputer doing climate modeling might read or erase data one quintillion (one million trillion) times over the course of three or four years, Williams says. “That’s daunting, but that’s what we’re going to have to do to compete head-to-head with DRAM,” he adds.

For all of their excitement over memristors HP still faces a number of challenges in bringing its RRAM to market. For one, “HP’s memristor is made using a titanium oxide, which is not common to put on semiconductors and appears to be difficult to manage today,” says Jim Handy, an analyst with the semiconductor market research firm Objective Analysis in Los Gatos, Calif. HP disputes this characterization of titanium oxide, saying there are established protocols for applying it to semiconductor material and that titanium oxide is compatible with current complementary metal-oxide-semiconductor (CMOS) technology used to build integrated circuits.

Source: Scientific American Magazine