Brain Bits, 3/28/15

lightning brain2

credit: A. Ajifo

Welcome to Brain Bits, where I highlight important or interesting recent news in the world of neuroscience. In store for today: wireless brain stimulation, implanting false memories during sleep, and a new technology for mutating an entire species (seriously!).

 

A new Science paper demonstrates how a recently developed DNA engineering technique called CRISPR can be used to generate self-propagating mutations. Mutated genes usually spread slowly throughout a species because they have to compete with the normal version of the gene. But this new type of mutation automatically replaces all normal copies of the gene with the mutated version, allowing you to mutate an entire species! This has enormous implications. We might be able to solve huge public health problems, like making all mosquitoes resistant to malaria so they couldn’t spread the disease. But with great power comes great responsibility: this technology carries the risk of accidentally mutating—and potentially eradicating—a whole species. Some neuroscientists even believe that publishing this study was “a step too far”. While I agree that the technology carries significant risks that must be considered, I share the view of the study’s lead author, Ethan Bier: “Nothing is served by hiding things. The whole point is to show that it is possible and have a public discussion.”

A cool new study in Nature Neuroscience implanted false memories into mice while they were sleeping. The hippocampus, which is important for learning, contains neurons that fire when you’re in a particular place, called “place cells”. These cells are also activated during sleep, which is thought to reflect your memory of the places you’ve visited during the day. In this study, researchers waited for a specific place cell (corresponding with a specific place) to spontaneously fire in a sleeping mouse, then stimulated a reward area of the brain at the same time. This created a false memory of that particular place being associated with reward—the next day, the mouse went straight to the place (and was probably disappointed there was nothing there!). This study demonstrates not only that it’s possible to manipulate memory during sleep, but also that place cell activity is causally important for spatial navigation and memory, which had been long-hypothesized but never confirmed. Non-technical summary here.

Deep-brain stimulation has been used to improve symptoms of several neurological conditions, most notably Parkinson’s disease. However, this requires sticking electrodes into the patient’s brain, which is highly invasive. A new Science paper describes a novel technique for non-invasively achieving deep-brain stimulation in mice using a magnetic field. This method does require injecting magnetic nanoparticles as well as a heat-sensitive channel into the brain; the magnetic field then heats up the nanoparticles to activate the channel, which activates the neurons. Once the injections are completed, you can stimulate specific brain areas remotely. Currently this technique mainly seems useful for studying brain function in animal models, but hopefully it will eventually be translated into a new therapy for human brain disorders.

A report on the European Human Brain Project—a massive, well-funded project analogous to the Brain Initiative in the U.S.—has concluded that the project is mismanaged and misguided. The independent investigation and resulting report were precipitated by a strong backlash last year by hundreds of neuroscientists who signed an open letter arguing that the project is not “well conceived or implemented”. Much of the criticism targets the project’s goal of simulating the entire human brain on a supercomputer, which many scientists consider unrealistic. The new report recommends focusing on more realistic goals, such as technology development. I truly hope the project’s leaders will change course and are able to regain the trust of the neuroscience community and the public, since projects like these have huge potential in advancing brain research.

My home state of Missouri made news by executing a convicted murderer who was missing a large chunk of his frontal lobe, the part of the brain that helps us make decisions and control our impulses. Cecil Clayton had previously lost about 20% of his frontal lobe in an accident, which immediately changed his personality, diminished his cognitive abilities, and induced hallucinations. Many argue that it’s wrong to execute those who are mentally incapacitated, especially if their disabilities are clearly rooted in a brain abnormality. Whether or not you agree, this case draws attention to the growing field of “neurolaw”—how neuroscience should be applied to the legal system. This issue has been pondered in some interesting articles (here and here) and in a great Radiolab episode.

Did you see any recent neuroscience news that you’d like to share? Leave a comment below!


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