New tools and techniques in science don’t usually garner as much publicity as big discoveries, but there is a sense in which they are much more important. Think of telescopes and microscopes: both opened vast fields of endeavour that are still spawning thousands of major advances. And although they may not make newspaper front pages, new tools are often the biggest news in scientists' own ratings—published in prestigious journals and staying at the top of citation indices for years on end. Clever tools are the really long-lasting news behind the news, driving science forward for decades.
One neat example has just come along, which I really like. A new technique makes it possible to see directly the very fast electrical activity occurring within the nerve cells of the brain of a living, behaving animal. Neuroscientists have had something like this on their wish list for years and it’s worth celebrating. The technique puts into nerve cells a special protein that can turn the tiny voltage changes of nerve activity into flashes of light. These can be seen with a microscope and recorded in exquisite detail, providing a direct window into the activity of a brain and the fine dynamics of signals travelling through nerves. That is especially important because the hot news is that information contained in the nerve pulses speeding around the brain is likely coded, not just in the rate at which those pulses arrive but also their timing, with the two working at different resolutions. To start to speak neuron and thus understand our brains, we are going to have to get to grips with the dynamics of signalling and relate it to what an animal is actually doing.
The new technique, developed by Yiyang Gong and colleagues in Mark Schintzer’s lab at Stanford University, and published in the journal Science, builds on past tools for imaging nerve impulses. One well-established method takes advantage of the calcium ions which rush into a nerve cell as a signal speeds by. Special chemicals that give off light when they interact with calcium make that electrical activity visible, but they're not fast or sensitive enough to capture the speed with which the brain works. The new technique goes further by using a rhodopsin protein (called Ace), which is very sensitive to voltage changes in the nerve cell membrane, fused to another protein (mNeon), which can fluoresce very brightly. The combination is both fast and bright.
This imaging technique will take its place alongside other recent developments that extend the neuroscientist’s reach. New optogenetic tools are truly stunning; they enable researchers to use light signals to switch particular nerve cells off and on to help figure out what part they play in a larger circuit.
Without constantly inventing new ways to probe the brain, the eventual goal of understanding how our 90 billion nerve cells provide us with thought and feeling will be utterly intractable. Although we have some good insights into our cognitive strategies from psychology, deep understanding of how individual neurons work and rapidly growing maps of brain circuitry, the vital territory in the middle—how circuits of particular linked neurons work—is very tough to explore. To make progress, neuroscientists' dream of experiments where they can record what is happening in many nerves in a circuit, while also switching parts of the circuit off and on, and seeing the impact on a living animal’s behavior. Thanks to new tools, this remarkable dream is coming close, and when the breakthroughs arrive, the toolmakers will once again have proved that in science, it is new tools that create new ideas.