Closed-Loop Neuroscience and Neuroengineering

Feedback and closed-loop circuits exist in just about every part of the nervous system. It is curious, therefore, that for decades neuroscientists have been probing the nervous system in an open-loop manner to understand it. Instead of the linear, reductionistic “stimulate ？ record response” approach, a more modern approach is taking hold: closed-loop neuroscience. It respects the inherent “loopiness” of neural circuits, and the fact that the nervous system is embodied, and embedded in an environment. Through active sensing, behaving animals can influence their environment in ways that alter subsequent sensory inputs. Therefore, loops abound not only in the nervous system itself, but through its dynamic interactions with the world. By interposing our own technology in some of these loops, we can achieve unprecedented control over the system being studied and explore the functional consequences. This Research Topic, “Closing the Loop Around Neural Systems,” presents a diverse set of recent methodological, scientific and theoretical advances from neuroscientists and neuroengineers who are pioneering closed-loop neuroscience. As shown here, cutting-edge researchers are taking advantage of real-time or “on-line” processing of large streams of neural data. This has become feasible thanks to advances in computer processing power, in electronics such as microprocessors and field-programmable gate arrays (FPGAs), and in specialized and open-source software. These advances have enabled a wide variety of new neuroscience approaches to understanding, modulating, and interfacing with the nervous system – approaches in which the variables being monitored can influence the experiment in progress, just as active sensing can influence an animal’s next input. Our call for submissions to this Frontiers in Neural Circuits Research Topic yielded an overwhelming response, indicating that closing the loop around neural systems is an exciting and rapidly expanding field. Perhaps this is because of the diversity of ways in which “closed-loops” can be interpreted and implemented (Fig. 1). This Research Topic presents seven Methods articles, 16 Original Research articles, and seven Reviews, Mini-Reviews, and Perspectives, for a total of 30 accepted papers published in Frontiers in Neural Circuits between April 2012 and October 2013. A map showing the locations of all the contributors reveals that most are in the USA and Europe, although researchers in Russia, Japan, and Israel are also represented. Several articles describe or review new technologies that increase the options