After many years of steady but seemingly slow progress, the development and use of light-based methods for investigating the function of the brain is really accelerating. Part of this is undoubtedly due to the excitement surrounding the use of light-activated channels for neuronal stimulation. This has been highlighted as one of our “”https://www.nature.com/nmeth/focus/moy2008/index.html#mtw">Methods to Watch" for the past two years. But probe development has also overcome some big hurdles recently, from the bolus loading of small calcium dyes to the development of genetically-encoded calcium indicators capable of providing usable signals in living animals.

An editorial in the December issue discusses the advances taking place in optical probes for measuring neuronal function and calls for the use of more standardized procedures for evaluating new probes.

Nature Methods has been requiring a basic set of evaluation tests on new fluorescent proteins that we publish for a few years now and it is possible we could try and do something similar for genetically-encoded sensors but this would obviously be complicated by the greater complexity of sensors and the fact that they respond to different stimuli and have diverse applications.

We encourage the community to tell us what they think about the value and feasibility of standardized tests for new fluorescent probes and sensors.