Overlaid on the micrograph of the fish is a slice of its brain measured with a laser scanning microscope, in which single neurons are visible.{credit}(courtesy of Ahrens et al.){/credit}

Sometimes an experiment will just reach off the page and slap you in the face, demanding attention. This happens to me every so often and I must admit, our latest paper from the lab of Florien Engert induced such an experience. There have been several cool, technical tours-de-force (is that proper grammar??) over the last few years involving different creatures navigating in a virtual environment while neuronal activity was monitored. These include a mouse running on a spherical treadmill, as well as a fly marching along a similar treadmill-style ball. But in these examples, having the subject head-fixed (for the stability of recordings in the brain, either with electrodes or through imaging) was moderately non-intrusive since walking motions were independent of the head. The same can’t be said for the subject in this latest example of a virtual reality navigator: a wriggling, swimming fish. Therefore, a more creative solution had to be sought and in a paper published online yesterday, Ahrens, Engert and colleagues decided that paralysis was the way to go in order to follow the neural activity of this navigating fish. Continue reading →