Large-scale, high-density (up to 512 channels) recording of local circuits in behaving animals.

J Neurophysiol. 2014 Mar;111(5):1132-49. doi: 10.1152/jn.00785.2013. Epub 2013 Dec 18. Berényi A, Somogyvári Z, Nagy AJ, Roux L, Long JD, Fujisawa S, Stark E, Leonardo A, Harris TD, Buzsáki G. In this paper, they did something pretty mazing. They engineered an implantable device, which was made of 5 small electrode arrays, each with 32 recording probes. This, and its assorted electronic accoutrements, fit on a mouse's head (although it looked somewhat comically large). Looks aside, they were able to record field potentials on 256 channels from within the mouse's brain. They talk about how they had to do a lot of software multiplexing, so the recordings are not exactly simultaneous, but they switch recording channels once every 1.5 microseconds, which lets them sample every channel in sequence in less than 50 microseconds, still giving them an overall sample rate of 20KHz. If that's not cool enough, they were able to double the hardware on rat brains and record from 512 cortical sites. Coolness factor aside, this is awesome because they were able to reconstruct microcircuitry within the brain and see which cells had monosynaptic inputs on which other cells. That's not easy to do, but when you have 512 probes going at once, I guess that makes some things easier than ever. -DH