Optical Topography is a new way to study the activity of the brain. It monitors the concentraion of haemoglobin and deoxy-haemoglobin by shining infrared lasers of 695nm and 830nm into the brain. The 695nm laser detects deoxy-haemoglobin and the 830nm laser detects the haemoglobin, just like in those spectrophotometers that you use to do assays in a biochemistry lab.
They use a grid system of lasers and detectors on the head to detect the reflected infrared light.
Really neat, I wonder how well it works. It would work well with a traditional EEG, I think.
I also learned about Magnetoencephalography in this article, I'll have to check it out.
