[jjcm]

Here's the paper: http://neural.bme.ufl.edu/page13/assets/NeuroFlght2.pdf

It looks like they're using a combination of high and low frequency pulses as a reward/punishment mechanism, though I don't fully understand how that influences the decisions being made. Would love if someone could explain it in more detail.

[jostmey]

It is called Long Term Potentiation and is believed to be one of the ways information is stored in the brain.

http://en.wikipedia.org/wiki/Long-term_potentiation