In A Nutshell Stanford researchers traced a brain circuit loop, running from the spinal cord up through the brain and back ...

A series of recent studies in mice and rats has mapped specific brain circuits that appear to drive chronic pain, identifying ...

And here it is, modelled using LTSpice. It is the same circuit as the classic simple precision rectifier (set to pass the negative half-sine), but with the non-inverting input of the op-amp connected ...