The notion of a distinction between a more constant "detection threshhold" and a more variable "tolerance threshhold" is, I think, a useful one. I'm less sure that that exactly parallels "acute" and "chronic pain" or that the notion of interneurons influencing the transmission of pain signals can account quite so straightforwardly for the detection/tolerance difference, to say nothing of additional phenomena like phantom limb pain. If nociceiptive signals were being inhibited by interneurons, wouldn't that affect both detection and tolerance? And how does one account for pain in cases where there are no nociceptors? Maybe there is something more going on both in at least some cases of chronic pain as well as in reducing pain with training?