The thalamus is a sorting center deep in the brain. It's the post office and it goes, oh, this came from the hand. I'm going to throw it off to a part of the cerebral cortex that deals with sensation that is mapped to my hand. And we've got a part of our somatosensory cortex, which is located in our prior to a lobe - basically has a whole body of sensation mapped to it. So it goes, something's happened to your hand. It's not a painful experience yet. It's simply sayingSomething's happened to the hand through a three neuron chain.