came from neuroscience so the basic idea here this is a paper from 1999 that popularized predictive coding but the idea actually goes back about a decade earlier and the basic idea is this we start with an input we have a feed-forward signal we try and predict away the input and we subtract that off and we only send forward the differences now the original idea here was an efficient coding idea let's try and reduce the number of spikes we have to send because if we subtract away the things we already know then all we need to send forward is the