I think you might have missed out on learning about the 2d Fourier transform and the meaning of "frequency domain". The standing wave patterns of the feedback l

I think you might have missed out on learning about the 2d Fourier transform and the meaning of "frequency domain". The standing wave patterns of the feedback loops are exactly the wave patterns you want to decompose the image data into. The waves have a characteristic frequency inversely proportional to the length of the loop. One can apply a decomposition into a wave basis just as easily on the space domain as one does on the time domain. The convolution in the original domain just becomes multiplication in the frequency domain. Sharpen and blur filters are literally just high pass and low pass filters applied to the 2d Fourier transform. I highly doubt there is one big pipeline to which the original sensory inputs go through some fixed filters and then return back to the main start point as feedback. It's not exactly like pointing your camera at the projector, or holding the microphone too close to the speaker. Rather, there's many possible paths for neural inputs to loop back, and none of these loops is the dominant "pipeline". It's more like a microphone is near a whole wall of speakers, each with its own characteristic delay and amplification factor. The repeating spatial patterns of whatever length directly translate to a standing wave in neural loops with the right amount of loop length. The transform to a convenient wave basis doesn't need to be implemented as a layer in a pipeline because the loops themselves are the transform. A transform into frequencies (in some weird basis) is almost an unavoidable consequence of connecting neurons at random. Just like any old metal sheet is a bell if you hit it with a hammer, any old clump of neurons is going to have standing waves of activations that resonate with some sensory input pattern. If you randomly poke at some neurons, possibly altering their delay time or adding/disabling connections, statistically the longer the loop the more likely it is to be affected. This view also nicely explains the other effects of LSD. Your sense of time is wrong for the exact same reason your perception is distorted: the timing of all the loops have been slightly detuned.