[Shish2k]

Actual noise with no coherent structure is enough for the brain to start imagining patterns - can confirm that having tried it myself, with white noise in my eyes and ears for half an hour, I ended up having dream-like hallucinations while awake:

https://en.wikipedia.org/wiki/Ganzfeld_effect

[pizza]

I want to say, pyramidal cell in visual cortex connectivity network decoherence - similar happens with mice after sleep deprivation, and is reminiscent of the phenomenon of HPPD, and with stochastic resonance.