I’m sure you’ve all heard of the so called dream recorder and I’m sorry if this has been brought up before…
Now I don’t claim to be an expert in neurology… but my understanding is that the images received are from neurons fired in the visual cortex, after receiving the images on the retina, and this was how the above picture was obtained…
But when REM sleep is activated, the primary visual cortex is not activated, only the secondary cortexes (cortices? 
) and so the dream recorder would not actually be recording the genuine dream, but rather mixed images from the secondary cortex areas.
I’m sure that as science and technology progresses, we’ll be more able to map the neurons from these cortexes… but for now… i don’t believe we are in a position to record our dreams just yet.
Correct me if I’m wrong though 