When a sense is lost, associated parts of the brain are often repurposed and take over other functions. For example, the visual cortex in blind people often begins to hear or read braille.
However, if there are no signals coming in through the optic nerve, then you’d expect that there wouldn’t be any signals coming in through the thalamus and into L4 of the cortex.
In this case, what’s driving activity in these cortical regions? Is there some other pathway that allows signals to make their way to the visual thalamus? Is there an alternate pathway that signals take through the cortical column? Is there just a ton of random connections everywhere like how voting works in HTM theory?