A mind that has never been stimulated has no basis by which it could learn. My theory is that all thought, knowledge, and imagination, and even the qualia of conscious existence must call upon declarative memory to exist, and that memory must in turn call upon perceptual stimuli.
Imagine for a second a simple problem, say "1+1=2", but try to do it without any tactic that could only be informed by perception. The moment any shape or spatial memory is noticed, quell that thought and try again. You might then resort to audible memory, or using 1 or 2 distinct feelings, but once again, if those types of thoughts arise, stop and try again.
Next, try to recall what a "refrigerator" might be, but as before, stop immediately if the imagining of any physical shapes, sounds, feelings (like coldness), smells or tastes (like foods) occur.
Can you do it? I can't.
The next one is a bit more ambiguous but interesting. Find a quiet, dark room and lie down, close your eyes, and try hard to focus on nothingness. Ignore the feeling of fabric against the skin, the sounds of friction, the feeling of breath against your nasal passages, the feeling behind your eyelids or the weight of the brain in your head, the feeling of dryness in your mouth, or food (or lack of) in your stomach... Try as well not to imagine any senses, or recall any visual or audible memory, or smell or taste or touch or emotion. If it is even possible to get this down perfectly, it should simulate what lack of perception feels like (oxymoron maybe?). My guess is it would also simulate what unconsciousness feels like.