Our brains are amazing! We often take for granted the sensations and perceptions and phenomenological experience different clusters of neurons give us. We become acutely aware of what these neurons do when we induce fatigue in them. Here are a few examples:
1) Wernicke's area is involved in language comprehension. It is the area of the brain that allows us recognize the meaning of words. To fatigue this area, say the same word over and over and over again until the word doesn't even seem like a word anymore. There is this weird disconnect, it is like a flip has been switched and the word is now meaningless.
2) Our brains treat faces differently than other visual objects. Face recognition generally activates a different area of the brain -the right middle fusiform gyrus - than non-face object recognition. There have been some remarkable studies with split-brain patients that have shown if you present paintings of faces created out of inanimate objects such as vegetables to the part of the brain responsible for face recognition, the patient will say they saw a face, but if you present the same painting to the hemisphere that does not have the face recognition area, the patient will report that they only saw vegetables.
Anyway, if you want to fatigue the face recognition area of the brain, stare at a picture of a face for a long time, until you lose the sensation that you are looking at a face.
3) There are many more examples, but I want to skip to the cool stuff. Some people report that through meditation they can reach a state in which they can see their hand, but it no longer seems to be a part of them. It is like the hand is just as separate from them as the desk in front of them. There is a part of the brain responsible for making us feel like our body parts are part of us (very useful from an evolutionary stand point). Apparently, some drugs can produce that same sensation achieved through meditation.
4) The sense of self, which comes from an area of the brain behind the left ocular cavity, has been reportedly lost temporary during episodes of meditation.
There are other odd sensations, or rather loss of normal phenomenological sensations, that can be achieved through meditation or drug use. I think what meditation and drugs are doing is causing below normal activity in the parts of the brain responsible for those normal experiences.
Many people want to attribute something mystical or supernatural to these odd sensations. But, I believe they are produced by hypoactivity in specific parts of the brain responsible for things like making a word "feel" like a word, a face recognizable as a face, a hand being perceived as belonging to us, or for producing our sense of self.
We are amazing creatures, and I am facsinated by the inner world produced by a collection of neurons. No spirit seems to compensate for the abilities lost due to neural damage. The ability is just gone.