Where are Thoughts?

The brain produces thoughts, but do thoughts themselves take up physical space - do they exist physically?  Currently, most if not all things which we are aware exist have some sort of physical manifestation, whether or not that manifestation is perceivable by our senses.  Apart from the obvious examples (rocks, air, water, etc.) even things like light are physically present.  While something may be in the same place as light, the light is still present and perceivable, whether by the unaided eye or by complex instruments.  Sound comes in waves, and we can measure gravity.  It is true that we can also measure brain activity, but that is simply measuring the amount of electrical impulses produced by the brain - we cannot see someone's thoughts this way.

It seems likely that thoughts are made up by combinations of electrical impulses in the brain, but it is difficult to understand exactly how a combination of electrical signals can produce an imaginary goat, or whatever other thought one may have.  Thoughts may be produced by the electrical impulses, but they are not the electrical impulses themselves.  Where, then, are they?  Or do they exist without being physically there?  Is that possible?

I am aware that this post asks a large number of questions and provides very few answers, but I don't know the answers, so I cannot present them here.  In fact, I don't even really have hypotheses on this matter - it merely seemed like it might be interesting to present these questions.  If anyone has any thoughts on the matter, I would appreciate hearing them!