You are walking down a long tunnel. The tunnel is lit but only dimly. You grab your flashlight. The light reveals rows of pipes lining the walls. Where do these pipes come from? Where do they end? You continue to explore. You learn lots more details about the tunnel. Will this help answer your questions? Perhaps. But perhaps not. Maybe it is only when you step outside and examine the surrounding environment that the purpose of the tunnel becomes clear.
With an important caveat, I think something similar is true when it comes to investigating the brain. For while the brain is obviously not a tunnel, examining the brain, like wandering through the tunnel, can only tell us so much. For some questions, we are simply going to need to step outside people’s heads.
What is the mind? Imagine lying on a sandy beach, warming yourself in the morning sun. Where is your imagined thought? Is it located inside your head? If I were to (somehow) open you head and probe your brain, would I find it?
The question itself is confused. Imagining, like thinking, is a capacity, something we are able to do. And while it obviously occurs somewhere, such a capacity does not (nor could it) occur inside your brain. Instead, you realise your capacity to imagine when, for example, you describe to me your imagined thought (you are on a beach in Greece, you have just swam, the sand feels itchy etc).
Importantly, this acknowledges the crucial role of the brain. A functioning brain is quite clearly a necessary component for imagining or thinking. Further, depending on the questions that interest you, examining the brain may give you the answers you seek (tunnel specialists are always needed).
Still, for other questions, we will need to do something very different, namely take seriously the reminder that it is what we say and do that reveals our mental lives. The advantage of doing so however is that it clarifies that we examine the brain, not in order to settle thorny questions about what the mind is, but rather because the brain is part of those material underpinnings that make our imagining or thinking possible. And investigating those underpinnings can tell us new and surprising things.