We normally think that our consciousness is unified. We think that our beliefs, desires, and perceptions all have the same subject. For example, it seems like my perception of a computer and my belief that coffee tastes good have the same subject, not multiple disconnected subjects.
However, it turns out that recent neuroscience has a bearing on this belief about consciousness.
From Philosophy of Mind: A Contemporary Introduction by John Heil (p. 85):
Another worry that I have left untouched concerns the unity of experience. On the one hand, the brain is a complex system encompassing endless subsystems. On the other hand, our mental lives are apparently unified. Although we all possess various distinguishable mental faculties, at any given time each of us confronts the universe as a single ego with a single point of view or perspective. (This is so, I suspect, even for persons said to possess multiple personalities.) How is this unity of experience to be reconciled with the widely dispersed and fragmented character of neurological processing?
In recent years, hopes for finding a neurological ‘central processing unit,’ a neurological analogue of a computing machine’s CPU, have receded.
There is no central location in the brain where everything comes together, and that has implications for how we think about the unity of consciousness. One way of interpreting this finding is to conclude that the unity of consciousness is an illusion, which is the interpretation taken by Daniel Dennett. Another way of interpreting this is to conclude that consciousness is unified and therefore distinct from the brain, which is consistent with the dualism of Jonathan Lowe.
This underlines how important it is for philosophers of mind to pay attention to neuroscience in formulating their theories.