The Neuroscience of Christopher Nolan's Inception: Part 2

As a movie, I very much enjoyed Inception, and I'm currently prodding my family to see it again with me. But I'm not addressing the movie's merits as a movie.

Now that I've seen the thing and no longer have to rely on conjecture, I have a few more things to say on elements of the movie, mostly based off of areas that I misinterpreted given the limited information before the movie's release. Obviously, spoilers follow.

1) The difficulty of inception: I've already covered why planting an idea in someone's head really isn't all that hard. Interestingly enough, the movie's version of inception is more complex. It involves planting an idea and making sure that person believes the idea is his/her own. Cobb's argument for the difficult of inception is that people can always trace the source of their ideas if they were from another person. Which is, unfortunately, patently untrue. Tracing the source of an idea involves remembering where it came from. Neuroscience tells us that our memory is reconstructive. We don't remember events or facts in perfect detail--instead, the brain reconstructs events in a fashion that makes sense to it. This is why eyewitness reports, despite being prized by juries, are factually less reliable than other evidence. The ability of any individual to trace the exact genesis of an idea is pretty wishy-washy.

2) Knowing what you don't know you know: The concept of subconsciously knowing things that you're consciously unaware of is older than Freud, and actually has some truth to it. Certain kinds of learning do not require conscious knowledge of learning. Muscle memory is an excellent example of this, illustrated by the famous patient H.M., who had a disastrous surgery for epilepsy that left him unable to form new memories, and presumably an inability to learn new things. However, H.M. consistently improved at motor tasks like tennis, even though every time the researchers handed him a tennis racket, he claimed he had no idea how to play. Another good example of being consciously unaware of knowledge comes from split-brain patients, who have had the connection between the right and left hemispheres of the brain severed. The two halves of the brain then act almost independently, without sharing information with one another. From split-brain studies, it appears that for an individual to be consciously aware of a stimulus, the stimulus has to be processed somewhere down the line by the left side of the brain--the side responsible for language. It might be a stretch, but it seems like conscious knowledge of something depends on our ability to put it into words.

3) The nature of reality: The ending didn't really come as a surprise to me. It would be strange if a Christopher Nolan mind-screw of a movie gave us an unambiguous ending. However, the questions it raises are more complicated than the simplistic "are we brains in a vat" version. As I said in an earlier post, the difference between REM brain activity and awake brain activity comes down to the involvement of the prefrontal cortex, and the availability of sensory input. The way the dream machine worked in the movie seemed to preserve prefrontal cortex functioning for everyone in the dream: Cobb, his team, and Fisher. Otherwise, there is no way they would be able to plan, reason, and keep track of the elaborate heist.

Now, part of the reason why we can distinguish dreams from reality is their sheer weirdness. Without the prefrontal cortex to make sense of the activity of the sensory association areas of the brain, dreams flat out don't make much sense when we wake up. However, the dreams of Inception are fundamentally different from "normal" dreams. First of all, they are constructed by not the individual's sensory association cortices, but by an architect who pulls everyone into a shared dream. Secondly, the prefrontal cortex is active during Inception's dreaming. At this point, I'm venturing into the realm of conjecture, but it seems reasonable that a dream in which the prefrontal cortex is active and making sense of things would indeed be very difficult to distinguish from reality.

Overall, though, I did really like the film. And while a lot of Inception's claims either contradict or muddle what science has discovered about sleep and dreams, I have to give the movie props for constructing its own internal logic about dreams, and sticking to it. Hopefully, I'm off to see it again :)