I was just discussing the first bit last night with a friend. She told me that she has entire, back-and-forth conversations in her mind, pretty much constantly. Asking herself things, musing over answers, as if she was on both sides of a discussion over what to do and how to do it. Me? I have a crazy, trippy, disjointed monologue, jumping from topic to topic, as if my skull was occupied by Daffy Duck on speed. And generally there's a soundtrack, too, usually of whichever song I heard on the radio over the past 48 hours was the most annoying.
It's no wonder I have such difficulty focusing.
Some people are highly visual, and rather than words, they think in pictures. No internal chatter at all, which is hard for me to imagine. And I guess it's no surprise I don't think in images much, especially not images of people; being face-blind, I can't picture anyone's face, including my own. Nada. I know I have blond-ish hair and blue eyes and short facial hair and a big nose, but I can't put it all together into a composite image the way some people (apparently) do with ease.
Of course, in most ways I get by just fine. I was asked one time, "If you can't picture your own face at all, how do you know it's you when you look into the bathroom mirror in the morning?" I stared at the person for a moment, and said, "Because I know there's no one else in the bathroom but me."
I mean, I may be face-blind, but fer cryin' in the sink, I'm not stupid.
But I digress.
Anyway, there seems to be a huge variety of internal experience, which I suppose is what we should expect given the huge variety of outward expressions of that experience. But that brings us to the second question: what's happening inside our skulls that creates that internal experience in the first place?
Neuroscientists are just beginning to piece together an answer to that question. We have a pretty good idea of where in the brain certain activity occurs; higher-order processing in the prefrontal cortex, motor coordination in the motor cortex and cerebellum, spatial navigation in the hippocampus, speech production in the Wernicke's and Broca's areas of the cerebrum, and so on. Even my own particular difficulty, which goes by the medical name prosopagnosia, has been localized to a place called the fusiform gyrus, which in the face-blind simply doesn't respond when confronted with an image of a face. So we can see it just fine, but we don't recognize who it is. (It manifests in me as everyone looking vaguely familiar -- so when someone starts talking to me, I can usually slip right into acting like I know who I'm talking to, when in fact I very rarely do until I recognize the voice or pick up context clues. But I'm good at faking recognition, at least until I get fed up fishing around and say, "I'm sorry, but I have no idea who you are.")
But other than the general locations in the brain where certain functions occur, we're still largely in the dark. Think about something really simple that isn't in your mind before the question was asked -- for example, what did you have for dinner last night?
Now, where was that information before I asked the question? How was it encoded? How did you retrieve it? Even weirder are those moments when you know you know a piece of information, and it's in there, but you can't get at it -- the "tip of the tongue" phenomenon. And why, when you stop worrying at it and start thinking about other things, does the answer spontaneously pop out? (In the days before Google, when finding out factual information usually required a trip to the library, I was driving myself nuts trying to remember the names of the Three Musketeers. Athos, Porthos, and...? It was a full two days later, while I was out for a run and completely thinking about other things, that suddenly my brain went "... Aramis!")
What about when we're trying to make a decision between two alternatives? For me, I'll bat back and forth between them, then -- quite suddenly -- I settle down into one or the other. And just last month a paper in Cell has suggested that what's going on in the brain might be exactly what it feels like, only much, much faster.
In "Constant Sub-second Cycling between Representations of Possible Futures in the Hippocampus," a team led by neuroscientist Kenneth Kay of Columbia University found that rats confronted with a choice in maze-running shuttle back and forth quickly (about eight times per second) between patterns of neural firing representing the two choices -- as if they were thinking, "Let's see, I wonder what's down the right-hand path? Hmm, how about the left-hand path?"
The authors write:
Cognitive faculties such as imagination, planning, and decision-making entail the ability to represent hypothetical experience. Crucially, animal behavior in natural settings implies that the brain can represent hypothetical future experience not only quickly but also constantly over time, as external events continually unfold. To determine how this is possible, we recorded neural activity in the hippocampus of rats navigating a maze with multiple spatial paths. We found neural activity encoding two possible future scenarios (two upcoming maze paths) in constant alternation at 8 Hz: one scenario per ∼125-ms cycle... Notably, cycling occurred across moving behaviors, including during running. These findings identify a general dynamic process capable of quickly and continually representing hypothetical experience, including that of multiple possible futures.There are a couple of interesting things about this. First, there's the role of the hippocampus; higher-order decision-making is traditionally thought to be the provenance of the prefrontal cortex, although the fact that this decision has to do with spatial navigation is probably why it occurs where it does. Second, why is the cycling so fast -- each flip lasting, on average, an eighth of a second -- when it feels very much like we're considering each possibility slowly and deliberately? (Of course, that's assuming that our neurology and experience are both comparable to what's happening in rats, which may be a poor assumption.)
I also wonder what's happening with the consideration of imaginary scenarios. Being a fiction author, I do that a lot, and I know I spend a great deal of time testing out various ideas and plot twists before settling on the one that I want. It's quite remarkable when you think about it; we're capable of dreaming up highly detailed and completely counterfactual scenes, and interact with them as if they were real -- deciding which path to take, which of the two magical doors to open.
As author and journalist Kathryn Schulz put it, in her phenomenal TED talk "On Being Wrong," "The most wonderful thing about the human mind is not that we can see the world as it is, but that we can see the world as it isn't."
But this is just the first step of solving that most fundamental of questions in neuroscience, which is how we emulate our experience in our brains. This is one small piece of the puzzle of human consciousness, the origins of creativity, imagination, and memory, the last-mentioned of which hopefully will solve how I can set a tool down and literally thirty seconds later can't remember where I put it.
One of my favorite people is the indefatigable British science historian James Burke. First gaining fame from his immensely entertaining book and television series Connections, in which he showed the links between various historical events that (seen as a whole) play out like a centuries-long game of telephone, he went on to wow his fans with The Day the Universe Changed and a terrifyingly prescient analysis of where global climate change was headed, filmed in 1989, called After the Warming.
One of my favorites of his is the brilliant book The Pinball Effect. It's dedicated to the role of chaos in scientific discovery, and shows the interconnections between twenty different threads of inquiry. He's posted page-number links at various points in his book that you can jump to, where the different threads cross -- so if you like, you can read this as a scientific Choose Your Own Adventure, leaping from one point in the web to another, in the process truly gaining a sense of how interconnected and complex the history of science has been.
However you choose to approach it -- in a straight line, or following a pinball course through the book -- it's a fantastic read. So pick up a copy of this week's Skeptophilia book of the week. You won't be able to put it down.
[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]