I'm spending this particularly sunny Saturday in Manhattan doing some literature reviews near an open window overlooking people eating at an outdoor cafe`on 3rd avenue. Unbeknownst to them, I've been watching and wondering about the connection between the food they're eating, their bellies, and their brains. I know I shouldn't get derailed from finishing my work, but I couldn't resist writing this post.
I just came across a review paper called "Gut feelings: the emerging biology of gut-brain communication." Cool stuff. Apparently, there has been talk since about 1850 of a nervous system I've never heard of before: the enteric nervous system (ENS). Technically, it is considered the 3rd branch of the autonomic nervous system, which I'm certainly familiar with, but still! The ENS seems a bit too important for me to have been enveloped in the field seven years before learning about it. It could just be me... but I'm guessing the folks in psychology are not all that knowledgeable of the ENS.
That being said: the ENS, - or the interaction system between the brain and the gut - is referred to as the 'second brain' because it is similar in complexity to the one we have in our heads. It turns out that the second brain may have a pretty big impact on emotions, motivation, and [get this] intuitive decision making. In other words, the gut is quite literally involved in making gut decisions.
Who would've thought? Actually, the guy who coined the phrase "gut feeling" may have.
Consider the fun little notion that maybe we have been able to identify that intuitive decision making comes from the gut all along, without ever having scientific evidence. I love the idea that purely being mindful of your own physiological sensations can be an accurate source of information. How incredible.
Another interesting piece of knowledge this article has to offer is this: disruption of the ENS is associated with inflammatory gastrointestinal disorders, obesity, and eating disorders. To me, this certainly makes a lot of sense!
Specifically relating to over-eating, the paper proposes that the underlying biological mechanism is the mismatch between the big expected reward from eating food, and the relatively small actual reward experienced. The idea is basically that people keep thinking they are going to really enjoy food, are left unsatisfied, and keep coming back for more. While this may certainly be a big part of the picture, I have some other ideas about this... Something to think about for later.
Mayer, E. (2011). Gut feelings: the emerging biology of gut-brain communication. Nature Reviews, 12, 453-466.