Though many times we’re given rhymes that are quite un-sing-able…
The limits of “Mind” vs. “Body”
I talk a lot about “mind” and “body” in this substack. For instance, I have claimed that anxiety disorders, and most other things labelled “mental illness,” are located “in the body” rather than “in the mind.”
One thing that always bothers me when I say this sort of thing is that there’s a very real sense in which it is false! Also, it sounds a little bit nuts … or at least like the sort of thing that only a certain kind of person would say or believe. You know the kind of person I’m talking about. Think crystals and long hair and tie-dye and veganism and all that. Now, there’s nothing wrong with these people! But what I’m saying is not supposed to be the sort of thing that only this kind of person can believe. If I’m right, then what I’m saying is empirically valid, scientifically testable, and rigorous — as well as hippie-dippie and free-range and tree-huggable.
This particular post is all about trying to make the distinction more rigorous and scientific.
“Body” aka “Limbic System”
When I say something is located “in the body,” that is intended to communicate what it feels like, from the inside. If you lie quietly and pay attention to your sensations, you will appear to experience them in your body. In other words, “in the body” is true from a “first-person” point of view.
But there’s also a third-person point of view. From this point of view, sensations take (at least in part) “in the brain.”
So let’s talk about the brain. In particular, let’s talk about the limbic system.
Here’s what the internet has to say about the limbic system:
The limbic system is a group of interconnected structures located deep within the brain. It’s the part of the brain that’s responsible for behavioral and emotional responses.
Scientists haven’t reached an agreement about the full list of structures that make up the limbic system, but the following structures are generally accepted as part of the group:
Hypothalamus. In addition to controlling emotional responses, the hypothalamus is also involved in sexual responses, hormone release, and regulating body temperature.
Hippocampus. The hippocampus helps preserve and retrieve memories. It also plays a role in how you understand the spatial dimensions of your environment.
Amygdala. The amygdala helps coordinate responses to things in your environment, especially those that trigger an emotional response. This structure plays an important role in fear and anger.
Limbic cortex. This part contains two structures, the cingulate gyrus and the parahippocampal gyrus. Together, they impact mood, motivation, and judgement.
For my purposes, there are a few important things about the structures comprising the limbic system.
First, the limbic system has a strong influence on our emotions and indeed on all of our sensations. Any time you feel an emotion or a sensation of any type (“in your body”), it’s probably being sent to you by the limbic system. Or, if you prefer a more brain-centric (or third-person) point of view, you can say that the sensation in your body is (in part) the working of the limbic system.
“Mind” aka “Frontal Lobe” (or, perhaps better, “Pre-Frontal Cortex”)
Second, the functioning of the limbic system is in sharp contrast to the frontal lobe, which is the location of thinking. Or, as this quick-n-dirty summary from Cleveland Clinic puts it:
What does the frontal lobe do?
Your frontal lobe handles many abilities, including:
Reasoning: This includes simple and complex processing of information. Logic, reasoning, judgment, decision-making and creativity all fall into this category.
Social understanding: Your frontal lobe controls your understanding of social norms and helps determine what you should and shouldn’t do or say.
Executive functions: Some examples of these include self-control and inhibitions, attention span and working memory.
Voluntary muscle movements: These are intentional movements, such as moving your hand to pick something up or moving your legs to stand up and walk around. Your frontal lobe also contains the brain area that controls the muscles you use for speaking.
Learning and recalling information: This is your brain’s ability to process and learn new information for later use. Your frontal lobe also helps retrieve information later.
In short, the frontal lobe is the location of the things that we call thinking.
Very often, in this substack, I write sentences like “experience X is happening in the body, not the mind.” If that language makes you feel like I’m being hopelessly unscientific and hippie-dippie, please translate it to “experience X is created by (or is part of the functioning of) the limbic system, not the frontal lobe.”
The most important part of the frontal lobe is the prefrontal cortex (sometimes abbreviated as PFC). The PFC appears to be where thinking really happens. It is located at the very front of the brain (hence the name) and is much larger and more complex in humans than in other animals. This appears to be why we are so much better at abstract thinking, reasoning, problem-solving, and planning than other animals — as well as language, culture, and social interaction.
Third, the structures comprising the limbic system are physically deeper within the brain than the frontal lobe and the PFC.
Notice in the picture that all of the elements of the limbic system (the bits in bright colors) are located toward the lower, central portion of the brain, near the spinal cord. The frontal lobe (including the PFC) is part of the cortex, which is the outer parts of the brain (the white bits).
The processing of emotions literally takes place deeper within the brain than thinking does.
Fourth, the limbic system is much older than the PFC.
In general, the brain evolved up and out. The lowest portions of the brain were also the first to evolve. As you scan your eyes downward and toward the center of the brain diagram above, you’re tracing the process of evolution in reverse, backward in time.
The brain stem, which is located at the base, below the limbic system, is the most primitive part of the brain, which means it’s shared with animals that branched off from us very far back in the process of evolution. The brain stem is also the part of the brain that’s most essential for life: it controls things like breathing, heart rate, temperature regulation, and bare consciousness (“conscious” as in awake versus asleep or anesthetized).
You can get by with most of your prefrontal cortex gone — you won’t know much about what’s going on, but you won’t die. You can live, to one extent or another, without a functional limbic system. (There was apparently a person who lost her amygdala and stopped being able to feel fear … interesting details at the link. Similarly there have been experiments in which the hippocampus is partially or entirely removed, and the person lived. ) But without a brain stem, you just die.
The limbic system is newer than the brain stem, but it’s older than the prefrontal cortex. In other words, the very earliest animals related to us could breathe and stay conscious and regulate their temperature and all the things controlled by the brain stem. Then along came later animals, which could do all these things but also have emotions of one complexity or another. And then, later, came the development of the frontal lobe and the prefrontal cortex, and with these structures came animals that can really think.
In short, feeling is older than thinking.
Human/animal
Fifth, the brain systems that create emotions in humans are basically the same systems that are present in much less intelligent animals.
Apparently all birds and mammals have limbic systems that are structurally similar to our own and that appear to work in a similar fashion, more or less. (Reptiles don’t, though, which is kind of cool. Some reptiles appear to have brain structures with some similarities to the limbic system, but the structures are different. Whatever emotions might be going on inside that turtle, lizard, or crocodile are hard for us to read … and that’s for a reason!)
Because the structure of the limbic system is so similar among mammals and birds, we should assume (until it’s proven otherwise) that the way the limbic system works is also similar across these species.
This idea also has both a first-person (subjective) and third-person (objective) component.
Subjectively. When you feel emotions, or any sensation, you’re probably having a very similar experience to emotions and sensations as they are experienced by other mammals and birds. Of course, there’s no way to prove this. But it seems to me that there is a very strong burden of proof on people who think that the way it feels to experience happiness, fear, sadness, or anger is substantially different in humans than in lions, mice, or ostriches.
Objectively. Because the limbic systems are so similar, we can gain real insight into human emotions by observing mammals and birds. Scientists who study anxiety in mice, for instance, are working with something that’s extremely similar to human anxiety. “Oh, it’s just mice, they’re not going to have our complex experiences, so anything you learn from them won’t apply to humans” —> No. Humans do have more complex PFC’s than mice, of course, and it would be stupid to try to model human thinking on mouse thinking. But our emotional systems are the same damn thing as what’s going on inside a mouse.
Here’s an example. Watch this cat.
Those of us who have experienced significant anxiety issues are naturally reminded of our own jumpiness in the face of certain stimuli. I believe this is 100% correct. This cat’s jumpiness is exactly the same sort of thing as our jumpiness. It’s being produced by the same systems, it has the same effects, the same symptoms. We know exactly what this cat is going through. (It sucks.)
I also think that, once we understand from the inside what causes anxiety in humans, we can design better treatments for anxiety in animals. As I wrote recently, my wife and I are working on this with our dog Cosmo. (I really want to write more about this. Soon, I hope.)
Sixth, the limbic system — not the frontal lobe! — is the primary place where memory happens.
Considered on a purely physical basis, then, our memories are more closely connected to our emotions than to our thoughts! Which makes sense, doesn’t it? In my experience, at least, I know that my strongest memories are those that evoke strong emotions — not those where I was thinking really well or had a really important insight.
Sometimes someone will say something to me and it will remind me of something. But the memory isn’t rational: it’s an emotion (often connected to a place, or a smell, or a song). It can take me a while to figure out why I was reminded at all — what the connection is. That the connection exists, and how the connection feels: I know that immediately, in my body (a.k.a. limbic system). The mental processing comes later and is slower.
The close relationship between emotions and memories is important for thinking about trauma. (How does trauma cause anxiety and PTSD in the first place? How do anxiety and PTSD remain in the body over time? How can we heal these problems and leave them in the past?)
Seventh, the PFC and the limbic system are physically separated from each other. They are connected via wires (neurons), but the connecting apparatus is fairly long and slow, compared to the connections within each part of the brain itself. The physical distance between them is important.
Here’s an edited version of what chatgpt has to say about the connections between the frontal lobe and the limbic system.
The limbic system and the frontal lobe are connected through a network of neural pathways that allow for communication and integration of information between these two regions of the brain. This is a bidirectional connection that allows for the integration of emotional, memory, and motivational information with higher-order cognitive functions.
Physically speaking, the primary connection uses a bundle of nerve fibers known as the fornix. The fornix carries information from the hippocampus [part of the limbic system], which is critical for forming and consolidating memories, to various regions of the frontal lobe, particularly the prefrontal cortex. Additionally, the prefrontal cortex has reciprocal connections with several limbic system areas including the amygdala and the hypothalamus. These connections enable the prefrontal cortex to regulate emotional responses and modulate behavior based on emotional and motivational input from the limbic system.
The distance between the systems is important. I’ll have more to say about this another time.
Eighth (and perhaps most important), the thinking and feeling parts of the human brain are very different things. The human PFC is larger and more advanced and more complex than any comparable system in any other animal on earth: it’s rational and sensible, or at least it can be. But the limbic system is very similar to other animals, it’s relatively simple, and very often there’s nothing rational about it.
The two brain systems work together — or so chatgpt would have us believe. But what happens when they fail to work together?
The insight that I have had recently — something that has become more and more clear to me — is that the PFC and the limbic system fundamentally do not understand each other. They’re not the same sort of thing and they don’t speak the same language. Think of all the problems a cat and a dog can have as they try to figure out each other’s body language. But this is much worse, because cats and dogs are much more similar to each other than the limbic system is to the PFC.
This leads to misunderstanding and confusion, even among people who think of themselves as emotionally healthy.
Here’s a tiny little example. A few days ago, I woke up and my back hurt. I was sure I knew why — I had just slept wrong, again. I have this feeling all the time! But then I thought … wait a minute. Yes, I used to have this pain regularly, but it’s been ages since I felt this way. Also, my bed is super comfortable, and I wasn’t asleep for that long. How could I possibly hurt this much? So I entertained a different hypothesis. Maybe, I thought, it’s an old emotional pain of some sort, an old trauma crying out to be processed and dealt with.
Why did my mind leap immediately to the physical explanation? Why do we normally assume that we can tell the difference between “pain that has an immediate physical cause” and “pain that is caused by long-forgotten trauma”? After all, they feel the same!
Most of the time we don’t (or won’t) recognize when our current physical pain is being caused by ancient emotional trauma. The mature adult mind rebels against the possibility that we could hurt this much, right now for purely psychological reasons … forgetting how much emotional pain we went through as children, and how little of that pain we ever processed.
Or maybe it’s not forgetting: maybe we want to deny that it’s even possible. “Wait, you’re telling me that I repressed emotional pain as a child, decades ago, and it’s been latent in me all this time, and it just happens to be returning today as a physical pain in my back and shoulder? How is that even possible? It doesn’t make sense. No, I probably just slept wrong.” But, please, think again. To whom does it not make sense? Which is the sense-making part of the brain? The PFC. The limbic system doesn’t play by the rules of the PFC.
The limbic system says “OUCH! I HURT! PLEASE LISTEN TO ME!” and the PFC says “meh, it’s just physical, nothing to do about it, let’s ignore it.” The limbic system says “there has been a specific sadness inside you for decades, and something just reminded you it’s in here, and it hurts, and you should deal with it, so here’s some big feelings.” The PFC says “I seem to be very sad for no reason. I look around and notice that nothing really sad is going on right now. Clearly something weird is going on and it makes no sense. The only rational response is to do the usual thing: push away the sadness, stay away from memories, and get back to work.”
In people suffering from serious anxiety or depressive disorders, things are much worse. The struggle between the rational beliefs of the PFC and the emotional charge of the limbic system can become a full-on war. Misunderstanding and confusion turn into mistrust, anger, and despair. Eventually, the disjunction between mind and body, PFC and limbic system, pushes us to have experiences that make no sense at all. That’s when we feel like we’re really losing our minds.
“The lunatic is in my head.” I lived in the reality of that sentiment for many months, maybe even a full year, during the depths of my anxiety disorder. I sometimes wasn’t even sure which part of me was the lunatic intruder! Sometimes it felt like I could be fine inside my rational mind, but my emotions kept bubling up and screaming at me for no reason. Sometimes I felt like I could be OK living with my emotional ups and downs if my mind would just shut up for one fucking second.
Wait, so you’re saying that unprocessed trauma can manifest as anything from an unexplained pain in the body that we dismiss and move on with our day … to a full-on psychotic break?
I think that’s correct, yes. I’m not saying it’s the only thing that can cause the most serious mental health problems — nor that this is the only possible reason that we can have unexplained physical pain! But I’ve experienced this phenomenon at different levels of intensity, and I’m convinced that they are, at base, the same type of experience.
The physical, brain-centric explanation, in both cases, is the mismatch between the PFC and the limbic system. We literally do not understand what’s going on inside our own brains. When we try to figure it out, we naturally draw on our rationality (a.k.a. pre-frontal cortex). But our most rational guesses are almost guaranteed to be incorrect.
I’m writing up an extended metaphor about all of this, which so far I’m very proud of. But (a) this is getting too long, and (b) I’m trying to write about brain science, not metaphors. So I’m going to end here. More soon.
Thanks for reading, as always.