What It’s Like to Be a Fish

Have you ever wondered what it’s like to be a fish? Not a person in a fish body – I mean, have you ever wondered what it would be like to have a fish brain – a fish mind?

A disoriented goldfish.

Here’s another question: do you have a self in your connectome that tends to…well, to whine a lot? Maybe it doesn’t always whine in words – a lot of the time it’s in emotions – but when it’s an inner voice, it says things like, “Let’s just stay here – it’s safer here,” or, “Sure that’s great to think about, but actually doing it would be too hard.”

Now, let me ask you: do you think fish have an inner critic like that? What about reptiles?

I want to talk about where that inner voice comes from. I want to talk about taming it. Eventually, I want to help you learn to reprogram it.

But it’s going to take a couple of posts. To really understand what’s going on, we have to go back to fish.

A delicious-looking fish brain.

See, fish seem to have been the first animals to develop a cerebrum – what we think of when we think “brain.” But the cerebrum is just one part of fish brains…

– the brainstem (myelencephalon) regulates muscle reflexes, respiration, and other dull-but-crucial survival tasks

– the hindbrain (metencephalon) is mostly composed of the cerebellum, which deals with balance; it sits just on top of the brainstem

– the midbrain (mesencephalon) is mostly made up of the optic lobe; it first appeared in primitive fish, to deal with processing complex visual data

– the cerebrum is composed of two main parts:

1) the interbrain (diencephalon) which monitors and relays incoming information from sensory and muscle neurons, as well as those throughout the brain

2) the forebrain (telencephalon) was at first mainly used for smelling things; it’s made up of the pallium – a distant ancestor of the cerebral cortex – and in some fish, a smaller subdivision known as the olfactory lobe (subpallium)

Like I mentioned, fish used their pallium – known as an archipallium – mostly for processing smells. But the cerebrums of a few fishes and amphibians evolved more ambitiously. Their interbrains began to specialize into structures like the thalamus, which regulates sleep rhythms, and plays a major role in coordinating motor function. On the whole, the thalamus seems to receive incoming signals from neurons, and route them – selectively – to other brain areas through a set of structures called the basal nuclei.

Here’s where we get into the most mysterious role of the thalamus – its interplay with the cerebrum. The basal nuclei allow the thalamus to receive signals, not from outside sensory input, but from another area of the brain, then respond by routing signals to yet another area – enabling a brain to be aware of (and respond to) its own states. This may not be consciousness, exactly – but it represents the leap from just having the feeling of anger, to being aware that you are feeling anger. That’s about as far as most reptiles got.

Meanwhile, the basal nuclei were developing into functional clusters called the basal ganglia. In mammals, these are a component of the thalamo-cortico-thalamic circuits which may be responsible for producing the feedback loops associated with subjective consciousness. As mammals got smarter, the cerebral cortex got larger, and eventually developed the lobes that allow us to speak, memorize lines, and perform the other sorts of tasks usually associated with sentience.

So, what does all this have to do with the inner critic?

Well, there’s a pattern that starts to become clear throughout all this analysis of the brain’s history: it’s a lot easier for evolution to co-opt an existing structure for a new purpose than to develop an entirely new one. Some theories, like the Triune Brain hypothesis, actually group the brain’s structures into semi-separate “systems” or “layers” of consciousness. At any rate, it’s clear that in mammalian brains, a wide variety of instincts, emotions, and thoughts are constantly competing for the spotlight.

Now, in the forebrain there’s an area called the cingulate cortex that probably plays a major part in this ongoing brain-chatter. The cingulate cortex is folded on top of and around the interbrain, and seems to help us reconsider our instinctual desires, especially in social situations. (If you’re into the Triune Brain hypothesis, the cingulate cortex is considered a major part of the limbic system.) It’s not particularly associated with rationality – instead, it seems to help some emotional reactions “debate” with other ones before the body takes action.

The anterior cingulate cortex helps modulate the brain’s responses to stress, including social pressures. A deficiency or suppression of the synaptic protein neurabin in the anterior cingulate cortex has been implicated in anxiety disorders and paranoid schizophrenia, where patients often feel that “inner voices” are constantly judging and mocking them.


Which is pretty interesting, because the posterior cingulate cortex may be helping to dream up some of those voices. The area has been linked with the brain’s ability to model the behavior of others – to imagine what they probably believe, and how they’ll probably act. An overactive posterior cingulate cortex, combined with an anterior cingulate cortex that’s not modulating those signals effectively, might contribute to a feeling that one is under constant “inner criticism.”

Some patients say drugs that suppress signals coming from the posterior cingulate cortex (dissociatives, for example) help silence their inner critic, allowing them to just live “in the moment” without worrying about what others think. This is an easy slope to slide down, though: people who abuse dissociative drugs may find that they lose the capacity to self-regulate, or even to assemble a coherent sense of self.

In short, a connectome has to maintain a delicate balance between gratification and regulation – between acting heedlessly on instinct and self-analyzing to the point of paralysis.

Luckily for fish and amphibians, their brains don’t seem to have the neural hardware to support this sort of an inner critic. Now, I do want to point out that some neuroscientists, such as Oxford’s Gero Miesenböck, have identified simple “critic” neurons that modify fruit fly behavior, and even used those neurons to remotely control these animals. But even if these neurons have some functionality in common with the human cingulate cortex, they operate at a much more instinctive level of direct feedback – they’re much too simple to create an actual internal dialogue or debate. For that, we need at least some measure of what we might call self-consciousness.

In this same vein, mice can definitely get paranoid about pain, but they don’t seem to worry about much beyond their basic physical comfort. In other words, anxiety about abstract ideas – or about one’s own characteristics – seems to be the price our mind pays for modeling a “self,” and analyzing complex social environments.

Of course, it would be overly simplistic to say that the inner critic is the voice of a cingulate cortex gone haywire. Science doesn’t seem to support the idea that such a “voice” really originates, or is localized, in any one area of the brain. But here’s a thought that I think is worth considering: maybe these “selves” we keep hearing about are actually the desires and intentions of various communication systems in the brain.

Here’s what I mean: evolution hasn’t changed the essential structure of the brain since the days of fish – it’s just woven in layer after layer of more complex structures. What if most of those relay systems generate selves of their own? What if, as the brain evolved, none of those selves was ever silenced, even as new ones were added on? Maybe they constantly interrupt each other. Maybe they disagree with one another, and send out signals that they’re upset. Maybe a bunch of them are constantly scrambling for a spot in the consciousness seat – for a moment of control.

I mean, just give the idea some thought.

You might also try a bit of an experiment: the next time you’re gearing up for a new and potentially scary experience, and a little voice in the back of your mind pipes up and says, “I’m scared,” ask it (nicely), “Who are you?” You may be surprised at the response.

In the next post, I’m going to get into some more practical stuff: we’ll talk about the human connectome’s feedback systems, and how consciousness uses speech to self-modify.

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