The Meaning of Life and Other Vegetables

Hello everyone.

The more scientific papers I read about Dopamine, reward, how addiction starts and perpetuates, and so on, the more confused and uncertain I seem to get. Normally, I’d have resorted to looking for a good popular-science book about the topic, and would have read it. But I’m afraid that when it comes to Dopamine and how it works, and maybe when it comes to human neurobiology in general, that avenue doesn’t currently exist. Not that there are no books available; it’s more a question of their worth, and if I want to be fair with the authors, a question of whether that research field is mature enough for moving on to the popular-science phase. My own answer is a capital No. From the papers I read, my impression is that there is a lot of uncertainty (even confusion) amongst current, active researchers; that ideas and theories are changing every year, sometimes supported by new research evidence; and that more than a few concepts considered “quite about right” as little as 5 years ago or so are in the “well, actually that’s not how it works” department today.

Typical scenario: I pick up a peer-reviewed paper from am esteemed scientific / medical journal, published in, say, the last 3 years, and I start reading. Quickly I come across some references. Best case: the reference is from the 2020s. The worst? They go back as much as you can imagine, well into the 20th century. “What’s wrong with that?” you might ask, “Science is science”. I agree, but when you’re reading about cutting-edge research, and the front line backing reference for an observation / insight on something currently considered “highly complex and not yet fully understood” is from 30-something years ago, it’s a little disturbing, or at least disappointing. But that’s not all. If I keep digging through the references – even when the first stop is in the 2020s – I arrive, after 1-3 additional steps (references in the referenced papers), at a 20th century published paper (it can even be the 1950s!…), more often than not citing some rudimentary study of rats… Yes, I do have some basic understanding of how science works, and how research is built up in layers over decades. But I feel that that’s not the case here. It’s not that each reference step is mentioning prior work and then adding something new; it feels more like simple repetition of older notions, many times without adding anything derived from fresh lab (or other) work. Don’t get me wrong, I’m not saying that all those papers didn’t add any new insight. All I’m saying is that the insight most of them add is not about precise neurobiology mechanisms and how they manifest in macro human behaviour.

I have a (maybe bold) intention to try to sort out what a fairly-intelligent lay person can currently gather about those topics. It is quite a formidable task, no doubt. Even highly qualified and experienced researchers currently working at the cutting edge in this field state clearly that the concerted workings of the various neurotransmitters, affecting multiple, highly varied, systems and physiological processes, are highly complex and highly nuanced. My advantage, in that respect, is that I am not bound by scientific precision (meaning, I can stay high-level, even a little vague), and I’m also free to go wild in my speculations (though I’d like to think of them as reasoned / rational), without being immediately ridiculed… Wait, I think that some of those esteemed researchers have been acting that way already… Haha. Never mind.

My starting point today will be the physical sensation of pleasure, which I already briefly related to. I’m not convinced that the pleasure physiology in humans is fully understood and mapped, scientifically (and to be fair, I haven’t read too much about that specific aspect of research); but I feel that it’s nevertheless a solid starting point. The reason is that it’s something almost all of us are familiar with, first hand; it’s something that seems to be hard-wired, to a degree, from the moment of birth; and it’s something that in the absence of pathology seems to manifest quite unambiguously. In short, it’s a clear signpost: We feel pleasure and then we seek to have more of it (simplistic, on-average; but quite representative).

I’m going to take a little detour here, though, if you’ll excuse me. I know, it’s annoying. Well, I never promised that this was going to be a pleasurable ride (pun intended)!… I wouldn’t say I’m trying to chart an uncharted territory, but It’s like I’m wandering around the perimeter and trying to fine a gateway, so please bear with me. I might take additional detours down the track, and I apologise upfront.

The point I want to make now is that pleasure is a flexible, “free will” driver. But why do we even need a driver?… I speculate that it’s suitable for “Beneficial, but…” situations (where that “but” can be all sorts of relevant, external or internal, circumstances). Where the reward is such that calls for discretion in its pursuit. For critical-to-life functions no such discretion is needed or allowed. For example, our body doesn’t need to be motivated (or driven) to pump blood. Hence, we don’t feel pleasure simply on account of our heart beating. Blood circulation is so essential, that evolution made sure that action to fulfil that need is hard-wired.

Actually, it seems that there is an additional tier in between hard-wired life-preserving circuitry and discretionary pleasure. Hunger and thirst can be very strong drivers without entirely relying on the promise of pleasure when finally addressed. When hunger or thirst become significant enough, they might take charge over our actions, but not in a heart-beating fashion – it still involves awareness, and choice, though the latter might seem to diminish as time passes on and the need intensifies. Then, if we don’t act effectively, they will eventually trigger pain. Pain is an interesting chap. Pain is like pleasure’s big (ugly?) brother. They both provide a powerful beacon that guides action, but that action is not automatic. When to act, and what to do, is up to us (at least to a degree – when physical pain is too intense the reaction might arguably be automatic). Perhaps it’s a useful metaphor to think of pain and pleasure as “bad cop / good cop”.

Why did I even bring it up? To say that there is something not quite satisfying in talking about “compulsion” in the context of the pleasure-driven action-inducing circuitry. If there was an unwavering need to ensure something necessary was going to happen, it would’ve been hard-coded by evolution; refer heart beating. If it was something a little less urgent (but still potentially life-threatening), it could (would?) have been coded as a drive like hunger or thirst (or physical pain). Pleasure seems to code for the lowest-urgency rewards. Maybe we are looking at a mechanism of “acquired hunger sensation”…? Not the obvious (potentially brutal), hard-wired hunger sensation, but a sort of hunger that can be learned. A sort of adaptability that gave an advantage at some point in our evolution.

Back to pre-detour…

Consider a baby just born. A standard recommendation (and maybe a motherly instinct?) is to offer the newborn to breastfeed. So, in many cases this is one of the baby’s first experiences in the new world. It’s not uncommon that the baby responds to the triggers, and tries to attach and suckle. I have no reason to think that it happens because of some pre-conceived knowledge of the potential reward, or an expectation of pleasure (for example, from the taste of milk or the feeling of a full stomach). Much more likely (to me) it’s a genetically hard-wired instinct. Why? Because it’s quite critical to a newborn to start feeding (and also receive many other benefits maternal colostrum can provide) fairly soon after birth, as soon as the opportunity is presented. In the wild, when apes evolved, a newborn that didn’t start feeding soon after birth wouldn’t have survived, and their particular DNA (one that didn’t code for prompt instinctive feeding) wouldn’t have kept going in the DNA pool. So what we see now is DNA that indeed promoted it. That’s what’s left around.

Now, I’m going to assume the baby feels pleasure when suckling. In other words, the baby’s Hedonic Hot Spot is stimulated and eventually it lights up. How do I know? I don’t, but it doesn’t matter right now. I’m trying to speculate a plausible chain of events, starting from a clean slate (sort of), that will allow discussing how drives get established based on feeling pleasure.

For the pleasure to start driving a specific behaviour from this point on, where no hard-wiring exists, and also no pre-conceived notions, a certain memory-coding mechanism would be needed. If we use computer technology as an illustration, the preceding choices & actions would need to sit in a “rolling buffer” – a short-term memory where the contents “await” a verdict regarding their pleasure-triggering worth, which is constantly being overwritten with newer content. If no pleasure arrives fairly soon, it means the last-stored choices & actions must be worthless in that sense, and can be discarded (simply by new ones coming in and written over the same buffer space). However, if a burst of pleasure is experienced, some sort of cascade would “commit them to memory”, with some sort of tagging that would say “This bunch here has potential to generate pleasure”. The implied meaning is that those choices & actions promote sustaining the DNA in the pool. Perhaps there is also a potence indication attached, in line with the intensity of pleasure felt (implied: and the relative DNA-sustaining potential). Every time pleasure is felt for that particular set of choices & actions, “pleasure worth” would be added to that memory; so both more intense pleasure sensations and recurrence of pleasure-triggering by that specific set will make that specific memory more potent.

The last element that would be required for that “pleasure library” to be an effective driver of behaviour is a retrieval mechanism that would push specific action sets into the “execution queue”. If a memory just sits in storage without an actioning mechanism, that’s all it is – a memory, regardless of any potential reward it codes for. I can think of two basic ways in which such retrieval would work. The first is a “similarity scanner”. The contents of the pleasure library would be constantly scanned (or be available concurrently, just beneath consciousness threshold), until a “Hey, this looks like what’s happening right now” moment occurs. The mind would become aware that the real-world prevailing conditions are close enough, and that making the certain choice or taking the certain action is likely to lead to pleasure. Time to go to town! Memory retrieved, action instruction pushed into execution queue, action taken, pleasure triggered. Done!

This first path is quite straightforward. In simple words: We remember what caused us pleasures, and when the conditions are similar – we do it again. The other pathway I speculate is more subtle, though (and perhaps more relevant to addiction). In that pathway, the pleasure memories take on a life of their own. They don’t “wait for a chance”; rather, they keep nagging regardless (with intensity proportionate with their pleasure potential), asking us to generate the conditions that will allow them to materialize and trigger pleasure. Needless to say, in such a mechanism it would not matter how wide the gap is between what’s currently and realistically available around us, and what the memorized pleasure-generating conditions are. Most of us would know – sometimes we go to great extents to move from “what is” to the conditions required for being in a position to take the final pleasure-inducing step, and get that hit.

So, “opportunistic” vs. “generative”.

What does Dopamine has to do with all this? Well, it appears that current neuroscience research sentiment is that Dopamine plays a (central?) part in the above coding mechanism. That is, committing memories of choices & actions from the working buffer into the pleasure library, upon a pleasure burst, complete with rankings (assigning and updating potence levels). But what – precisely – is that role, and how exactly Dopamine does it, no one seems to be able to explain yet. At least, not that I could find.

This seems like a good point to stop for now, so I’ll end this post and wish:

Peace to all.

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Did you know…? There are more posts in this blog than are presented to you right now. It’s an attribute of the template which I can’t change.
How to see all of them?
Click on the header – the bold “The Meaning of Life and Other Vegetables” at the top. You’ll get a list (which is not complete either), with a button at the bottom to access the next list, and so on. Those go all the way back to my first post in this blog.
Enjoy Reading!