Fetal Pain And Neuroscience

This is a piece that I put up on Tumblr last year during the Texas fetal pain legislation. I didn’t know at the time that Tumblr is terrible for blog posts so, as we once again get into the questions of fetal pain due to the impending federal legislation, I thought it would be a good piece to bring to blog form as the discussion renews.

Note: The conversation below is neither a political nor a moral discussion. This is strictly about what nueroscience tells us about the experience of pain and how that sense of pain develops in a fetus.


Back in June 2013, a Texas GOP congressman said something about how fetuses feel pleasure and pain and was roundly mocked. The congressman was a former OB/GYN, so we know he had some experience and training with pre-born infants and I wondered how accurate his statement was.

So I turned to my brother, a published neuroscientist currently going through med school. He actually might object to being called a neuroscientist since he doesn’t have a PhD, but he did years of graduate research exclusively in the field that has resulted in several peer-reviewed publications, so I feel pretty comfortable with the title.

Anyway, I asked him about it and we had a big discussion that I felt really informed my understanding of the topic. I meant to compile it into a blog post, but the mockery faded and so did my interest.

Then Salon decided they wanted to throw on their “It’s science, bitches!” baseball caps and prove that “their side” is using science while “the other side” is using nonsensical pseudoscience for dummies.

This is a thing I’ve noticed too many people like to do: Simplify the science to a point where they are conveying no valuable information or understanding (check), find a technical voice willing to confirm their bias (in this case, a second-trimester abortion provider who, I’m sure, has no dog in this fight), and generally act like second graders who found that the science textbook phrased something in such a way that they can titter to themselves and feel intellectual about their ignorance.

It’s juvenile, it’s arrogant, and people deserve to understand the complexities of the matter a little better. Journalism is supposed to do this. Actually… decent, intellectually curious human beings are supposed to do this, whether or not they work in journalism. But journalists are supposed to get paid for it and they have failed miserably to present the science here, instead giving us a pre-baked conclusion backed up by an abortion provider while yelling “SCIENCE”.

So here is my discussion with an actual neuroscientist who actually wants people to understand things that matter. Keep in mind, this discussion stems from the original congressman’s statement, not from the Salon piece.

Me: You know something about embryology, is the congressman’s statement here about fetal pleasure correct?

Bro: It’s highly inaccurate. It’s straight up wrong because of his definitions.

Me: Inform me.

Bro: Let’s back up a bit and define our terms, the words “feel,” “pleasure,” and “pain”.

“Feel” can be simply mean a response to environmental stimuli not necessarily requiring a level of processing indicative of intelligent life. For example you poke microorganisms and they can recoil because they don’t like getting poked. It “felt” that poke.

“Pain” suggests a different and higher level of processing capable of suffering in response to environmental stimuli. This is a much more complex neurological process and also much harder to cleanly define.

Me: OK. For context, the political argument on the right regarding abortion (at the moment) is “a fetus of a certain gestational age can feel pain”. So what would you suggest is a good benchmark for measuring pain (in the sense that humans or higher level organisms experience it)?

Bro: That gets way trickier. Again, our terms aren’t clearly defined in a way that I, as a scientist, can really give a “yes” or “no” answer. I don’t know whether you mean “at what point do we know something is feeling pain?” or “What level of processing is required to feel pain?” or even “What level of neurological pain processing is close enough to what we call ‘suffering’ that it would matter from a moral point of view?” 

Keep in mind that while “pain” and “response to stimuli” are commonly grouped together, they are not necessarily bound together. You can feel pain but be unable to respond to it. For example, there are cases of anesthesia awareness where a patient is fully non-responsive but also fully conscious and capable of pain. In a situation like that, the only way we know pain happened is because the patient reported it after the fact. So a lack of response to stimuli is no guarantee of a lack of pain. (for more on anesthesia awareness: http://en.wikipedia.org/wiki/Anesthesia_awareness )

If I were making a pro-life argument, I would take a similar stance as the guy in the article, although I would absolutely not use the word pleasure. Pleasure comes from a far more complex form of brain processing than pain. Take that statement out of the discussion completely.

The main issue (it seems) is that at some point a developing human is capable of processing pain. There is no difference in terms of brain processing 2 minutes before a child is born and 2 minutes after. The question then becomes when is the fetus (or pre-born infant or whatever we’re using these days) capable of processing pain. The answer is that we don’t really know. But here are the neurological boundaries for the discussion that might give us some groundwork for trying to answer that question.

Me: Hooray for philosophy.

Bro: By the way, I know this is from a neuro heavy perspective of embryology… but that’s what I got.

First, there’s response to stimuli. A fetus responds to stimuli around 15-20 weeks. We could imagine how we would feel in response to the stimuli so we might transpose our imagined experience to that of the fetus. If they respond in the same way we think we would respond, we think they feel the same way.

That’s as a result of things called “mirror neurons” that help us to enjoy watching football games cause we can imagine ourselves catch the football. It improves things like empathy/sympathy. But just because a goldfish recoils from being poked with a sharp object doesn’t mean that it processes that poking in such a way that it leaves emotional scarring for years to come. We might be emotionally scarred, but the goldfish won’t be. It feels, i.e. responds, but it doesn’t process.

Second, there’s pain. This means that it responds to *and* processes pain stimuli in a way that we do, but that doesn’t mean that it processes the experience of pain. By that I mean that we have higher processing capable of recalling, discussing, analyzing, philosophizing, considering (etc.) experiences. We can do that but a frog wouldn’t do that.

Third is the mental recall and analysis of pain. We might try to rescue someone who is in pain, because we know how pain feels and it sucks and you empathize with someone and we don’t want them to experience it. We see pain, recognize it, empathize, and respond. We’re processing the experience of pain in a recollective and complex fashion.

So that’s 3. 1. Feeling, 2. Processing, and 3. Complex processing of pain

Me: So, if I understand correctly, 1 (feeling) isn’t something we would normally care about. And the fetus does that pretty early on. 2 (processing) is something we care more about, but there’s a lot of gray area. Fetuses *probably* have that in the 20ish week range, but it’s hard to say. 3 (complex processing) is something we care deeply about but it’s pretty much impossible to say whether a fetus or even a baby under 1 month has that in a way we would recognize.

Bro: Mostly right. Processing is actually something that might not really be happening until like… a year old. It almost certainly doesn’t happen prior to birth.

With 3 you can definitely suffer. With 2 you can maybe suffer. With 1… well, if suffering occurs with that we might as well not even eat plants.

The pain line of argumentation is useless for someone who wants to focus on conception. If you want to use pain as a moral sticking point and you want to do it grounded in science, you should focus on either the grey area of 15-25 weeks or sometime around like 6 months or a year after birth. Is anyone making the case abortion should be legal at 56 weeks? If they base the right to life on pain processing, they’re going to have to give up on 38 week abortions too. At least if they want to be intellectually coherent and base their argument on science. Is that a big concern on both sides?

Me: Not usually.

Bro: OK. Well, back to the neuroscience. I’m not boring you, am I.

Me: Nope, continue.

Bro: OK, the brain is kind of like computing. A single neural connection doesn’t really mean a whole lot just like if you have one transistor that doesn’t really do a whole lot. Neurons are building blocks. When you have 100 billion, then you can build something pretty awesome. But it’s hard to attribute meaning to individual neurons.

The brain is divided by function into gyruses and sulci. Gyruses are the ridges and sulci are the folds or wrinkles. Different gyruses have different functions.

Fetuses younger than 24 weeks have almost no gyruses. Fetuses older than 35 weeks have virtually all their gyruses. The prefrontal cortex is what controls the executive function, where the mirror neurons are found, that lets us sympathize, empathize, philosophize, understand society. That’s the last to develop. We’ve got the largest pre-frontal cortex, monkeys have a good sized one and on down the evolutionary chain. Most mammals have one, while invertebrates don’t

The neurons located in a gyrus have the function that we expect it to have, so when the pre-central gyrus first forms, there we can find the motor neurons that control voluntary movement. Before the brain folds to make that ridge, there might be some of those neurons and the infant can move a little bit, but once it folds then where the neurons are ceases to be gray area where that gray matter is (or if it is present).

We can say “There’s the precentral gyrus! Well, he’s definitely processing muscle movement and that’s where it’s happening.” But the gyrus is a folding to making space for neurons that are multiplying in order to make room for them, not a magic appearing of neurons for the first time. So the folding is happening at 5 months, but the infant can start purposeful movement at 18 weeks (or right around 4 months).

Does that all help?

Me: I think so. From a medical/neurological stand point there are a couple key “dates” that we could use to determine what might be a helpful guideline for the “pain” discussion. If we want to say that newborns are people, we would have to track that concept back to at least 35 weeks.

And then there is a gray area back to about 24 weeks and then another one back to about 18 weeks based on neurological development and “what it means” in terms of pain processing.

Bro: That’s about right. 18 weeks, 24-25 weeks, 35 weeks (which is before birth, but not by a lot), and then the next major milestone to be months after birth. Those are estimates because some fetuses can be 1-2 weeks ahead or behind schedule. So if we’re going to track back to 24 weeks, we probably need to back up another 2 to cover the range of fetal development.

So to sum up, the fetus can respond to stimuli at like 8-9 weeks (recoil and movement originating in the spinal cord), it can’t process responses until 18 weeks (purposive movement originating from brain), 24-25 weeks you’ve got significant differentiation going on, and by 35 weeks we can actually identify the part of the brain where experiences are processed. We’re talking not just stimuli, but actual complex and higher thinking.

That’s why calling it “pleasure” or “pain” at 15 weeks is a little bit misleading, because the processing of the stimuli for the fetus at 15 weeks is very very different from how we would understand pleasure or pain. The neural processing might be closer to the response a fish would have to being poked. It would swim away.

Please keep in mind, it’s not a scientists job to make moral decisions. It’s our job to figure out how something works, not to say what it means.

I could say that the neural processing of a grown pig or a cow is capable of the same degree of executive functioning as an infant of say… 6 months, but that doesn’t mean we should stop eating meat or that we should start eating babies. A good scientist will not say “This is what happens, so therefore we have a moral imperative to do that.” He or she will merely describe the phenomena as it is observed. So don’t interpret this to mean “there is no moral issue with a 14 week abortion because they don’t process pain” or “we have a greater moral obligation to a 3 year old monkey than to a newborn infant because the monkey processes pain in a more complex way”. Pain is obviously only one component of the moral discussion here.

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