Further implications of hippocampal theory

So while on my walk today, I got to thinking about various potential implications of the hippocampal theory of time preference.

The short version if you don’t want to read yesterday’s post is that one’s degree of impulsivity/ability to plan / high or low time preference seems to be mediated by an interaction between the nucleus accumbens, which seems to a desire center, and the hippocampus, which does a lot of IQ-related tasks like learn new things and track objects through space. Humans with hippocampal damage become amnesiacs; rats with the connection between their nucleus accumbens and hipocampus severed lose their ability to delay gratification even for superior rewards, becoming slaves to instant gratification.

So, my suspicion:

Relatively strong hippocampus => inhibition of the nucleus accumbens => low time preference.

Relatively weak hippocamus => uninhibited nucleus accumbens => high time preference (aka impulsivity.)

Also, Strong hippocampus = skill at high IQ tasks.

Incentivise traits accordingly.

Anyway, so I was thinking about this, and it occurred to me that it could explain a number of phenomena, like the negative correlation between weight and IQ, eg:

Shamelessly stolen from Jayman's post.
Shamelessly stolen from Jayman’s post. As usual, I recommend it.

(Other theories on the subject: Intelligent people make lots of money and so marry attractive people, resulting in a general correlation between IQ and attractiveness; there is something about eating too much or the particular foods being eaten that causes brain degeneration.)

People generally claim that overweight people lack “willpower.” Note that I am not arguing about willpower; willpower is only a tiny part of the equation.

The skinny people I know do not have willpower. They just do not have big appetites. They are not sitting there saying, “OMG, I am so hungry, but I am going to force myself not to eat right now;” they just don’t actually feel that much hunger.

The fat people I know have big appetites. They’ve always had big appetites. Some of them have documented large appetites going back to infancy. Sure, their ability to stay on a diet may be directly affected by willpower, but they’re starting from a fundamentally different hunger setpoint.

So what might be going on is just a matter of whether the hippocampus or nucleus accumbens happens to be dominant. Where the NE is dominant, the person feels hunger (and all desires) quite strongly. Where the hippocampus is dominant, the person simply doesn’t feel as much hunger (or other desires.)

That a strong hippocampus also leads to high IQ may just be, essentially, a side effect of this trade-off between the two regions.

We might expect, therefore, to see higher inhibition in smart people across a range of behaviors–take socializing, sex, and drug use. *Wanders off to Google*

So, first of all, it looks like there’s a study that claims that higher IQ people do more drugs than lower IQ people. Since the study only looks at self-reported drug use, and most people lie about their illegal drug use, I consider this study probably not very useful; also, drug use is not the same as drug addiction, and there’s a big difference between trying something once and doing it compulsively.

Heroin and cocaine abusers have higher discount rates for delayed rewards than alcoholics or non-drug-using controls

IQ and personality traits assessed in childhood as predictors of drinking and smoking behaviour in middle-aged adults: a 24-year follow-up study (they found that lower IQ people smoke more)

Severity of neuropsychological impairment in cocaine and alcohol addiction: association with metabolism in the prefrontal cortex (Cocaine users are dumb)

HighAbility: The Gifted Introvert claims that 75% of people over 160 IQ are introverts.

Research Links High Sex Drive To High IQ, But Brainiacs Still Have Less Sex Than Everyone Else (Spoiler alert: research does not link high sex drive to IQ. Also, NSFW picture alert.)

I am reminded here of a story about P. A. M. Dirac, one of my favorite scientists:

“An anecdote recounted in a review of the 2009 biography tells of Werner Heisenberg and Dirac sailing on an ocean liner to a conference in Japan in August 1929. “Both still in their twenties, and unmarried, they made an odd couple. Heisenberg was a ladies’ man who constantly flirted and danced, while Dirac—’an Edwardian geek’, as biographer Graham Farmelo puts it—suffered agonies if forced into any kind of socialising or small talk. ‘Why do you dance?’ Dirac asked his companion. ‘When there are nice girls, it is a pleasure,’ Heisenberg replied. Dirac pondered this notion, then blurted out: ‘But, Heisenberg, how do you know beforehand that the girls are nice?'”[30]” (from the Wikipedia.)

Folks speculate that Dirac was autistic; obviously folks don’t speculate such things about Heisenberg.

Autism I have previously speculated may be a side effect of the recent evolution of high math IQ, and the current theory implies a potential correlation between various ASDs and inhibition.

Looks like I’m not the first person to think of that: Atypical excitation–inhibition balance in autism captured by the gamma response to contextual modulation:

The atypical gamma response to contextual modulation that we identified can be seen as the link between the behavioral output (atypical visual perception) and the underlying brain mechanism (an imbalance in excitatory and inhibitory neuronal processing). The impaired inhibition–excitation balance is suggested to be part of the core etiological pathway of ASD (Ecker et al., 2013). Gamma oscillations emerge from interactions between neuronal excitation and inhibition (Buzsaki and Wang, 2012), are important for neuronal communication (Fries, 2009), and have been associated with e.g., perceptual grouping mechanisms (Singer, 1999).

Also, Response inhibition and serotonin in autism: a functional MRI study using acute tryptophan depletion:

“It has been suggested that the restricted, stereotyped and repetitive behaviours typically found in autism are underpinned by deficits of inhibitory control. … Following sham, adults with autism relative to controls had reduced activation in key inhibitory regions of inferior frontal cortex and thalamus, but increased activation of caudate and cerebellum. However, brain activation was modulated in opposite ways by depletion in each group. Within autistic individuals depletion upregulated fronto-thalamic activations and downregulated striato-cerebellar activations toward control sham levels, completely ‘normalizing’ the fronto-cerebellar dysfunctions. The opposite pattern occurred in controls. Moreover, the severity of autism was related to the degree of differential modulation by depletion within frontal, striatal and thalamic regions. Our findings demonstrate that individuals with autism have abnormal inhibitory networks, and that serotonin has a differential, opposite, effect on them in adults with and without autism. Together these factors may partially explain the severity of autistic behaviours and/or provide a novel (tractable) treatment target.”

This may not have anything at all to do with the hippocampus-NA system, of course.

Schizophrenic patients, on the other hand, appear to have the opposite problem: Hyper Hippocampus Fuels Schizophrenia?:

““What we found in animal models and others have found postmortem in schizophrenic patients is that the hippocampus is lacking a certain type of GABA-ergic [GABA-producing] neuron that puts the brakes on the system,” says Grace. “What we’re trying to do is fix the GABA system that’s broken and, by doing that, stabilize the system so the dopamine system responses are back to normal, so that we can actually fix what’s wrong rather than trying to patch it several steps downstream.””

Wow, I made it through two whole posts on the brain without mentioning the amygdala even once.


Time Preference: the most under-appreciated mental trait

Time Preference isn’t sexy and exciting, like anything related to, well, sex. It isn’t controversial like IQ and gender. In fact, most of the ink spilled on the subject isn’t even found in evolutionary or evolutionary psychology texts, but over in economics papers about things like interest rates that no one but economists would want to read.

So why do I think Time Preference is so important?

Because I think Low Time Preference is the true root of high intelligence.

First, what is Time Preference?

Time Preference (aka future time orientation, time discounting, delay discounting, temporal discounting,) is the degree to which you value having a particular item today versus having it tomorrow. “High time preference” means you want things right now, whereas “low time preference” means you’re willing to wait.

A relatively famous test of Time Preference is to offer a child a cookie right now, but tell them they can have two cookies if they wait 10 minutes. Some children take the cookie right now, some wait ten minutes, and some try to wait ten minutes but succumb to the cookie right now about halfway through.

Obviously, many factors can influence your Time Preference–if you haven’t eaten in several days, for example, you’ll probably not only eat the cookie right away, but also start punching me until I give you the second cookie. If you don’t like cookies, you won’t have any trouble waiting for another, but you won’t have much to do with it. Etc. But all these things held equal, your basic inclination toward high or low time preference is probably biological–and by “biological,” I mean, “mostly genetic.”

Luckily for us, scientists have actually discovered where to break your brain to destroy your Time Preference, which means we can figure out how it works.

The scientists train rats to touch pictures with their noses in return for sugar cubes. Picture A gives them one cube right away, while picture B gives them more cubes after a delay. If the delay is too long or the reward too small, the rats just take the one cube right away. But there’s a sweet spot–apparently 4 cubes after a short wait—where the rats will figure it’s worth their while to tap picture B instead of picture A.

But if you snip the connection between the rats’ hippocampi and nucleus accumbenses, suddenly they lose all ability to wait for sugar cubes and just eat their sugar cubes right now, like a pack of golden retrievers in a room full of squeaky toys. They become completely unable to wait for the better payout of four sugar cubes, no matter how much they might want to.

So we know that this connection between the hippocampus and the nucleus accumbens is vitally important to your Time Orientation, though I don’t know what other modifications, such as low hippocampal volume or low nucleus accumbens would do.

So what do the hippocampus and nucleus accumbens do?

According to the Wikipedia, the hippocampus plays an important part in inhibition, memory, and spatial orientation. People with damaged hippocampi become amnesiacs, unable to form new memories.There is a pretty direct relationship between hippocampus size and memory, as documented primarily in old people:

“There is, however, a reliable relationship between the size of the hippocampus and memory performance — meaning that not all elderly people show hippocampal shrinkage, but those who do tend to perform less well on some memory tasks.[71] There are also reports that memory tasks tend to produce less hippocampal activation in elderly than in young subjects.[71] Furthermore, a randomized-control study published in 2011 found that aerobic exercise could increase the size of the hippocampus in adults aged 55 to 80 and also improve spatial memory.” (wikipedia)

Amnesiacs (and Alzheimer’s patients) also get lost a lot, which seems like a perfectly natural side effect of not being able to remember where you are, except that rat experiments show something even more interesting: specific cells that light up as the rats move around, encoding data about where they are.

“Neural activity sampled from 30 to 40 randomly chosen place cells carries enough information to allow a rat’s location to be reconstructed with high confidence.” (wikipedia)

"Spatial firing patterns of 8 place cells recorded from the CA1 layer of a rat. The rat ran back and forth along an elevated track, stopping at each end to eat a small food reward. Dots indicate positions where action potentials were recorded, with color indicating which neuron emitted that action potential." (from Wikipedia)
“Spatial firing patterns of 8 place cells recorded from the CA1 layer of a rat. The rat ran back and forth along an elevated track, stopping at each end to eat a small food reward. Dots indicate positions where action potentials were recorded, with color indicating which neuron emitted that action potential.” (from Wikipedia)

According to Wikipedia, the Inhibition function theory is a little older, but seems like a perfectly reasonable theory to me.

“[Inhibition function theory] derived much of its justification from two observations: first, that animals with hippocampal damage tend to be hyperactive; second, that animals with hippocampal damage often have difficulty learning to inhibit responses that they have previously been taught, especially if the response requires remaining quiet as in a passive avoidance test.”

This is, of course, exactly what the scientists found when they separated the rats’ hippocampi from their nucleus accumbenses–they lost all ability to inhibit their impulses in order to delay gratification, even for a better payout.

In other word, the hippocampus lets you learn, process the moment of objects through space (spatial reasoning) and helps you suppress your inhibitions–that is, it is directly involved in IQ and Time Preference.


So what is the Nucleus Accumbens?

According to Wikipedia:

“As a whole, the nucleus accumbens has a significant role in the cognitive processing of aversion, motivation, pleasure, reward and reinforcement learning;[5][6][7] hence, it has a significant role in addiction.[6][7] It plays a lesser role in processing fear (a form of aversion), impulsivity, and the placebo effect.[8][9][10] It is involved in the encoding of new motor programs as well.[6]

Dopaminergic input from the VTA modulate the activity of neurons within the nucleus accumbens. These neurons are activated directly or indirectly by euphoriant drugs (e.g., amphetamine, opiates, etc.) and by participating in rewarding experiences (e.g., sex, music, exercise, etc.).[11][12] …

The shell of the nucleus accumbens is involved in the cognitive processing of motivational salience (wanting) as well as reward perception and positive reinforcement effects.[6] Particularly important are the effects of drug and naturally rewarding stimuli on the NAc shell because these effects are related to addiction.[6] Addictive drugs have a larger effect on dopamine release in the shell than in the core.[6] The specific subset of ventral tegmental area projection neurons that synapse onto the D1-type medium spiny neurons in the shell are responsible for the immediate perception of the rewarding property of a stimulus (e.g., drug reward).[3][4] …

The nucleus accumbens core is involved in the cognitive processing of motor function related to reward and reinforcement.[6] Specifically, the core encodes new motor programs which facilitate the acquisition of a given reward in the future.[6]

So it sounds to me like the point of the nucleus accumbens is to learn “That was awesome! Let’s do it again!” or “That was bad! Let’s not do it again!”

Together, the nucleus accumbens + hippocampus can learn “4 sugar cubes in a few seconds is way better than 1 sugar cube right now.” Apart, the nucleus accumbens just says, “Sugar cubes! Sugar cubes! Sugar cubes!” and jams the lever that says “Sugar cube right now!” and there is nothing the hippocampus can do about it.


What distinguishes humans from all other animals? Our big brains, intellects, or impressive vocabularies?

It is our ability to acquire new knowledge and use it to plan and build complex, multi-generational societies.

Ants and bees live in complex societies, but they do not plan them. Monkeys, dolphins, squirrels, and even rats can plan for the future, but only humans plan and build cities.

Even the hunter-gatherer must plan for the future; a small tendril only a few inches high is noted during the wet season, then returned to in the dry, when it is little more than a withered stem, and the water-storing root beneath it harvested. The farmer facing winter stores up grain and wood; the city engineer plans a water and sewer system large enough to handle the next hundred years’ projected growth.

All of these activities require the interaction between the hippocampus and nucleus accumbens. The nucleus accumbens tells us that water is good, grain is tasty, fire is warm, and that clean drinking water and flushable toilets are awesome. The hippocampus reminds us that the dry season is coming, and so we should save–and remember–that root until we need it. It reminds us that we will be cold and hungry in winter if we don’t save our grain and spend a hours and hours chopping wood right now. It reminds us that not only is it good to organize the city so that everyone can have clean drinking water and flushable toilets right now, but that we should also make sure the system will keep working even as new people enter the city over time.

Disconnect these two, and your ability to plan goes down the drain. You eat all of your roots now, devour your seed corn, refuse to chop wood, and say, well, yes, running water would be nice, but that would require so much planning.


As I have mentioned before, I think Europeans (and probably a few other groups whose history I’m just not as familiar with and so I cannot comment on) IQ increased quite a bit in the past thousand years or so, and not just because the Catholic Church banned cousin marriage. During this time, manorialism became a big deal throughout Western Europe, and the people who exhibited good impulse control, worked hard, delayed gratification, and were able to accurately calculate the long-term effects of their actions tended to succeed (that is, have lots of children) and pass on their clever traits to their children. I suspect that selective pressure for “be a good manorial employee” was particularly strong in German, (and possibly Japan, now that I think about it,) resulting in the Germanic rigidity that makes them such good engineers.

Nothing in the manorial environment directly selected for engineering ability, higher math, large vocabularies, or really anything that we mean when we normally talk about IQ. But I do expect manorial life to select for those who could control their impulses and plan for the future, resulting in a run-away effect of increasingly clever people constructing increasingly complex societies in which people had to be increasingly good at dealing with complexity and planning to survive.

Ultimately, I see pure mathematical ability as a side effect of being able to accurately predict the effects of one’s actions and plan for the future (eg, “It will be an extra long winter, so I will need extra bushels of corn,”) and the ability to plan for the future as a side effect of being able to accurately represent the path of objects through space and remember lessons one has learned. All of these things, ultimately, are the same operations, just oriented differently through the space-time continuum.

Since your brain is, of course, built from the same DNA code as the rest of you, we would expect brain functions to have some amount of genetic heritablity, which is exactly what we find:

Source: The Heritability of Impulse Control
Source: The Heritability of Impulse Control, Genetic and environmental influences on impulsivity: a meta-analysis of twin, family and adoption studies

“A meta-analysis of twin, family and adoption studies was conducted to estimate the magnitude of genetic and environmental influences on impulsivity. The best fitting model for 41 key studies (58 independent samples from 14 month old infants to adults; N=27,147) included equal proportions of variance due to genetic (0.50) and non-shared environmental (0.50) influences, with genetic effects being both additive (0.38) and non-additive (0.12). Shared environmental effects were unimportant in explaining individual differences in impulsivity. Age, sex, and study design (twin vs. adoption) were all significant moderators of the magnitude of genetic and environmental influences on impulsivity. The relative contribution of genetic effects (broad sense heritability) and unique environmental effects were also found to be important throughout development from childhood to adulthood. Total genetic effects were found to be important for all ages, but appeared to be strongest in children. Analyses also demonstrated that genetic effects appeared to be stronger in males than in females.”


“Shared environmental effects” in a study like this means “the environment you and your siblings grew up in, like your household and school.” In this case, shared effects were unimportant–that means that parenting had no effect on the impulsivity of adopted children raised together in the same household. Non-shared environmental influences are basically random–you bumped your head as a kid, your mom drank during pregnancy, you were really hungry or pissed off during the test, etc., and maybe even cultural norms.

So your ability to plan for the future appears to be part genetic, and part random luck.

Remember when Liberals gave a shit about the Environment?

I miss those days.

Sierra Club Supports Path to Citizenship for Undocumented Immigrants (Yes, this is from the actual Sierra Club website):

“Today, the Sierra Club announced its support for an equitable path to citizenship for undocumented immigrants.

“The Sierra Club Board of Directors, made up of elected volunteer leaders, has unanimously adopted the position:

“‘Currently at least 11 million people live in in the U.S. in the shadows of our society. Many of them work in jobs that expose them to dangerous conditions, chemicals and pesticides, and many more of them live in areas with disproportionate levels of toxic air, water, and soil pollution. To protect clean air and water and prevent the disruption of our climate, we must ensure that those who are most disenfranchised and most threatened by pollution within our borders have the voice to fight polluters and advocate for climate solutions without fear.

“‘… America’s undocumented population should be able to earn legalization and a timely pathway to citizenship, with all the rights to fully participate in our democracy, including influencing environmental and climate policies. ‘”

Here, you might need this:


Normally I try to give people the benefit of the doubt, but I’ve heard enough people on the left lately explicitly saying that their organizations favor increased immigration because they believe those immigrants will vote Democrat/otherwise support their organizations that I’m starting to think that “import voters” is actually a Democratic strategy.

Which is cheating, BTW.

(Also, the Republican leadership wants more immigrants to keep wages down. Both sides are terrible.)

As logic goes, this is dumbass logic.

1. If the problem is that illegal immigrants can’t protest unhealthy work conditions without getting deported, then this is a good argument in favor of preventing illegal immigration, not encouraging more of it.

2. What makes them think Hispanic immigrants are suddenly going to start advocating for environmental protections, anyway? (I mean, do I have to drag out statistics here to prove that tree-hugging hippies are overwhelmingly white?)

Mexican citizens in their own country created one of the most polluted cities in the world:

Democracy: doesn't always end pollution
Mexico City

Mexico city manages to top the list of the world’s most polluted major cities:

From Air Pollution in Mexico City, by Hofmann
From Air Pollution in Mexico City, by Hofmann

Somehow, I don’t think lack of legal citizenship is the issue.

3. Population growth is one of the worst possible things you can promote if you give a shit about the environment. The Sierra Club used to understand this, back when their official policy favored population stabilization.

In other words, the Sierra Club is now explicitly advocating policies that result in environmental destruction.

Ultimately, I actually think the “they’ll vote for us!” justification is just that: a flimsy justification for doing what they want to do anyway, whether it actually squares with their other goals or not.

Which is to say, I don’t actually think the Sierra Club’s Board of Directors is delusional enough to think that increasing immigration will actually help the environment. Rather, I think the Board consists of liberals who buy into the pro-unlimited immigration propaganda that moving anywhere you want is a basic human right, and are especially interested in proving how much they love POCs, despite (or perhaps because of) working for one of the most overwhelmingly white organizations in the US. But since unfettered immigration => population growth is actually bad for the environment, some justification must be made to reconcile the two positions.

Meanwhile, about 66% of Americans actually do think Global Warming is happening, and only 15% are really committed to the idea that it isn’t.

But aside from a few people placidly saying they’re concerned about global warming, and a few people vocally responding, where is our leadership on the issue?

Al Gore seems to have had some things to say on the environment, but since he lost the Supreme Court vote, the Democratic base has turned increasingly toward more “people” oriented issues like racism, immigration, and gay marriage. And the kinds of people who care deeply about immigration, racism, and gay marriage may not happen to overlap with the kinds of people who think we should give serious thought to long-term global sustainability.

Here’s a question from the blog, “Ask a White Person: white people answering white peoples questions about race issues“:

“I got into an argument with a friend of mine who is a person of color. They were mad at me because I feel very passionately about protecting the ocean and they said that made me a bad person because I should only care about is social justice. I do care about social justice and I stand up to racism where I can, but how do I reply to that?”

From the response:

“Is client change real? Hell yeah! Is the ocean becoming a mass of plastic? Of course. But right in front of you is your friends pain.”

It’s almost like people who tend toward high time discounting don’t understand the logic of people with low time discounting.

“Since I don’t know you I also want to make sure to offer up that white people have a horrible track record of racism when discussing climate change. I am not saying this is you personally, just the system that we have created around climate issues has become its own thing and often is very racist in its approach. The way people talk about “food deserts” for example (which are almost always lower income communities of color) implies that there is not a food culture in those communities.”

Remember, if you’re concerned about the availability of fresh food in inner city communities, you’re a racist.

BTW, the presence or absence of a grocery store in downtown Detroit is not an environmental issue.

“One of the tricks here though is to keep fighting for climate justice and protecting the oceans while not ignoring your friend, and people of color, here on land. All of this shit is interconnected. The same system that is oppressing people is oppressing the ocean. … If we center black lives in our work then we will have to discuss climate issues, and the ocean. Listen to your friend and maybe what they are saying is that this type of centering in your work around oceans is needed. Maybe it is their not so subtle way of saying that they feel ignored in the larger climate and ocean movement?”

Meanwhile, Democrats are so committed to infinite immigration that openly illegal immigrants are being invited to White House Press Conferences.


Now, do whites have a great environmental track record?


But it’d be awfully nice if someone could start having one.

Redwood forest
It’d be nice to have a planet that’s nice to live on.

Man arrested more than 70 times; released again

Nicholas Limpert from Spokane has been arrested more than 70 times. Now charged again, prosecutors are working to find a way to keep a career criminal off the streets. 

His first offense? Murder, at the age of 15.

“Prosecutors told KREM 2 News on Wednesday that they plan to get tough on Limpert with his latest trial.”

“Larry Haskell, the Spokane County prosecutor, said Limpert’s history of crimes could final[ly] be catching up to him.”

70th time’s the charm, right?

“”I think every day what I could’ve done to prevent myself from getting into trouble,” Limpert told a judge.”

Not get caught; clearly this man needs to work on his skills at not getting caught.

It is possible that Limpert actually has some desire to not get into trouble, but simply lacks any ability to control his actions and act in a non-criminal manner. It is also possible that Limpert just doesn’t want to go to jail for his criminal activities. Either way, nothing’s going to change.