Anthropology.net

From Nobel Intent comes news of a discovery in the Mendelian genetics of Mirror Movements, a condition that causes people to involuntarily move both sides of their body when they intended to only move one.

Aside from being medically relevant, interesting on a population genetics level, and involved an Iranian family, it also caught my eye because about 3 weeks ago we covered the implications of DCC (deleted in colon cancer gene, I know — very clever!) mutations in my pathology course. DCC mutations are found in the sequence of events that lead up to a special type of familial adenomatous polyposis (FAP), known as Gardner syndromes.  These colon cancers occurs primarily on the left or descending colon. The morphology of FAP cancers lead to a napkin ring like constriction of the colon that present as alternating bouts of diarrhea and constipation. What makes them unique from other FAPs is that they have present with extracolonic manifestation, like bone cancers.

The DCC gene is on the long arm of chromosome 18. I know that it is a cell surface protein responsible for cell-to-cell and cell-to-matrix adhesion. Normally when cells proliferate, they squeeze up on each other and DCC works via contact inhibition to signal a stop in proliferation because conditions are getting too cramped. Therefore, if DCC is deleted, contact inhibition is lost and cell loses ability to proliferate, yielding a dysplastic growth.

Genbank classifies this gene as one that encodes for a netrin 1 receptor, which I did not know before I read this post. I find this really interesting in the relevance of DCC to Mirror Movements. Dr. John Nicholls,of SISSA in Trieste, Italy,  the dude for neurodevelopment, guest lectured my neuroscience course during my second term of medical school last year. I remember him describing netrins as a class of axon guiding proteins that functioned during growth and development. The hallmark experiment I remember him citing was the Oster, et al., 2004, where ganglion cell axon pathfinding in the retina and optic nerve was guided by netrin signals.

It seems that in Mirror Movements, the mutation in DCC prevents it from helping,

“nerve cells on one side of the spinal cord to stay on that side as they extend processes up and down the developing spine…. Because the protein is malformed, the body develops neural connections that route one-sided connections to both sides, producing the mirrored activity.”

I don’t have access to Science unfortunately to research the demographics of the particular SNP they discovered… So I can’t tell you of the gene frequencies… But if anyone does have access to the paper, and doesn’t emailing me, I’ll be very grateful. I love these sorts of discoveries where I learn something new and integrate what I’ve learned the past year and half of medical school!

Srour M, Rivière JB, Pham JM, Dubé MP, Girard S, Morin S, Dion PA, Asselin G, Rochefort D, Hince P, Diab S, Sharafaddinzadeh N, Chouinard S, Théoret H, Charron F, & Rouleau GA (2010). Mutations in DCC cause congenital mirror movements. Science (New York, N.Y.), 328 (5978) PMID: 20431009

Following on from a recent post which linked to the Neuroanthropology website, I want to give brief mention to a neuroscientist by the name of David Eagleman, his research into synaesthesia and an excellent book he published earlier this year, ‘Sum – Forty Tales from the Afterlives’, a pocket-sized tome bristling with a glittering array of thoughts, ideas and speculations about what gods, afterlives and ourselves might or could never be, how we know we even exist or are merely re-living a seamlessly reconstructed version of one or more past life-times.

I first came across Eagleman on this podcast from ABC Radio’s ‘All in the Mind’, hosted by Natasha Mitchell, and which is available, complete with transcript here, and from which this is the introduction:

Imagine if I gave you a glass of milk and it tasted blue to you, or if your partner’s voice just felt like a wonderful golden brown, the colour of buttery toast? What if the number two and letter J conjured up the shade of letterbox red, or the name Derek tasted like earwax? Or whenever you heard music, a kaleidoscope of colours exploded inside your head; different tones and textures for different notes. Vladimir Nabokov was one, so is artist David Hockney, in fact one in a hundred of us could be a person with synesthesia, the surprising cross-wiring of the senses in the brain.

My guest today heads up one of the top centres in synesthesia research based at Baylor College of Medicine in Houston. By day he’s a leading neuroscientist but by night he writes novels, and he’s just been in Australia to perform with Brian Eno at the Sydney Opera House a piece based on his totally intriguing new novel called Sum: Forty Tales from the Afterlives. So meet the energetic David Eagleman.

From later in the show, we hear a few more words on the extraordinary phenomena known as synaesthesia, which we learn is surprisingly prevalent in modern human populations:

…synesthesia is a condition that about one per cent of the population has, and some researchers have estimated that there are maybe 152 reported forms of synesthesia. They have a mixture of the senses, so for example if you have synesthesia you might hear music and it causes you to physically see colours, or more common versions are things like the numbers and letters of the alphabet having colours, or textures or shapes, or genders or personalities. You might taste something and it makes you feel like you’re feeling something on your fingertips, or you might hear something and that puts a taste in your mouth.

For one synesthete, for example, whenever he hears the name Derek it tastes like earwax to him, it puts the taste of that in his mouth. And for other people, you know for different words, it puts the taste of cinnamon in their mouth, or some metallic taste in their mouth and so on. It’s not just that they’re being silly or metaphorical or artistic, it’s actually that there’s cross-wiring in their brains so that from the parts of their brain that care about hearing, and the parts or their brain that care about taste, there’s a little bit of cross-talk going on, so particular auditory experiences will trigger gustatory experiences.

There are many different forms of synesthesia but what they all have in common is that they represent a blending of the senses. And it used to be thought that this was very rare but we now know that it’s really quite common, it’s at least one per cent of the population. So to come back around to your question, because of this increased cross-talk in the brain it has been suggested that maybe synesthesia is related to creativity and metaphor, because essentially that’s what it is for somebody to be very creative or to speak in metaphor, is to find parallels across different domains in the brain.

I’m not sure to what extent this a trait that applies only to our modern selves, or whether synaesthesia is something we’ve inherited from our archaic past – did Neanderthals or H. heidelbergensis or even H. erectus experience these weird fluctuations in their neural circuitry, and if so, to what extent if any has this impacted on speech, language, numeracy or even seemingly irrational belief systems which incorporate divine and omniscient beings living in abstract realms to which our souls are said to migrate shortly after our mortal demise? Do other primates share this with us, or are our own brains unique in that only our particular neural configurations are capable of fusing disparate functions into unexpected reconstructions of what seems real to us?

On that subject, here’s a quick look at some of the content in the book ‘Sum‘, which receives a fair amount of coverage elsewhere in the show – for example, this on consciousness, and by default, the concept of creation:

Questions like how consciousness comes about, how do you ever string together tens of billions of pieces and parts and get something out of it that has private subjective experience.  So if I were to hand you billions of Tinkertoys, you know those little toys you put together, and you start hooking them up so that when you touched this, that happens and so on. At what point would you add one more Tinkertoy and say ah, now this is having conscious experience?

We don’t even know what the theory would look like on that. I mean here’s another way of looking at it. When I was a child I absolutely expected that by the time I was this age we would have robots, that we would have C3PO serving our dinner and cleaning my room and so on. The best we have is the Roomba vacuum cleaner, and it turns out that things like intelligence is really, really hard to figure out. and even things like computer vision is very, very difficult.

Without our specific brand of consciousness it seems improbable that any complex living creature like our selves would be able to even conceive of a grand Creator, Architect, Programmer or Technician, but there is no doubt that such ideas are by now almost indelibly imprinted on our mind-set. However when it comes to describing the type of god or afterlife that many people believe in, their depictions tend to be somewhat workaday, and to a great extent moulded by models that have been portrayed by our families, religious educators and the clergy:

So when I sit next to people on aeroplanes and I ask them what their opinion is on whether there’s a God, or what they would look like, or what an afterlife would look like, it turns out there’s such a lack of creativity, everybody just says whatever their parents have told them. So this book is all about really mentally stretching on spatial scales and ideas of gender and number and all sorts of things.

And mentally stretching such ideas is exactly what this book does – whether you’re a confirmed atheist, a devout agnostic or fully subscribed believer, all the short stories in this book should give you pause for thought and more than a moment or two of inner reflection – indeed we’re told that the book has been equally well received from many quarters of the religious divide, no mean feat for such a book, especially in these days of entrenched fundamentalism that everywhere abound. Here’s a quick look at some of the ideas Eagleman offers up for consideration:

If you stopped someone on the street and said, ‘Hey, what do you think the afterlife is about?’ Of course everybody just has in their mind whatever their parents or their community has told them, and when you really start putting those ideas under the spotlight, what you discover is they’re ridiculous. So for example the one where God is getting frustrated in having to do this binary categorisation into good and evil. it’s a perfect example of how goofy the story is because people are much more multi-dimensional than that, they are much more complex than that.

And so in that story God decides to sort of revolt against that structure that she had set up and she instead invites everybody to come into Heaven and to be a part of Heaven. And what ends up happening actually if I can just read the last line here: ‘So she brings everyone to Heaven and everyone’s achieved true equality and the communists are baffled and irritated because they have finally achieved their perfect society, but only with the help of a God in whom they didn’t want to believe.

The meritocats are abashed that they’re stuck for eternity in an incentiveless system with a bunch of pinkos. The conservatives have no penniless to disparage, the liberals have no downtrodden to promote, so God sits on the edge of her bed and weeps at night because the only thing everyone can agree upon is that they are all in Hell.

Eagleman is also featured in a May 2009 edition of another podcast, ‘Little Atoms’, hosted by Neil Denny, and if you want to grab a copy of the book, for yourself or deserving other(s), there are two main options – you can for example order it online from places like Amazon and numerous other digital outlets.

If however, to paraphrase Matt Haynes, editor of, and writing in the latest print edition of ‘Smoke – A London Peculiar’ you believe “electricity is nothing but a demented cavalcade of charged particles over which no human could ever hold dominion”, just visit your local book-store instead, and they’ll take things from there.

Wired Science shared some news of an interesting panel titled, “What it means to be human” held at this year’s World Science Festival in New York City. This week, we saw Michael Tomasello’s take on this question. Last month there was the What Makes Us Human conference. We’ve also read Marc Hauser’s postulates.

Wired Science has summarized some of the panel speaker’s ideas, here they are, and they are almost all wrong:

Marvin Minsky, artificial intelligence pioneer: We do something other species can’t: we remember. We have cultures, ways of transmitting information.

Daniel Dannett, cognitive scientist: We are the first species that represents our reasons, and can reason with each other. “The planet has grown a nervous system,” he said.

Renee Reijo Pera, embryologist: We’re uniquely human from the moment that egg and sperm fuse. A “human program” begins before the brain even begins to form.

Patricia Churchland, neuroethicist: The structure of how the human brain is arranged intrigues me. Are there unique brain structures? As far as we can understand, it’s our size that is unique. What we don’t find are other unique structures. There may be certain types of human-specific cells — but as for what that means, we don’t know. It’s important not only to focus on us, to compare our biology and behavior to other animals.

Jim Gates, physicist: We are blessed with the ability to know our mother. We are conscious of more than our selves. And just as a child sees a mother, the species’ vision clears and sees mother universe. We are getting glimmers of how we are related to space and time. We can ask, what am I? What is this place? And how am I related to it?

Nikolas Rose, sociologist: Language and representation. We are the kind of creatures that ask those questions of ourselves. And we believe science can help answer. We’ve become creatures that think of ourselves as essentially biological — and I think we’re more than biological creatures. I’m not sure biology has answers.

Ian Tattersall, anthropologist: It’s not “what is human,” but what is unique: our extraordinary form of symbolic cognition.

Francis Collins, geneticist: What does the genome tell us? There’s surprisingly little genetic difference between human and chimpanzee. Yet clearly we’re different. There’s brain size and language. A language-related gene, FoxP2, evolved most rapidly in the last few million years. How did we develop empathy? Appreciate our mortality? And we should admit that there are areas that might not submit to material analysis: beauty, inspiration. We shouldn’t dismiss these as epiphenomenal froth.

Harold Varmus, physiologist: Intrigued by our ability to generate hypotheses and make measurements.

Paul Nurse, cell biologist: Is excited about the ability of science to answer this question.

Antonio Damasio, neuroscientist: The critical unique factor is language. Creativity. The religious and scientific impulse. And our social organization, which has developed to a prodigious degree. We have a record of history, moral behavior, economics, political and social institutions. We’re probably unique in our ability to investigate the future, imagine outcomes, and display images in our minds. I like to think of a generator of diversity in the frontal lobe — and those initials are G-O-D.

Marvin Minsky is wrong to say that humans are unique with being able to remember. Ravens/crows, elephants, great apes, etc. have shown remarkable abilities in remembering information. Minsky is also wrong in implying our culture, ways of transmitting information, are unique to humans. Lots of non-human primates, such as chimpanzees have been documented in transmitting information and having distinct rituals.

Daniel Dannett is wrong to say that, ‘we are the first species that represents our reasons, and can reason with each other.’ Reasoning is commonly defined as the cognitive process of looking for reasons for beliefs, conclusions, actions or feelings. A 2005 column written by Carl Zimmer in New York Times, summarized how chimpanzees exhibit a better understanding of cause and effect than human children.

Renee Reijo Pera, isn’t necessarily wrong in saying a unique “human program” begins before the brain even begins to form, because aspects of human development has to be fundamentally different for humans to become a different genus from other apes. But there is a lot of conservation in the development of vertebrates.

Patricia Churchland is right to say the size of human brains are unique. Recently some unique structural differences have been really studied in depth, such as the wiring of the human arcuate fasciculus. I will be really interested to find if there might be certain types of human-specific cells, but I imagine it will be a pretty monumental effort to morphologically and genetically compare every type of brain cell. It will be done though, I am sure of it.

Jim Gates is wrong to say humans are unique in the ability to know our mothers. Many species know their mothers and are conscious of more than themselves. I won’t review them all, it is pretty well studied. Gates is right and wrong at saying we’re unique in asking metaphysical questions, like, “what am I? What is this place? And how am I related to it?” It is hard to really discern if humans are the only ones asking these existential questions, but apes that use sing-language or lexigrams have been able to answer this question at a very basic level.

Nikolas Rose‘s thoughts are out-there. Language and representation are not uniquely human. Many non-human animals have been shown to communicate in unique ways. For example, orca pods have been found to have unique vocalizations that are not understood by other orcas outside of the pod. Captive chimpanzees have also been found to voice unique vocalizations to certain foods. Rose also brings up some metaphysical aspects, which I have just outlined are both right and wrong.

I find that there’s only one anthropologist on the panel, Ian Tattersall, extremely ironic considering they are asking a very anthropological question. Tattersall says our extraordinary form of symbolic cognition is unique. I can’t say definitively that he’s wrong in stating that, but chimpanzees from Gombe have been documented to show some reverence for nature, which is a very symbolic behavior. Read more from Barbara King.

Francis Collins, my favorite creationist geneticist, mentions human brain size and language as unique traits. He’s not wrong in brain size, human brain size is uniquely different from other animals, but so is a horse’s brain from that of other animals. As outlined before, language is not a uniquely human trait. Other animals have been documented to communicate and transmitted knowledge in unique forms. Given Collins’ recent vocal defection to the dark side, I’m not surprised he’s reducing epiphenomenal associations and raising the spiritual question.

Harold Varmus is intrigued by our ability to generate hypotheses and make measurements. I don’t really know what Varmus is suggesting, my best guess is that he thinks that humans are unique in problem solving and trial and error, which is wrong. Non-human animals are excellent problem solvers. While other animals don’t write up reports and publish them in Science or Nature, they do have ideas whose merit requires evaluation. Take the example of the raven who wants to open a nut. The raven most certainly has an idea, to drop the nut from high up in flight, and have the force of gravity coupled with the impact of the nut to the ground to open it up. To act upon this idea, the raven must inherently evaluate each failure and success, ultimately testing the hypothesis and measuring how effective the idea is.

Paul Nurse really didn’t give much to work with. I too am interested in how science can answer this question. I wish he was more forthcoming with his thoughts, even if they are wrong.

Antonio Damasio mentions that language is unique. I already outlined how this is wrong. He instills the human religious and scientific impulse are unique. I also already shown how chimpanzees have been documented to be somewhat spiritual, and that other animals have ‘scientific’ ways of solving problems. Damasio also brings up aspects of Tomasello theory — our ability to imagine our social organization and institutions. I won’t comment on his idea that the diversity of the human brain’s frontal lobe was designed by ‘G-O-D.’

I’m kinda surprised that this paper, “A study on the correlation between IL1RAPL1 and human cognitive ability,” hasn’t made many waves in the press nor in the blogosphere. Aside from being controversial, it is a pretty fascinating study. But, I’m not completely shocked many have abstained from mentioning it… Like the genetics of race, the genetics of intelligence is a topic many researchers aren’t willing to bet their academic careers on. Why? Because, it has been source for some pretty knee-jerk reactions.

Don’t believe me?

Remember what James Watson said last fall? To save grace, I’m not gonna reiterate his words… But I will mention that the consequences of Watson’s commentary are rather unforgettable. He lost a very prestigious career, and ended his successful reign in science on a bad note. I’m not defending beliefs like Watson’s, especially because what he said was expressed as subjective, inflammatory conjecture more than anything else, but I am curious about looking into how genetic predispositions affect intelligence and cognition.

I’ve done some reading on the topic and started many discussions about this topic, bringing up the correlations of higher than normal intelligence and the higher than normal incidences for many genetic diseases (like Tay-Sachs and hemophilia) in in Ashkenzai Jews as a case study. Time and time again, discussions have been shunned down. I’ve wondered why and I’ve come to think that people just don’t want to engage in this train of thought because of the possible repercussions it has. I worry that it has more to do with being politically correct than anything else.

That all being said, I’m very excited to have stumbled across this current paper from Dienekes. I wouldn’t have found it if it weren’t for his post. As you can tell from the title, this paper focuses on a correlation between a gene and cognition in humans. Please note how the authors are all Chinese academics, seems like folk in China people aren’t afraid to research this topic.

Anyhoot, the gene of interest, IL1RAPL1, is believed to function in binding of a kinase to a receptor. On Monday, I took an exam on this subject, looking into all the known different signal transduction mechanisms and receptor kinases were a major part of the test. Kinases are special proteins, enzymes that phosphorylate other proteins. In most common terms, a phosphorylated protein is an active one. Receptor kinases span the membranes of cells and receive extracellular stimulus to activate intracellular proteins. L1RAPL1 is expressed in muscle and brain tissue.

Previous studies have shown that individuals who have deletions or inversions of L1RAPL1 have a form of mental retardation. This indicates an important signaling pathway involved in cognition is lost when L1RAPL1 is knocked out, which is what got this group of academics to hone in on L1RAPL1 as a gene linked to cognition. To date, there has not been an investigation on the impact of the alleic variants of L1RAPL1 on cognition, which is the scope of this paper. The paper specializes in looking at relationship of L1RAPL1 polymorphisms (two microsattelites and two SNPs) with intelligence in population of Chinese kids. They also extended this study by looking a the effects of the polymorpisms on rats.

In their sample, the L1RAPL1 of 332 children (50:50 male to female), aged 5-14 years old, was screened. The genotype of each child’s L1RAPL1 variant was identified using PCR. In the population, roughly 90% were heterozygotic in the DXS1218 microsattelite variant of L1RAPL1 . Microsattelites are simple repeats of nucleotides in a sequence of DNA, I outlined one way they come about here. The other microsattelite, DXS9896 was present as heterzygotic alleles in 87% of the kids.

Two SNPs are also looked at. 89% of the kids had an A nucleotide in the rs6526806 SNP, where the other 11% had a G. 42% of the kids had one version of the rs12847959 SNP, the other 58% had another version. The authors did not mention what effect these polymorphisms had on the gene, but did indicate they all fall in the intron of the gene — a non-coding region that is spliced out.

The kids were asked to take several cognitive tests that tested their memory, concentration, perception, and verbal abilities. Three of the polymorphisms listed above had effects on memory and concentration. Those that had longer DXS1218 microsattelite variants had lower IQ scores. Similarly, kids with longer DXS9896 mircosattelites also had lower IQ scores. One of the SNPs, rs12847959 showed that individuals that had the CC genotype in the SNP had higher IQ scores compared to those that had the CG genotype. The p-values for all were pretty strict, suggesting that the differences are statistically significant.

I find the results pretty cool. Those with longer introns seem to have reduced IQ scores. Those with a difference in 1 base pair also seem to have differences in IQ scores. Now, what do lower IQ scores have to do with intelligence? Can we say low IQ scores equal dumber people? Many people will say no. IQ tests have often been criticized for not being an adequate screens of intelligence, but they are one of the only ways to systematically and uniformly exam some degree of memory, concentration, perception, and verbal abilities. I find the use of them kinda flawed because the children screen in this study were from different ages, if they all came from the same age group, I would say there would be more structure. I know I was much more intelligent at age 14 than I was at age 5… my parents may disagree though.

I want to also outline that L1RAPL1 is one of the 8,000 or so genes expressed in the human brain, all of which have some function the brain and ultimately in cognition. Thus, intelligence is very much an epistatic trait and we can’t just say alleles of L1RAPL1 are the only player in determining cognitive abilities. Perhaps a wider genome wide association/linkage disequilibrium study will begin to identify all the genetic players affecting intelligence.

GAO, X., XI, G., NIU, Y., ZHANG, S., FU, R., ZHENG, Z., ZHANG, K., LV, S., HE, H., XUE, M. (2008). A study on the correlation between IL1RAPL1 and human cognitive ability. Neuroscience Letters DOI: 10.1016/j.neulet.2008.03.084

Robert Stainton at the University of Western Ontario and Jessica de Villiers of The University of British Columbia have recently conducted a study which aims to measure and define pragmatic capabilities of autism patients, specifically those with Autism Spectrum Disorder, or ASD. Previously, one of the defining features of ASD patients was the deficiency or absence of pragmatic systems, particularly the ability to understand and use language appropriately by societal standards. ASD interferes with the ability to utilize language in practice, interfering with systems such as Entailment, Deixis, Implicature, and Presupposition. As a result, ASD patients have difficulty understanding sarcasm, irony, and abstract language.

According to Stainton, some ASD patients have shown no difficulty in understanding and using literal pragmatic systems, such as reference to specific media in nondescript terms. Although these patients are unable to grasp abstract systems such as metaphors, they show potential in literal pragmatics.

These researchers do not contest the well-established claim that people with ASD have difficulty with non-literal pragmatics, such as metaphors (“Juliet is the sun”) or irony/sarcasm (“Boy, is that a good idea”). They have, however, found that many speakers with ASD do not show the same difficulty with literal pragmatics. An example is the phrase, “I took the subway north” from a transcript of a conversation with a research participant with ASD. The use of the word “the” could indicate there is only one subway in existence going north. “The subway” could also be referring to a subway car, a subway system or a subway tunnel. Taking account of the context and the listener’s expectations, however, the individual using the phrase was able to convey the specific meaning he intended. That is, he used pragmatics effectively.

As autism is one of the most difficult neurological disorders to understand, Stainton’s research provides an important benchmark to its scientific comprehension. The breakthrough in noting ASD patient understanding of literal pragmatics has lead to the development of a rating scale of pragmatic abilities which can be used for clinical assessment. Considering the mysterious nature of autism, multidiciplanary approaches such as Stainton’s may become the standard for research in the field.

Almost all primates live in groups with an observable and definable social hierarchy, and humans aren’t an exception. We may overlook it in our day to day lives, but every so often it becomes evident that we interact best when we understand the pecking order. The social brain hpyothesis argues that the cognitive demands of living in complexly bonded social groups selected for increases in executive brain. Two new papers in the current issue of the journal Neuron investigate this phenomenon by looking at the activity in specific regions of the brain, like the striatum, which reflects a common signal of reward in both the economic and social domains.

The research was conducted by researchers at the National Institute of Mental Health. fMRI was used to monitor the activity of the brain of 72 participants who were playing an interactive computer game for money. From this press release,

“They were assigned a status that they were told was based on their playing skill. In fact, the game outcomes were predetermined and the other “players” simulated by computer… Participants intermittently saw pictures and scores of an inferior and a superior “player” they thought were simultaneously playing in other rooms.

Although they knew the perceived players’ scores would not affect their own outcomes or reward –and were instructed to ignore them – participants’ brain activity and behavior were highly influenced by their position in the implied hierarchy.”

Several interesting observations where made when the researchers compiled all the fMRI data. For example, the striatum showed activity in a situation where a rise or fall in rank was a possibility as much as it did to the monetary reward. The stratium is a critical part of the brain where dopamine is regulated, and a previous study investigated the genetics of dopamine and the linkage it had to agressive social behaviors. Overall, this observation implies that social status is highly valued in our subconscious minds, even as much as money. The press is gorging itself on this sound bite, they just love it when something as complex as social hierarchy and brain functions are reduced to something as simple as gaining money.

Another interesting observation involved subjects that were presented a ‘superior competitor’ in the game. When that happened, it triggered activity in,

“an area near the front of the brain that appears to size people up – making interpersonal judgments and assessing social status. A circuit involving the mid-front part of the brain that processes the intentions and motives of others and emotion processing areas deep in the brain activated when the hierarchy became unstable, allowing for upward and downward mobility.”

Also when the player preformed better than any superior competitors, another area towards the front of the brain which controls planning was activated. In contrast, when the player did worse than an inferior competitor different activity was shown in centers of the brain associated with emotional pain, frustration, and stress. Pretty cool.

One last cool results was associated with players who were at the top of the hierarchy, not only did they say they had a more positive experience but more activity was associated in the emotional pain circuitry when they perceived an outcome that could drop them down in rank.

These results kinda thwart any Utopian anarchists out there. This data shows that our brain’s hierarchical consciousness seems to be ingrained in the human brain, so much so that there are distinct circuits activated by concerns over social rank.

Coinciding with these two studies is this short little paper in the latest Nature investigating the genetics and expression of Neuropeptide Y (NPY). Neuropeptide Y is just that a peptide that functions as a neurotransmitter, it is involved in regulation of energy balance, memory and learning. In mice and monkeys, it has been observed that stress stimulates the expression of this gene product. That’s not very surprising because Neuropeptide Y alters adrenergic receptors, the ones that bind adrenaline and noradrenaline, two stress hormones. As seen in the above results, stress is an important behavioral response in social hierarchy.

Anyways the new Nature study finds that,

“haplotype-driven NPY expression predicts brain responses to emotional and stress challenges and also inversely correlates with trait anxiety… Lower haplotype-driven NPY expression predicted higher emotion-induced activation of the amygdala, as well as diminished resiliency as assessed by pain/stress-induced activations of endogenous opioid neurotransmission in various brain regions. A single nucleotide polymorphism (SNP rs16147) located in the promoter region alters NPY expression in vitro and seems to account for more than half of the variation in expression in vivo. These convergent findings are consistent with the function of NPY as an anxiolytic peptide and help to explain inter-individual variation in resiliency to stress…”

Like I said above, I’m pretty sure we’ve all had experiences where we felt threatened by inferior individuals and we’ve all had the glee when we thought we were at the top of our game. The fMRI study has shown what areas of the brain are active in these situations, and the genetics of NPY indicate how the allelic differences of NPY affect stress responses. All in all, I’m impressed with these trio of papers. They illuminate a lot about how we subconsciously process social hierarchy, which is a very human thing.

Zhou, Z., Zhu, G., Hariri, A.R., Enoch, M., Scott, D., Sinha, R., Virkkunen, M., Mash, D.C., Lipsky, R.H., Hu, X., Hodgkinson, C.A., Xu, K., Buzas, B., Yuan, Q., Shen, P., Ferrell, R.E., Manuck, S.B., Brown, S.M., Hauger, R.L., Stohler, C.S., Zubieta, J., Goldman, D. (2008). Genetic variation in human NPY expression affects stress response and emotion. Nature, 452(7190), 997-1001. DOI: 10.1038/nature06858

Despite the fact that I’ve seen some really impactful primate related research lately, I’ve completely neglected updating Primatology.net with it. I can’t believe it has been almost three months since I’ve posted there! I should really resume posting there. Actually, I was considering putting up this following blog post over there, since it has to do with differences in neuroanatomy of the primate brain… but because these comparative studies are in the context of identifying specific architectural differences in the human brain related to language, I think posting it here is more fitting.

If you’re a reader of Neurophilosophy, you may have an idea of what research I’m referring too, the new Nature Neuroscience paper from James Rilling and team. Before I jump into this paper, “The evolution of the arcuate fasciculus revealed with comparative DTI,” please let me share another recent paper that gives some introduction about what I’m gonna talk about.

See earlier this month, Current Biology published a paper, “Communicative Signaling Activates ‘Broca’s’ Homolog in Chimpanzees,” where researchers not only confirmed that the Broca’s area as an important area of the human brain for language comprehension, but also chimpanzees have similar activity in the homologous area of their brains when communicative signals are produced or heard. The Broca’s area has long been thought to be one of the specialized functional areas of the brain for language comprehension. In fact was discovered almost 150 years ago by a physician named Pierre Paul Broca, who conducted an autopsy of patient with a speech deficit. Broca was able to determine the patient had a syphilitic lesion in the left cerebral hemisphere and identified this area as his namesake.

If you’ve heard anything about Broca’s area, it larger in the left hemisphere of the brain. Comparing activity levels between the two hemisphere, during language-related tasks, have shown the left hemisphere Broca’s area is more active. That’s due to the lateralization of the brain, which I’m sure you’ve heard of.

Anyways, the results of this study have important implications in figuring out the functional and structural differences of the human and chimpanzee brain. Why? Well, for starters, the linguistic abilities of humans have been thought to be unique to us for a while. This is a really big misconception because research on signing apes and other communicating animals, have begun to show us that we’re not alone in our abilities to symbolize information and exchange it by way of complex sound and gesture.

In order to investigate the differences of the activity between Broca’s areas in humans and related structure in chimpanzees, Taglialatela et al., put three chimpanzee subjects in PET and fMRI machines and stimulated to vocalize by putting treats just out of their reach. They then recorded the activity of the subjects would vocalize in frustration. They were able to see the very same the neuroanatomical structures associated with the production of communicative behaviors in humans, fire in chimpanzees.

Now, of course that doesn’t mean chimpanzees are gonna be reciting Shakespeare anytime soon. This leads me to the first paper I mentioned today, the one from Rilling and crew. Rilling et al., did a comparative anatomical study on the structure of arcuate fasciculus, a large white matter tract, in humans, chimpanzees and macaques. The arcuate fasciculus functions as a linker between Broca’s area and another language associated area of the brain, Wernicke’s area. The researchers used diffusion tensor imaging (DTI), a type of noninvasive medical imaging that’s a lot like MRI but it compares and contrasts the local characteristics of water diffusion within tissues.

While the arcuate fasiculus of the rhesus macaque, the chimpanzee, and the human linked up to the frontal cortex — including with Broca’s area, it was observed that the human arcuate fasiculus is much larger. It more spreads deep into the middle temporal lobe, leaving the classical Wernicke’s area. In chimps, the arcuate fasciculus made very superficial connections to the temporal cortex regions homologous to Wernicke’s area. Macaques showed a much lower extend of this integration. Rilling commented,

“We know from previous functional imaging studies that the middle temporal lobe is involved with analyzing the meanings of words. In humans, it seems the brain not only evolved larger language regions but also a network of fibers to connect those regions, which supports humans’ superior language capabilities.”

This following diagram was published in Rilling et al.’s paper and illustrates their results:

So from these two papers, the evolution of specialized language areas maybe active in both chimpanzee and human brains but as the human brain diverged from other primate counterparts, major re-wiring at the arcuate fasciculus accompanied the massive expansion of brain size. Ultimately the area that is associated with understanding word meaning, Wernicke’s area, has been strongly connected with Broca’s area.

Rilling, J.K., Glasser, M.F., Preuss, T.M., Ma, X., Zhao, T., Hu, X., Behrens, T.E. (2008). The evolution of the arcuate fasciculus revealed with comparative DTI. Nature Neuroscience DOI: 10.1038/nn2072

TAGLIALATELA, J., RUSSELL, J., SCHAEFFER, J., HOPKINS, W. (2008). Communicative Signaling Activates ‘Broca’s’ Homolog in Chimpanzees. Current Biology, 18(5), 343-348. DOI: 10.1016/j.cub.2008.01.049

Michael Callahan of Ambient Corp. in Champaign, Ill. and the University of Illinois has recently introduced The Audeo, a thought-to-speech interfacing device which acquires and converts neurological signals into vocalizations. The device allows users to communicate with a computer much in the way voice recognition software does. However, instead of encrypting wave patterns detected in recorded utterances, The Audeo acquires and discerns individual words from neurological signals produced by the intent to vocalize.

The Audeo is being developed to create a human-computer interface for communication without the need of physical motor control or speech production. Using signal processing, unpronounced speech representing the thought of the mind can be translated from intercepted neurological signals. By interfacing near the source of vocal production, the Audeo has the potential to restore communication to people who are unable to speak. The proposed solution is a featherweight wireless device resting over the vocal cords capable of transmitting neurological information from the brain. Using data analysis, this information can be processed into synthesized speech or a menu selection capable of conveying the basic necessities of human life.

Callahan suggests possible applications of the technology, including wheelchair control for the disabled and thought-to-speech conversion for patients with ALS (amyotrophic lateral sclerosis) who lose the ability to speak over time. Demonstrations of the device can be found in the media section of The Audeo’s website as well as at the Texas Instruments Developer’s Conference Keynote. Although the prospect of retaining voices for ALS patients sounds promising, there may be a down side. If such technology were cheap and efficient, would this bear implications on sign language? As Standard American English (and other prestige dialects) continues to be commodified on 24-hour global news networks, endangering small languages, could the prospect of a new voice place signed languages in danger?

Charles Limb and Allen Braun at Johns Hopkins have recently published a study on the internal characteristics and functions of improvisation in music. The study, “Neural Substrates of Spontaneous Musical Performance: An fMRI Study of Jazz Improvisation,” uses a functional MRI to look at the neural activity of Jazz musicians, specifically pianists, during improvisation. Several controls were used to distinguish a normal predetermined musical environment from an improvisational environment. Compared to activity in the normal environment, improvisation required a completely different subset of psychological processes which were generated independently of central processes.

Such a pattern may reflect a combination of psychological processes required for spontaneous improvisation, in which internally motivated, stimulus-independent behaviors unfold in the absence of central processes that typically mediate self-monitoring and conscious volitional control of ongoing performance. Changes in prefrontal activity during improvisation were accompanied by widespread activation of neocortical sensorimotor areas (that mediate the organization and execution of musical performance) as well as deactivation of limbic structures (that regulate motivation and emotional tone).

Improvisation seems to be one of the most mysterious aspects of the linguistic processes at play during musical performance. This study is of particular pertinence to the communicative aspect of performance as Jazz musicians (et al) actively communicate in abstract and specific terms with each other and their audiences. Improvisation invokes a spontaneity within this communication, parallel but according to the study, independent of the central functions required to simply play a song. What might the capability to improvise say about language as a specialized phenotype?

Limb, C.J., Braun, A.R., Greene, E. (2008). Neural Substrates of Spontaneous Musical Performance: An fMRI Study of Jazz Improvisation. PLoS ONE, 3(2), e1679. DOI: 10.1371/journal.pone.0001679