Schizophrenia and plasticity/neurogenisis: a case for positive selection?

A recent study has unearthed the normal function of a gene involved in Schizophrenia susceptibility. This gene called DISC 1(Disrupted in Schizophrenia 1) is now though to orchestrate the neuronal migration process of new neurons that are created in the adult human brain.

It turns out that this gene, called disc1, makes a protein that serves as a sort of musical conductor for newly made nerve cells in the adult brain, guiding them to their proper locations at the appropriate tempo so they can seamlessly integrate into our complex and intertwined nervous system. If the DISC1 protein doesn't operate properly, the new nerves go hyper.

It is believed that the allele that raise susceptibility to Schizophrenia , also speed up the neuronal migration process. Thus, the fact, that as we progress towards more and more neoteny , and towards a brain that is plastic and undergoes neurogeneisis, even in adulthood, so too the burden of this trait- some of us who are the forerunner for this increased neurogeneisis and speedy neural migration, also have to pay the cost for that behavior.

While it may not be obvious why high-speed integration would be detrimental, Song notes that because of the complexity of the brain, timing is critical to ensure that new nerves are prepared to plug into the neural network.

Another related article , brings to light the fact that some of the genes most strongly implicated in schizophrenia susceptibility, have also been under positive selection recently. Thus, it is evident that Schizophrenia is a cost we have to play for the creativity that might result from increased learning potential vis-a-vis more and faster neurogenesis and speedy neural migration.

Several genes with strong associations to schizophrenia have evolved rapidly due to selection during human evolution, according to new research in the Proceedings of the Royal Society B (Wednesday 5 September 2007).

To me, this is further evidence for the fact that Schizophrenia is just an extreme end of a particular creative thinking style and which has as a basis differential connectivity patterns in the brain.

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Obesity: The Dopamine Connection

In a recent news article, there is a surprising revelation, that obese people have fewer dopamine receptors. The article author links this to a state akin to addiction (with amphetamine etc) as in addicted individuals too the dopamine system is involved and after prolonged usage of the drug, the dopamine receptors become less in the system.

It turns out that food also affects the brain's dopamine systems. When Volkow, who is also director of the National Institute on Drug Abuse, and her colleagues compared brain images of methamphetamine users with obese people, they found both groups had significantly fewer dopamine receptors than healthy people. Even more interesting: The higher the body mass index, the fewer the dopamine receptors -- a finding that may open the door to a better understanding of why it is so difficult for some people to lose weight and keep it off.

What role dopamine may play in obesity -- and how eating affects it -- is still to be determined. No one knows when the obese people in the study lost their dopamine receptors in the brain or if that loss could be reversed with weight loss. Are some people more susceptible to the effects of eating sugary, high-fat fare because they start out with lower levels of dopamine receptors in the brain? Or could eating those foods decrease dopamine receptors? Might food additives, preservatives and other substances also have an effect on dopamine receptors?

While several alternatives are provided above as to why this link exists, I would like to advance my own thoughts on the matter. First and foremost, I would like to speculate that when we eat something , we get a dopamine rush, and all of us carve food (get hungry) when we haven't had a food-associated-dopamine-rush for a long time. Now, if the dopamine rush that we feel, when eating, is not strong enough, we would still feel hungry. This cycle may lead to obesity. Now, from the above study it is clear, that obese people have fewer Dopamine receptors than the rest of us. thus, when they eat something, though the dopamine released in synapses may be the same as that in normal people, due to lesser dopamine receptors, they will experience a subdued dopamine rush. To compensate for this they may overeat and thus gain weight.

This theory (which seems so obvious, once stated) also explains the fact that why people on anti-psychotics sometimes gain weight as a side effect. the anti-psychotics (most of them) work as dopamine antagonist; i.e. they bind to the dopamine receptors and thus make fewer dopamine receptors available. Thus, with reduced bind able dopamine receptor sites, the food we eat, would not lead to a dopamine rush of great magnitude; thus causing overeating and weight gain.

Here, I would like to highlight that dopamine and serotonin system interact a lot, and as indicated in a previous post, those people who have low serotonin levels in brain (i.e. are depressed) also have reduced sensitivity to sweet taste. Thus, they too overeat sweet items to compensate for their reduced sweet taste. Having low serotonin and fewer D2 receptors, may be a potentially deadly condition that may lead to more food craving (especially sugary food) and may lead to obesity.

Hat tip: Center for emotional wellbeing.

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Darwinian Linguistic Evolution

There is a paper by Oudeyer and Kaplan, which discusses the evolution of languages in Darwinian terms. That is a refreshingly new (to me!) take on how languages may evolve. It applies the same Darwinian principles of heritability, variation and selection to individual phonetic words as well as associations between words and meanings.

The article makes use of computer simulations to inform their theory. Some of the take home from that article are:

• For Linguistic coherence to evolve (that is one word referring to same meaning for different agents), the replication principle most suited is whereby the most frequently encountered word is repeated and thus gets fixated in the population. This scores over the use-the-last-heard phoneme rule and use-the-phoneme-as-per-frequency-in-usage rules.
• The phonemes that can be easily confused (are liable to mutate more) with nearby phonemes get selected against and thus, selection leads to implicit evaluation whereby those phonemes that do not mutate (or mutate less) are preferred and get fixated.
• In a population with agents coming and leaving, the population flux ensures that optimal words are used and sub-optimal done away with.
• The linguistic phonemes (or words) that are used to represent concepts, break the acoustic space in such a way that their is least scope for confusion amongst the phonemes.
• A trade-off happens between linguistic distinctively and robustness. Some words are long enough that they can mutate more, but are not easily confusable. Other frequently used words are short and do not mutate easily, but if they mutate than more confusion of meaning arises.

There are more such interesting information nuggets in the paper. So why don't you have a look at the original paper itself.

Hat tip: Babel's Dawn.

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Second Life of Craig J. Phillips

No, I am not talking about the computer game Second life! This post is regarding Mr. Craig J. Phillips, who suffered traumatic brain injury and not only survived, but thrived and currently maintains a blog. He recently contacted me via commenting on this blog and I would like to quote from that and encourage readers to visit his blog and discover with him his journey that was akin to a second life.

My name is Craig J. Phillips. I am a traumatic brain injury survivor and a master’s level rehabilitation counselor. I sustained an open skull fracture with right frontal lobe damage and remained in a coma for 3 weeks at the age of 10 in August of 1967. I underwent brain and skull surgery after waking from the coma. Follow-up cognitive and psychosocial testing revealed that I would not be able to succeed beyond high school. In 1967 Neurological Rehabilitation was not available to me, so I had to teach myself how to walk, talk, read, write and speak in complete sentences. I completed high school on time and went on to obtain both my undergraduate and graduate degrees. For an in depth view of my process please read my post, http://secondchancetolive.wordpress.com/2007/02/18/my-journey-thus-far/

Through out my lifetime I developed strategies to overcome many obstacles and in so doing I have achieved far beyond all reasonable expectations. On February 6, 2007 at the encouragement of a friend I created Second Chance to Live. Second Chance to Live, which is located at http://secondchancetolive.wordpress.com presents topics in such a way to encourage, motivate and empower the reader to live life on life’s terms. I believe our circumstances are not meant to keep us down, but to build us up. As a traumatic brain injury survivor, I speak from my experience, strength and hope. As a professional, I provide information to encourage, motivate and empower both disabled and non-disabled individuals to not give up on their process.

Please encourage your readers to visit Second Chance to Live at http://secondchancetolive.wordpress.com

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Disscoiation between analgesic and addictive effects of pain-killers

Common pain-killers like Morphine have both pair-relieving as well as tolerance and addictive effects. Opiates, it had been theorized earlier, were able to relieve pain via a mechanism that involved the neurotransmitter Serotonin. For the first time , this has been decisively proved to be so, by examining the effects of pain-killer on mice that were engineered to have the serotonin producing gene, Lxmb, silenced in the 5-HT neurons. As such these mice completely lacked serotonin in their brains.

It was found that these mice exhibited more sensitivity to pain and also morphine, or other opiates, were not able to relive the pain in these mice. On the other hand the addictive effects of morphine remained intact.

I am tempted to conjecture further. Is it the case that psychological and physical pain share the same neural substrates? Remember that low levels of serotonin cause depression, in which the sensitivity to psychological pain is elevated. this is similar to the fact that the sensitivity for physical pain is heightened in mice lacking serotonin.I am further tempted to stick my neck out and recommend that the experiment be perormed with mice that have dopamine producing neurons silenced in the brain. If such mice can survive to adulthood, would they exhibit the analgesic effects of morphine, but not its addictive effects? anyway this dissociation between analgesic and addictive effects of morphine would have serious pharmacological effects.

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Good Mood + Intuition = Magical Thinking = Psychosis?

There is a nice little study that shows that good mood induces one to be more superstitious or prone to believe in things like UFO's or the Voodoo dolls.

In the experiment they induced good mood by making people imagine a scenario wherein the participant helped a lost child find his/her parents. The mood was thus experimentally manipulated. subsequently they were showed a documentary about UFOs. Those who were in good mood as compared to neutral mood, were more likely to believe in the UFO's. This was true for only those whose decision making style was intuitive. Those, who were more rationally inclined, were not made to believe in UFO's by the good mood manipulation.

In a follow up study, those who were more happily inclined and intuitive were less successfully at a dart throwing game in which the target was a photo of a baby. This is due to their attributing some similarity to the target with themselves and thus this impedes their performance.


Now, it is well known, that those bipolar patients who are having a high can also have psychosis. Also while depressive phase of bipolar is marked by sad mood (amongst other), the manic phase is characterized by a happy and exuberant mood (although irritability of mood is also present). It thus seems evident that in a manic phase , people who are intuitive may resort to Magical Thinking and this may lead to full blown psychosis as they lose contact with reality. This is an interesting hypothesis and I would like to see some studies on bipolar patients - both those who are rationally inclined and those whose thinking style is intuitive- and investigate is those who have psychotic episodes are more intuitively inclined- as a happy mood is a commonality to all bipolars in the manic phase.

Also, I haven't read the original study - couldn't find on the web- so if someone can point me to a link to the same, or to some other related studies, I would be very thankful.

Hat tip: Mind Hacks

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True Lies: More thoughts on Autism and Schizophrenia

There is a fantastical article by Simon Baron-Cohen about how autistic children are more honest than the rest of us and how the neurotypical human brain is characterized by an ability to deceive.

As we all know, Autistic children have troubles with meta-representation, or believing that there could be two versions of reality- one that is factually correct, and which they themselves may hold; and another that is incorrect, but exists in the mind of another human being. Thus, they may not have any problem with knowing some fact about the world, but are greatly disadvantaged when it comes to knowing facts about other people's mind- as they cannot conceive that somebody can have beliefs that are different from the Reality- in other words that someone has 'false beliefs'.

As per Simon, the capacity to deceive involves the ability to know that one can have false beliefs; and also that one can manipulate the beliefs of another person, so that the person ends up with a false belief. I doubt whether the first ability is necessarily compromised in people with Autism. After all, they themselves may have had false beliefs about the world (say thinking that sun revolves around the earth) and thus may similarly conjecture that others can also have false beliefs. The trouble may lie elsewhere- they may lack the ability to discern that whatever beliefs they have (whether true or false), the other person might not necessarily have the same beliefs. That is they may confuse their own beliefs with that of another and would not have a higher level meta-representation, that someone can have a different belief set. Thus, the trouble is not with having beliefs- but with the ability to say and understand that "I believe that john believes this". They may not comprehend such a sentence or thought- as it is superfluous in their world, where their beliefs are consistent with Reality (or are false) and the other person's beliefs also being consistent with Reality are one and the same. Thus they never require , or are able to use, this recursive ability. I believe this deficit in recursive ability may to some extent explain their language difficulties too. coming back to point, as they themselves cannot comprehend that "I believe john believes X.", so also they are unable to comprehend that 'john believes I believe X". thus, in their innocent and simplistic world, their is no room for either manipulating others via deception; nor of not trusting and always being on their guard against what someone says or does. Thus, they would take sentences at their face value.

I came across this article via The Thinking Blog and there Mary makes some interesting points about whether all deception is bad and all honesty is good; and I concur fully with her that sometimes deception is needed and can be put to good purpose and sometimes truth is not desirable or even moral as per the situation. What is more instrumental is the motive with which the truth or lie is chosen. Thus, I personally am of the opinion that we do need an ability to deceive, but the character to keep the trait in check and to put in good use only.

Simon also makes a point that we treat Autistic traits like honesty as traits on a continuum and not as deficits and I agree with him there too. He treats the normal , social brain as the extreme end of the this trait on which the autistic are the other end; and here I differ. I have already made some strong cases for Schizophrenia to be at the other end; and I would like to support that position by drawing on Simon's analysis.

If we believe that one trait that Autistic lack is deception and meta-representation or ability to read minds, then the Schizophrenics are bound to be too good at it (as per my thinking they are two ends of a creativity spectrum).

• The Schizophrenics may use so much meta-representation (thinking that goes 'I think he thinks that I think that Mary thinks ....') that they may not only get confused, but sound disoriented and disorganized as they may assume too much about what the other person believes. Much of the incoherence in a psychotic speech may be due to too much of shared context - or too much of' he-knows-what-she-knows-that-I-know' sort of thinking. Also keeping multiple perspectives or belief sets may tax their normal working memory capacities, making them sound incoherent.
• Also as opposed to Autistics , who think people do not have an ability to mind-read- as they themselves lack it- the Schizophrenics may be marked by an increased propensity to consider that people can mind read and that too to a very great extent. This may underlie the frequently found delusion in schizophrenia that their thoughts are being broadcasted- that other can read their mind--or at least they want to read their minds using Gizmo's like satellites, headphones etc. The schizophrenic, after all, knows the advantages that can be obtained if one can mind read.
• In its extreme, as the Schizophrenics have too much obsession with mind reading abilities- and the corollary ability to deceive- , they may think that people , in general, are deceptive and manipulators. This may explain why other people would like to insert thoughts or tamper with their thoughts/ memories etc. This may easily give rise to delusions of control.
  
• the ability and propensity to deceive, would also explain the paranoia they feel- after all in their warped world view , all, like them, have immense capacity to deceive/ manipulate- and thus is a potential threat- an untrustable person. This gives rise to the paranoid delusions of schizophrenia.
• Lastly, the obsession of schizophrenics with modeling other minds may lead to multiple personality syndrome (although I know this is not recognized by Psychiatry).

I , like Mary, am not taking sides on whether naive honesty is better or tendency to deceive/camouflage is better; I believe both have their utilities and one should be flexible enough to use both capacities at will. But as we know that much of Human evolution is driven by our capacity to deceive , I would classify schizophrenia as the cost we pay for human Evolution; and Autism as a developmental disorder- We humans are meant to be social and are meant to hide all our raw feelings/ beliefs / thoughts from other persons. Let us deceive, but let us keep that in check- or else be prepared for insanity.

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Answer to the last week's question

Well, the answer is (c) i.e emergence of strong reciprocity is consistent with the observed behavior in the ultimatum game. The evolution of strong reciprocity requires that some people be willing to inflict punishment on the cheaters/free-loafers , even at considerable cost to themselves. This is exactly what people are doing by refusing low offers which they see as an injustices/ unfairness and their behavior of refusing the small offer harms the perpetrator of injustice, even though at cost to themselves.
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