The superiority illusion

Following up on my promise to cover a few papers about self-deception, the second in the series is about the superiority illusion (the first was about depressive realism).

Yamada et al. (2013) sought to uncover the origins of the ubiquitous belief that oneself is “superior to average people along various dimensions, such as intelligence, cognitive ability, and possession of desirable traits” (p. 4363). The sad statistical truth is the MOST people are average; that’s the whole definitions of ‘average’, really… But most people think they are superior to others.

Twenty-four young males underwent resting-state fMRI and PET scanning. The first scanner is of the magnetic resonance type and tracks where you have most of the blood going in the brain at any particular moment. More blood flow to a region is interpreted as that region being active at that moment.

The word ‘functional’ means that the subject is performing a task while in the scanner and the resultant brain image is correspondent to what the brain is doing at that particular moment in time. On the other hand, ‘resting-state’ means that the individual did not do any task in the scanner, s/he just sat nice and still on the warm pads listening to the various clicks, clacks, bangs & beeps the coils make. The subjects were instructed to rest with their eyes open. Good instruction, given than many subjects fall asleep in resting state MRI studies, even in the terrible racket that the coils make that sometimes can reach 125 Db. Let me explain: an MRI is a machine that generates a huge magnetic field (60,000 times stronger than Earth’s!) by shooting rapid pulses of electricity through a coiled wire, called gradient coil. These pulses of electricity or, in other words, the rapid on-off switchings of the electrical current make the gradient coil vibrate very loudly.

A PET scanner functions on a different principle. The subject receives a shot of a radioactive substance (called tracer) and the machine tracks its movement through the subject’s body. In this experiment’s case, the tracer was raclopride, a D2 dopamine receptor antagonist.

The behavioral data, meaning the questionnaires results showed that, curiously, the superiority illusion belief was not correlated with anxiety or self-esteem scores, but, not curiously, it was negatively correlated with helplessness, a measure of depression. Makes sense, especially from the view of depressive realism.

The imaging data suggests that dopamine binding on its striatal D2 receptors attenuate the functional connectivity between the left sensoriomotor striatum (SMST, a.k.a postcommissural putamen) and the dorsal anterior cingulate cortex (daCC). And this state of affairs gives rise to the superiority illusion (see Fig. 1).

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Fig. 1. The superiority illusion arises from the suppression of the dorsal anterior cingulate cortex (daCC) – putamen functional connection by the dopamine coming from the substantia nigra/ ventral tegmental area complex (SN/VTA) and binding to its D2 striatal receptors. Credits: brain diagram; Wikipedia, other brain structures and connections: Neuronicus, data: Yamada et al. (2013, doi: 10.1073/pnas.1221681110). Overall: Public Domain

This was a frustrating paper. I cannot tell if it has methodological issues or is just poorly written. For instance, I have to assume that the dACC they’re talking about is bilateral and not ipsilateral to their SMST, meaning left. As a non-native English speaker myself I guess I should cut the authors a break for consistently misspelling ‘commissure’ or for other grammatical errors for fear of being accused of hypocrisy, but here you have it: it bugged me. Besides, mine is a blog and theirs is a published peer-reviewed paper. (Full Disclosure: I do get editorial help from native English speakers when I publish for real and, except a few personal style quirks, I fully incorporate their suggestions). So a little editorial help would have gotten a long way to make the reading more pleasant. What else? Ah, the results are not clearly explained anywhere, it looks like the authors rely on obviousness, a bad move if you want to be understood by people slightly outside your field. From the first figure it looks like only 22 subjects out of 24 showed superiority illusion but the authors included 24 in the imaging analyses, or so it seems. The subjects were 23.5 +/- 4.4 years, meaning that not all subjects had the frontal regions of the brain fully developed: there are clear anatomical and functional differences between a 19 year old and a 27 year old.

I’m not saying it is a bad paper because I have covered bad papers; I’m saying it was frustrating to read it and it took me a while to figure out some things. Honestly, I shouldn’t even have covered it, but I spent some precious time going through it and its supplementals, what with me not being an imaging dude, so I said the hell with it, I’ll finish it; so here you have it :).

By Neuronicus, 13 December 2017

REFERENCE: Yamada M, Uddin LQ, Takahashi H, Kimura Y, Takahata K, Kousa R, Ikoma Y, Eguchi Y, Takano H, Ito H, Higuchi M, Suhara T (12 Mar 2013). Superiority illusion arises from resting-state brain networks modulated by dopamine. Proceedings of the National Academy of Sciences of the United States of America, 110(11):4363-4367. doi: 10.1073/pnas.1221681110. ARTICLE | FREE FULLTEXT PDF 

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Can you tickle yourself?

As I said before, with so many science outlets out there, it’s hard to find something new and interesting to cover that hasn’t been covered already. Admittedly, sometimes some new paper comes out that is so funny or interesting that I too fall in line with the rest of them and cover it. But, most of the time, I try to bring you something that you won’t find it reported by other science journalists. So, I’m sacrificing the novelty for originality by choosing something from my absolutely huge article folder (about 20 000 papers).

And here is the gem for today, titled enticingly “Why can’t you tickle yourself?”. Blakemore, Wolpert & Frith (2000) review several papers on the subject, including some of their own, and arrive to the conclusion that the reason you can’t tickle yourself is because you expect it. Let me explain: when you do a movement that results in a sensation, you have a pretty accurate expectation of how that’s going to feel. This expectation then dampens the sensation, a process probably evolved to let you focus on more relevant things in the environment that on what you’re doing o yourself (don’t let your mind go all dirty now, ok?).

Mechanistically speaking, it goes like this: when you move your arm to tickle your foot, a copy of the motor command you gave to the arm (the authors call this “efference copy”) goes to a ‘predictor’ region of the brain (the authors believe this is the cerebellum) that generates an expectation (See Fig. 1). Once the movement has been completed, the actual sensation is compared to the expected one. If there is a discrepancy, you get tickled, if not, not so much. But, you might say, even when someone else is going to tickle me I have a pretty good idea what to expect, so where’s the discrepancy? Why do I still get tickled when I expect it? Because you can’t fool your brain that easily. The brain then says; “Alright, alright, we expect tickling. But do tell me this, where is that motor command? Hm? I didn’t get any!” So here is your discrepancy: when someone tickles you, there is the sensation, but no motor command, signals 1 and 2 from the diagram are missing.

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Fig. 1. My take on the tickling mechanism after Blakemore, Wolpert & Frith (2000). Credits. Picture: Sobotta 1909, Diagram: Neuronicus 2016. Data: Blakemore, Wolpert & Frith (2002). Overall: Public Domain

Likewise, when someone tickles you with your own hand, there is an attenuation of sensation, but is not completely disappeared, because there is some registration in the brain regarding the movement of your own arm, even if it was not a motor command initiated by you. So you get tickled just a little bit. The brain is no fool: is aware of who had done what and with whose hands (your dirty mind thought that, I didn’t say it!) .

This mechanism of comparing sensation with movement of self and others appears to be impaired in schizophrenia. So when these patients say that “I hear some voices and I can’t shut them up” or ” My hand moved of its own accord, I had no control over it”, it may be that they are not aware of initiating those movements, the self-monitoring mechanism is all wacky. Supporting this hypothesis, the authors conducted an fMRI experiment (Reference 2) where they showed that that the somatosensory and the anterior cingulate cortices show reduced activation when attempting to self-tickle as opposed to being tickled by the experimenter (please, stop that line of thinking…). Correspondingly, the behavioral portion of the experiment showed that the schizophrenics can tickle themselves. Go figure!

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Reference 1: Blakemore SJ, Wolpert D, & Frith C (3 Aug 2000). Why can’t you tickle yourself? Neuroreport, 11(11):R11-6. PMID: 10943682. ARTICLE FULLTEXT

Reference 2: Blakemore SJ, Smith J, Steel R, Johnstone CE, & Frith CD (Sep 2000, Epub 17 October 2000). The perception of self-produced sensory stimuli in patients with auditory hallucinations and passivity experiences: evidence for a breakdown in self-monitoring. Psychological Medicine, 30(5):1131-1139. PMID: 12027049. ARTICLE

By Neuronicus, 7 August 2016

Not all children diagnosed with ADHD have attention deficits

ADHD

Given the alarming increase in the diagnosis of attention deficit/hyperactivity disorder (ADHD) over the last 20 years, I thought pertinent to feature today an older paper, from the year 2000.

Dopamine, one of the chemicals that the neurons use to communicate, has been heavily implicated in ADHD. So heavily in fact that Ritalin, the main drug used for the treatment of ADHD, has its main effects by boosting the amount of dopamine in the brain.

Swanson et al. (2000) reasoned that people with a particular genetic abnormality that makes their dopamine receptors work less optimally may have more chances to have ADHD. The specialist reader may want to know that the genetic abnormality in question refers to a 7-repeat allele of a 48-bp variable number of tandem repeats in exon 3 of the dopamine receptor number 4 located on chromosome 11, whose expression results in a weaker dopamine receptor. We’ll call it DRD4,7-present as opposed to DRD4,7-absent (i.e. people without this genetic abnormality).

They had access to 96 children diagnosed with ADHD after the diagnostic criteria of DSM-IV and 48 matched controls (children of the same gender, age, school affiliation, socio-economic status etc. but without ADHD). About half of the children diagnosed with ADHD had the DRD4,7-present.

The authors tested the children on 3 tasks:

(i) a color-word task to probe the executive function network linked to anterior cingulate brain regions and to conflict resolution;
(ii) a cued-detection task to probe the orienting and alerting networks linked to posterior parietal and frontal brain regions and to shifting and maintenance of attention; and
(iii) a go-change task to probe the alerting network (and the ability to initiate a series of rapid response in a choice reaction time task), as well as the executive network (and the ability to inhibit a response and re-engage to make another response) (p. 4756).

Invalidating the authors’ hypothesis, the results showed that the controls and the DRD4,7-present had similar performance at these tasks, in contrast to the DRD4,7-absent who showed “clear abnormalities in performance on these neuropsychological tests of attention” (p. 4757).

This means two things:
1) Half of the children diagnosed with ADHD did not have an attention deficit.
2) These same children had the DRD4,7-present genetic abnormality, which has been previously linked with novelty seeking and risky behaviors. So it may be just possible that these children do not suffer from ADHD, but “may be easily bored in the absence of highly stimulating conditions, may show delay aversion and choose to avoid waiting, may have a style difference that is adaptive in some situations, and may benefit from high activity levels during childhood” (p. 4758).

Great paper and highly influential. The last author of the article (meaning the chief of the laboratory) is none other that Michael I. Posner, whose attentional networks, models, and tests feature every psychology and neuroscience textbook. If he doesn’t know about attention, then I don’t know who is.

One of the reasons I chose this paper is because it seems to me that a lot of teachers, nurses, social workers, or even pediatricians feel qualified to scare the living life out of parents by suggesting that their unruly child may have ADHD. In deference to most form the above-mentioned professions, the majority of people recognize their limits and tell the concerned parents to have the child tested by a qualified psychologist. And, unfortunately, even that may result in dosing your child with Ritalin needlessly when the child’s propensity toward a sensation-seeking temperament and extravert personality, may instead require a different approach to learning with a higher level of stimulation (after all, the children form the above study had been diagnosed by qualified people using their latest diagnosis manual).

Bottom line: beware of any psychologist or psychiatrist who does not employ a battery of attention tests when diagnosing your child with ADHD.

Reference: Swanson J, Oosterlaan J, Murias M, Schuck S, Flodman P, Spence MA, Wasdell M, Ding Y, Chi HC, Smith M, Mann M, Carlson C, Kennedy JL, Sergeant JA, Leung P, Zhang YP, Sadeh A, Chen C, Whalen CK, Babb KA, Moyzis R, & Posner MI. (25 April 2000). Attention deficit/hyperactivity disorder children with a 7-repeat allele of the dopamine receptor D4 gene have extreme behavior but normal performance on critical neuropsychological tests of attention. Proceedings of the National Academy of Sciences of the United States of America, 97(9):4754-4759. doi: 10.1073/pnas.080070897. Article | FREE PDF

P.S. If you think that “weeell, this research happened 16 years ago, surely something came out of it” then think again. The newer DSM-V’s criteria for diagnosis are likely to cause an increase in the prevalence of diagnosis of ADHD.

By Neuronicus, 26 February 2016

The runner’s euphoria and opioids

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The runner’s high is most likely due to release of the endorphins binding to the opioid receptors according to Boecker et al. (2008, doi: 10.1093/cercor/bhn013). Image courtesy of Pixabay.

We all know that exercise is good for you: it keeps you fit, it reduces stress and improves your mood. And also, sometimes, particularly after endurance running, it gets you high. The mechanism of euphoria reported by some runners after resistance training is unknown. Here is a nice paper trying to figure it out.

Boecker et al. (2008) scanned 10 trained male athletes at rest and after 2 hour worth of endurance running. By “trained athletes” they mean people that ran for 4-10 hours weekly for the past 2 years. The scanning was done using a positron emission tomograph (PET). The PET looks for a particular chemical that has been injected into the bloodstream of the subjects, in this case non-selective opioidergic ligand (it binds to all opioid receptors in the brain; morphine, for example, binds only to a subclass of the opioid receptors).

The rationale is as follows: if we see an increase in ligand binding, then the receptors were free, unoccupied, showing a reduction in the endogenous neurotransmitter, that is the substance that the brain produces for those receptors; if we see a decrease in the ligand binding it was because the receptors were occupied, meaning that there was an increase in the production of the endogenous neurotransmitter. The endogenous neurotransmitters for the opioid receptors are the endorphins (don’t confuse them with epinephrine a.k.a. adrenaline; different systems entirely).

After running, the subjects reported that they are euphoric and happy, but no change in other feelings (confusion, anger, sadness, fear etc.; there was a reduction in fear, but it was not significant). The scanning showed that it was less binding of the opioidergic ligand in many places in the brain (for the specialist, here you go: prefrontal/orbitofrontal cortices, dorsolateral prefrontal cortex, anterior and posterior cingulate cortex, insula and parahippocampal gyrus, sensorimotor/parietal regions, cerebellum and basal ganglia).

Regression analysis showed that there was a link between the euphoria feeling and the receptor occupancy: the more euphoric the people said they were, the more endorphines (i.e. endogenous opioids) they had bound in the brain. This study is the first to show this kind of link.

Reference: Boecker H, Sprenger T, Spilker ME, Henriksen G, Koppenhoefer M, Wagner KJ, Valet M, Berthele A, & Tolle TR. (Nov 2008, Epub 21 Feb 2008). The Runner’s High: Opioidergic Mechanisms in the Human Brain. Cerebral Cortex, 18:2523–2531. doi:10.1093/cercor/bhn013. Article | FREE FULLTEXT PDF

By Neuronicus, 28 November 2015

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How grateful would you feel after watching a Holocaust documentary? (Before you comment, READ the post first)

form Fox et al. (2015)
form Fox et al. (2015)

How would you feel if one of your favourite scientists published a paper that is, to put it in mild terms, not to their very best? Disappointed? Or perhaps secretly gleeful that even “the big ones” are not always producing pearl after pearl?

This is what happened to me after reading the latest paper of the Damasio group. Fox et al. (2015) decided to look for the neural correlates of gratitude. That is, stick people in fMRI, make them feel grateful, and see what lights up. All well and good, except they decided to go with a second-hand approach, meaning that instead of making people feel grateful (I don’t know how, maybe giving them something?), they made the participants watch stories in which gratitude may have been felt by other people (still not too too bad, maybe watching somebody helping the elderly). But, the researchers made an in-house documentary about the Holocaust and then had several actual Holocaust survivors tell their story (taken from the SC Shoah Foundation Institutes Visual History Archive), focusing on the part where their lives were saved or they were helped by others by giving them survival necessities. Then, the subjects were asked to immerse themselves in the story and tell how grateful they felt if they were the gift recipients.

I don’t know about you, but I don’t think that after watching a documentary about the Holocaust (done with powerfully evocative images and professional actor voice-overs, mind you!) and seeing people tell the horrors they’ve been through and then receiving from a Good Samaritan some food or shelter, gratitude would not have been my first feeling. Anger perhaps? That such abominable thing as the Holocaust was perpetrated by my fellow humans? Sorrow? Sadness? Sick to my stomach? Compassion for the survivors? Maybe I am blatantly off-Gauss here, but I don’t think Damasio et co. measured what they thought they were measuring.

Anyway, for what is worth, the task produced significant activity in the medial prefrontal cortex (which is involved in so many behaviors that is not even worth listing them), along with the usual suspects in a task as ambiguous as this, like various portions of the anterior cingulate and orbitofrontal cortices.

Reference: Fox GR, Kaplan J, Damasio H, & Damasio A (30 September 2015). Neural correlates of gratitude. Frontiers in Psycholology, 6:1491. doi: 10.3389/fpsyg.2015.01491. Article | FREE FULLTEXT PDF

By Neuronicus, 27 October 2015

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