Vanity and passion fruit

Ultraviolet irradiation exposure from our sun accelerates the skin aging, process called photoaging. It can even cause skin cancers. There has been some considerable research on how our beloved sun does that.

For example, one way the UV radiation leads to skin damage is by promoting the production of free radicals as reactive oxygen species (ROS), which do many bad things, like direct DNA damage. Another bad thing done by ROS is the upregulation of the mitogen-activated protein kinase (MAPK) signaling pathway which activates all sorts of transcription factors which, in turn, produce proteins that lead to collagen degradation and voilà, aged skin. I know I lost some of you at the MAPK point; you can think of MAPK as a massive proteinaceous hub, a multi-button console with many inputs and outputs. A very sensitive and incredibly complex hub that controls nearly all important aspects of cell function, with many feedback loops, so if you mess with it, cell Armageddon may be happening. Or nothing at all. It’s that complex.

But I digress. What MAPK is doing is less relevant for the paper I am introducing to you today than the fact that we have physiological markers for skin aging due to UV. Bravo et al. (2017) cultured human skin cells in a Petri dish, treated them with various concentrations of an extract of passion fruit (Passiflora tarminiana) and then bombarded them with UV (the B type, 280–315 nm). The authors made the extract themselves, is not something you just buy (yet).

The UV produced the expected damage, translated as increased matrix mettoproteinase-1 (MMP-1), collagenase, and ROS production and decreased procollagen. Pretreatment with passion fruit extract significantly mitigated these UV effects in a dose-dependant manner. The concentration of their concoction that worked best was 10 μg/mL. Then the authors did some more chemistry to figure out what in their concoction is responsible, or at least probably responsible, for the observed wonderful effects. The authors believe the procyianidins and flavonoids are the culprits because 1) they have been proven to be strong antioxidants before and 2) this plant has them in very high amounts.

Good news then for the antiaging cosmetics industry. Perhaps even for dermatologists and their patients.

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Reference: Bravo K, Duque L, Ferreres F, Moreno DA, & Osorio E. (EPUB ahead of print: 3 Feb 2017). Passiflora tarminiana fruits reduce UVB-induced photoaging in human skin fibroblasts. Journal of Photochemistry and Photobiology, 168: 78-88. PMID: 28189068, DOI: 10.1016/j.jphotobiol.2017.01.023. ARTICLE

By Neuronicus, 13 February 2017

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Aging and its 11 hippocampal genes

Aging is being quite extensively studied these days and here is another advance in the field. Pardo et al. (2017) looked at what happens in the hippocampus of 2-months old (young) and 28-months old (old) female rats. Hippocampus is a seahorse shaped structure no more than 7 cm in length and 4 g in weight situated at the level of your temples, deep in the brain, and absolutely necessary for memory.

First the researchers tested the rats in a classical maze test (Barnes maze) designed to assess their spatial memory performance. Not surprisingly, the old performed worse than the young.

Then, they dissected the hippocampi and looked at neurogenesis and they saw that the young rats had more newborn neurons than the old. Also, the old rats had more reactive microglia, a sign of inflammation. Microglia are small cells in the brain that are not neurons but serve very important functions.

After that, the researchers looked at the hippocampal transcriptome, meaning they looked at what proteins are being expressed there (I know, transcription is not translation, but the general assumption of transcriptome studies is that the amount of protein X corresponds to the amount of the RNA X). They found 210 genes that were differentially expressed in the old, 81 were upregulated and 129 were downregulated. Most of these genes are to be found in human too, 170 to be exact.

But after looking at male versus female data, at human and mouse aging data, the authors came up with 11 genes that are de-regulated (7 up- and 4 down-) in the aging hippocampus, regardless of species or gender. These genes are involved in the immune response to inflammation. More detailed, immune system activates microglia, which stays activated and this “prolonged microglial activation leads to the release of pro-inflammatory cytokines that exacerbate neuroinflammation, contributing to neuronal loss and impairment of cognitive function” (p. 17). Moreover, these 11 genes have been associated with neurodegenerative diseases and brain cancers.

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These are the 11 genes: C3 (up), Cd74  (up), Cd4 (up), Gpr183 (up), Clec7a (up), Gpr34 (down), Gapt (down), Itgam (down), Itgb2 (up), Tyrobp (up), Pld4 (down).”Up” and “down” indicate the direction of deregulation: upregulation or downregulation.

I wish the above sentence was as explicitly stated in the paper as I wrote it so I don’t have to comb through their supplemental Excel files to figure it out. Other than that, good paper, good work. Gets us closer to unraveling and maybe undoing some of the burdens of aging, because, as the actress Bette Davis said, “growing old isn’t for the sissies”.

Reference: Pardo J, Abba MC, Lacunza E, Francelle L, Morel GR, Outeiro TF, Goya RG. (13 Jan 2017, Epub ahead of print). Identification of a conserved gene signature associated with an exacerbated inflammatory environment in the hippocampus of aging rats. Hippocampus, doi: 10.1002/hipo.22703. ARTICLE

By Neuronicus, 25 January 2017

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100% Effective Vaccine

A few days ago I was reading random stuff on the internet, as is one’s procrastination proclivity, catching up after the holiday, and I exclaimed out loud: “They discovered an 100% effective Ebola Vaccine!”. I expected some ‘yeay’-s or at least some grunts along the lines of ‘that’s nice’ or ‘cool’. Naturally, I turned around from my computer to check the source of unaccustomed silence to the announcement of such good news or, at least, to make sure that everybody is still breathing and present in the room. What met my worried glare was a gloom face and a shaking head. That’s because news like that are misleading, because, duh, it finally dawned on me, there is no such thing as ‘100% effective vaccine’.

And yet…, and yet this is exactly what Henao-Restrepo et al. (2016) say they found! The study is huge, employing more that 10 000 people. Such a tremendous endeavor has been financed by WHO (World Health Organization) and various departments from several countries (UK, USA, Switzerland, South Africa, Belgium, Germany, France, Guinea, and Norway) and, I’m assuming, a lot of paid and unpaid volunteers. I cannot even imagine the amount of work and the number of people that made this happen. And the coordination required for such speedy results!

The successful vaccine in rodents and non-human primates, called the recombinant, replication-competent, vesicular stomatitis virus-based vaccine expressing the glycoprotein of a Zaire Ebolavirus (rVSV-ZEBOV) has been taken to the Republic of Guinea and rapidly administered to volunteers who were in contact with somebody that had Ebola symptoms. And their contacts. I mean the contacts and the contacts of contacts of the Ebola patient. Who were contacted by the researchers within 2 days of a new Ebola case based on the patient’s list of contacts. And of contacts of contacts. Is not that complicated, honest.

After vaccinations, the “vaccinees were observed for 30 min post-vaccination and at home visits on days 3, 14, 21, 42, 63, and 84” (p.4). Some volunteers received the vaccine immediately, others after 3 weeks. No one who received the vaccine immediately developed Ebola, which lead the researchers to claim that the vaccine is 100% effective. Only 9 from the delayed vaccination group developed Ebola within 10 days of vaccination, but the researchers figured that these people probably contacted Ebola prior to the vaccination, since the disease requires typically about 10 days to show its ugly  horns.

So this is great news. Absolutely great. Even if, as always, I could nitpick thorough the paper, squabble over the “typically” 10-day incubation period, and cock an eyebrow at the new-fangled ring vaccination design as opposed to the old-fashioned placebo approach. Even after these minor criticisms this is – I repeat – GREAT NEWS!

P.S. Don’t ever say that the UN didn’t do anything for you.

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Reference: Henao-Restrepo AM, Camacho A, Longini IM, Watson CH, Edmunds WJ, Egger M, Carroll MW, Dean NE, Diatta I, Doumbia M, Draguez B, Duraffour S, Enwere G, Grais R, Gunther S, Gsell PS, Hossmann S, Watle SV, Kondé MK, Kéïta S, Kone S, Kuisma E, Levine MM, Mandal S, Mauget T, Norheim G, Riveros X, Soumah A, Trelle S, Vicari AS, Røttingen JA, Kieny MP. (22 Dec 2016). Efficacy and effectiveness of an rVSV-vectored vaccine in preventing Ebola virus disease: final results from the Guinea ring vaccination, open-label, cluster-randomised trial (Ebola Ça Suffit!). Lancet. pii: S0140-6736(16)32621-6. doi: 10.1016/S0140-6736(16)32621-6. PMID: 28017403 [Epub ahead of print] ARTICLE | FREE FULLTEXT PDF | Good Nitpicking in The Conversation

By Neuronicus, 18 January 2017

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Don’t eat snow

Whoever didn’t roll out a tongue to catch a few snowflakes? Probably only those who never encountered snow.

The bad news is that snow, particularly urban snow is bad, really bad for you. The good news is that this was not always the case. So there is hope that in the far future it will be pristine again.

Nazarenko et al. (2016) constructed a very clever contraption that reminds me of NASA space exploration instruments. The authors refer to this by the humble name of ‘environmental chamber’, but is in fact a complex construction with different modules designed to measure out how car exhaust and snow interact (see Fig. 1).

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Fig. 1 from Nazarenko et al. (2016, DOI: 10.1039/c5em00616c). Released under CC BY-NC 3.0.

After many experiments, researchers concluded that snow absorbs pollutants very effectively. Among the many kinds of organic compounds soaked by snow in just one hour after exposure to fume exhaust, there were the infamous BTEX (benzene, toluene, ethylbenzene, and xylenes). The amounts of these chemicals in the snow were not at all negligible; to give you an example, the BTEX concentration increased from virtually 0 to 50 and up to 380 ug kg-1. The authors provide detailed measurements for all the 40+ compounds they have identified.

Needles to say, many these compounds are known carcinogenics. Snow absorbs them, alters their size distributions, and then it melts… Some of them may be released back in the air as they are volatile, some will go in the ground and rivers as polluted water. After this gloomy reality check, I’ll leave you with the words of the researchers:

“The accumulation and transfer of pollutants from exhaust – to snow – to meltwater need to be considered by regulators and policy makers as an important area of focus for mitigation with the aim to protect public health and the environment” (p. 197).

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Reference: Nazarenko Y, Kurien U, Nepotchatykh O, Rangel-Alvarado RB, & Ariya PA. (Feb 2016). Role of snow and cold environment in the fate and effects of nanoparticles and select organic pollutants from gasoline engine exhaust. Environmental Science: Processes & Impacts, 18(2):190-199. doi: 10.1039/c5em00616c. ARTICLE | FREE FULTEXT PDF 

By Neuronicus, 26 December 2016

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Soccer and brain jiggling

There is no news or surprise that strong hits to the head produce transient or permanent brain damage. But how about mild hits produced by light objects like, say, a volley ball or soccer ball?

During a game of soccer, a player is allowed to touch the ball with any part of his/her body minus the hands. Therefore, hitting the ball with the head, a.k.a. soccer heading, is a legal move and goals marked through such a move are thought to be most spectacular by the refined connoisseur.

A year back, in 2015, the United States Soccer Federation forbade the heading of the ball by children 10 years old and younger after a class-action lawsuit against them. There has been some data that soccer players display loss of brain matter that is associated with cognitive impairment, but such studies were correlational in nature.

Now, Di Virgilio et al. (2016) conducted a study designed to explore the consequences of soccer heading in more detail. They recruited 19 young amateur soccer players, mostly male, who were instructed to perform 20 rotational headings as if responding to corner kicks in a game. The ball was delivered by a machine at a speed of approximately 38 kph. The mean force of impact for the group was 13.1 ± 1.9 g. Immediately after the heading session and at 24 h, 48 h and 2 weeks post-heading, the authors performed a series of tests, among which are a transcranial magnetic stimulation (TMS) recording, a cognitive function assessment (by using the Cambridge Neuropsychological Test Automated Battery), and a postural control test.

Not being a TMS expert myself, I was wondering how do you record with a stimulator? TMS stimulates, it doesn’t measure anything. Or so I thought. The authors delivered brief  (1 ms) stimulating impulses to the brain area that controls the leg (primary motor cortex). Then they placed an electrode over the said muscle (rectus femoris or quadriceps femoris) and recorded how the muscle responded. Pretty neat. Moreover, the authors believe that they can make inferences about levels of inhibitory chemicals in the brain from the way the muscle responds. Namely, if the muscle is sluggish in responding to stimulation, then the brain released an inhibitory chemical, like GABA (gamma-amino butyric acid), hence calling this process corticomotor inhibition. Personally, I find this GABA inference a bit of a leap of faith, but, like I said, I am not fully versed in TMS studies so it may be well documented. Whether or not GABA is responsible for the muscle sluggishness, one thing is well documented though: this sluggishness is the most consistent finding in concussions.

The subjects had impaired short term and long term memory functions immediately after the ball heading, but not 24 h or more later. Also transient was the corticomotor inhibition. In other words, soccer ball heading results in measurable changes in brain function. Changes for the worst.

Even if these changes are transient, there is no knowing (as of yet) what prolonged ball heading might do. There is ample evidence that successive concussions have devastating effects on the brain. Granted, soccer heading does not produce concussions, at least in this paper’s setting, but I cannot think that even sub-concussion intensity brain disruption can be good for you.

On a lighter note, although the title of the paper features the word “soccer”, the rest o the paper refers to the game as “football”. I’ll let you guess the authors’ nationality or at least the continent of provenance ;).

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Reference: Di Virgilio TG, Hunter A, Wilson L, Stewart W, Goodall S, Howatson G, Donaldson DI, & Ietswaart M. (Nov 2016, Epub 23 Oct 2016). Evidence for Acute Electrophysiological and Cognitive Changes Following Routine Soccer Heading. EBioMedicine, 13:66-71. PMID: 27789273, DOI: 10.1016/j.ebiom.2016.10.029. ARTICLE | FREE FULLTEXT PDF

By Neuronicus, 20 December 2016

Scientists don’t know the risks & benefits of science

If you want to find out how bleach works or what keeps the airplanes in the air or why is the rainbow the same sequence of colors or if it’s dangerous to let your kid play with snails would you ask a scientist or your local priest?

The answer is very straightforward for most of the people. Just that for a portion of the people the straightforwardness is viewed by the other portion as corkscrewedness. Or rather just plain dumb.

Cacciatore et al. (2016) asked about 5 years ago 2806 American adults how much they trust the information provided by religious organizations, university scientists, industry scientists, and science/technology museums. They also asked them about their age, gender, race, socioeconomic status, income as well as about Facebook use, religiosity, ideology, and attention to science-y content.

Almost 40% of the sample described themselves as Evangelical Christians, one of the largest religious group in USA. These people said they trust more their religious organizations then scientists (regardless of who employs these scientists) to tell the truth about the risks and benefits of technologies and their applications.

The data yielded more information, like the fact that younger, richer, liberal, and white people tended to trust scientists more then their counterparts. Finally, Republicans were more likely to report a religious affiliation than Democrats.

I would have thought that everybody would prefer to take advice about science from a scientist. Wow, what am I saying, I just realized what I typed… Of course people are taking health advice from homeopaths all the time, from politicians rather than environment scientists, from alternative medicine quacks than from doctors, from no-college educated than geneticists. From this perspective then, the results of this study are not surprising, just very very sad… I just didn’t think that the gullible people can also be grouped by political affiliations. I though the affliction is attacking both sides of an ideological isle in a democratic manner.

Of course, this is a survey study, therefore a lot more work is needed to properly generalize these results, from expanding the survey sections (beyond the meager 1 or 2 questions per section) to validation and replication. Possibly, even addressing different aspects of science because, for instance, climate change is a much more touchy subject than, say, apoptosis. And replace or get rid of the “Scientists know best what is good for the public” item; seriously, I don’t know any scientist, including me, who would answer yes to that question. Nevertheless, the trend is, like I said, sad.

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Reference:  Cacciatore MA, Browning N, Scheufele DA, Brossard D, Xenos MA, & Corley EA. (Epub ahead of print 25 Jul 2016). Opposing ends of the spectrum: Exploring trust in scientific and religious authorities. Public Understanding of Science. PMID: 27458117, DOI: 10.1177/0963662516661090. ARTICLE | NPR cover

By Neuronicus, 7 December 2016

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The oldest known anatomically modern humans in Europe

A couple of days ago, on December 1st, was the National Day of Romania, a small country in the South-East of Europe. In its honor, I dug out a paper that shows that some of the earliest known modern humans in Europe were also… dug out there.

Trinkaus et al. (2003) investigated the mandible of an individual found in 2002 by a Romanian speological expedition in Peștera cu Oase (the Cave with Bones), one of the caves in the SouthWest of the country, not far from where Danube meets the Carpathians.

First the authors did a lot of very fine measurement of various aspects of the jaw, including the five teeth, and then compared them with those found in other early humans and Neanderthals. The morphological features place the Oase 1 individual as an early modern human with some Neanderthal features. The accelerator mass spectrometry radiocarbon (14C) direct dating makes him the oldest early modern human discovered to that date in Europe; he’s 34,000–36,000 year old. I’m assuming is a he for no particular reason; the paper doesn’t specify anywhere whether they know the jaw owner’s gender and age. A later paper (Fu et al., 2015) says Oase 1 is even older: 37,000–42,000-year-old.

After this paper it seemed to be a race to see what country can boast to have the oldest human remains on its territory. Italy and UK successfully reassessed their own previous findings thusly: UK has a human maxilla that was incorrectly dated in 1989 but new dating makes it 44,200–39,000 year old, carefully titling their paper “The earliest evidence for anatomically modern humans in northwestern Europe” (Higham et al., 2011) while Italy’s remains that they thought for decades to be Neanderthal turned out to be 45,000-43,000 years old humans, making “the Cavallo human remains […] the oldest known European anatomically modern humans” (Benmazzi et al., 2011).

I wonder what prompted the sudden rush in reassessing the old untouched-for-decades fossils… Probably good old fashioned national pride. Fair enough. Surely it cannot have anything to do with the disdain publicly expressed by some Western Europe towards Eastern Europe, can it? Surely scientists are more open minded than some petty xenophobes, right?

Well, the above thought wouldn’t have even crossed my mind, nor would I have noticed that the Romanians’ discovery has been published in PNAS and the others in Nature, had it not been for the Fu et al. (2015) paper, also published in Nature. This paper does a genetic analysis of the Oase 1 individual and through some statistical inferences that I will not pretend to fully understand they arrive to two conclusions. First, Oase 1 had a “Neanderthal ancestor as recently as four to six generations back”. OK. Proof of interbreeding, nothing new here. But the second conclusion I will quote in full: “However, the Oase individual does not share more alleles with later Europeans than with East Asians, suggesting that the Oase population did not contribute substantially to later humans in Europe.”

Now you don’t need to know much about statistics or about basic logic either to know that from 1 (one) instance alone you cannot generalize to a whole population. That particular individual from the Oase population hasn’t contributed to later humans in Europe, NOT the entire population. Of course it is possible that that is the case, but you cannot scientifically draw that conclusion from one instance alone! This is in the abstract, so everybody can see this, but I got access to the whole paper, which I have read in the hopes against hope that maybe I’m missing something. Nope. The authors did not investigate any additional DNA and they reiterate that the Oase population did not contribute to modern-day Europeans. So it’s not a type-O. From the many questions that are crowding to get out like ‘How did it get past reviewers?’, ‘Why was it published in Nature (interesting paper, but not that interesting, we knew about interbreeding so what makes it so new and exciting)?’, the one that begs to be asked the most is: ‘Why would they say this, when stating the same thing about the Oase 1 individual instead about the Oase population wouldn’t have diminished their paper in any way?’ .

I must admit that I am getting a little paranoid in my older age. But with all the hate that seems to come out and about these days EVERYWHERE towards everything that is “not like me” and “I don’t want it to be like me”, one cannot but wonder… Who knows, maybe it is really just as simple as an overlooked mistake or some harmless national pride so all is good and life goes on, especially since the authors of all four papers discussed above are from various countries and institutions all across the Globe. Should that be the case, I offer my general apologies for suspecting darker motives behind these papers, but I’m not holding my breath.

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References:

1) Trinkaus E, Moldovan O, Milota S, Bîlgăr A, Sarcina L, Athreya S, Bailey SE, Rodrigo R, Mircea G, Higham T, Ramsey CB, & van der Plicht J. (30 Sep 2003, Epub 22 Sep 2003). An early modern human from the Peştera cu Oase, Romania. Proceedings of the National Academy of Sciences U S A,  100(20):11231-11236. PMID: 14504393, PMCID: PMC208740, DOI: 10.1073/pnas.2035108100. ARTICLE  | FREE FULLTEXT PDF

 2) Higham T, Compton T, Stringer C, Jacobi R, Shapiro B, Trinkaus E, Chandler B, Gröning F, Collins C, Hillson S, O’Higgins P, FitzGerald C, & Fagan M. (2 Nov 2011). The earliest evidence for anatomically modern humans in northwestern Europe. Nature. 479(7374):521-4. PMID: 22048314, DOI: 10.1038/nature10484. ARTICLE | FULLTEXT PDF via ResearchGate

3) Benazzi S, Douka K, Fornai C, Bauer CC, Kullmer O, Svoboda J, Pap I, Mallegni F, Bayle P, Coquerelle M, Condemi S, Ronchitelli A, Harvati K, & Weber GW. (2 Nov 2011). Early dispersal of modern humans in Europe and implications for Neanderthal behaviour. Nature, 479(7374):525-8. PMID: 22048311, DOI: 10.1038/nature10617. ARTICLE | FULLTEXT PDF via ResearchGate

4) Fu Q, Hajdinjak M, Moldovan OT, Constantin S, Mallick S, Skoglund P, Patterson N, Rohland N, Lazaridis I, Nickel B, Viola B, Prüfer K, Meyer M, Kelso J, Reich D, & Pääbo S. (13 Aug 2015, Epub 22 Jun 2015). An early modern human from Romania with a recent Neanderthal ancestor. Nature. 524(7564):216-9. PMID: 26098372, PMCID: PMC4537386, DOI:10.1038/nature14558. ARTICLE | FREE FULLTEXT PDF

By Neuronicus, 3 December 2016

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Earliest memories

I found a rather old-ish paper which attempts to settle a curiosity regarding human memory: how far back can we remember?

MacDonald et al. (2000) got 96 participants to fill a 15-minute questionnaire about their demographics and their earliest memories. The New Zealand subjects were in their early twenties, a third of Maori descent, a third of European descent and the last third of Asian descent.

The Maori had the earliest memories, some of them as early as before they turned 1 year old, though the mean was 2 years and 8 months. Next came the Europeans with the mean of 3 years and a half, followed by the Asians with the mean of 4 and 9 months. Overall, most memories seem to occur between 3 and 4 years. There was no difference in gender except for the Asian group where the females reported much later memories, around 6 years.

The subjects were also required to indicate the source of the memory as being personal recollection, family story or photographs. About 86% reported it as personal recollection. The authors argue that even without the remaining 14% the results looks the same. I personally would have left those 14% out if they really don’t make a difference, it would have made the results much neater.

There are a few caveats that one must keep in mind with this kind of studies, the questionnaire studies. One of them is the inherent veracity problem: you rely on human honesty because there is no way to check the data for truth. The fact that the memory may be true or false would not matter for this study, but whether is a personal recollection or a family story would matter. So take the results at face value. Besides, human memory is extremely easy to manipulate, therefore some participants may actually believe that they ‘remember’ an event when in fact it was learned much later from relatives. I also have very early memories and while one of them I believe was told ad nauseam by family members at every family gathering so many times that I incorporated it as actual recollection, there are a couple that I couldn’t tell you for the life of me whether I remember them truly or they too have been subjected to family re-reminiscing.

Another issue might be the very small sample sizes with sub-groups. The authors divided their participants in many subgroups (whether they spoke English first, whether they were raised mainly by the mother etc.) that some subgroups ended up having 2 or 3 members, which is not enough to make a statistical judgement. Which also leads me to multiple comparisons adjustments, which should be more visible.

So not exactly the best paper ever written. Nevertheless, it’s an interesting paper in that even if it doesn’t really establish (in my opinion) when do most people have their earliest true memories, it does point to cultural differences in individuals’ earliest recollections. The authors speculate that that may be due to the emphasis put on detailed stories about personal experiences told by the mother in the early years in some cultures (here Maori) versus a lack of these stories in other cultures (here Asian).

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Reference: MacDonald S, Uesiliana K, & Hayne H. (Nov 2000). Cross-cultural and gender differences in childhood amnesia. Memory. 2000 Nov;8(6):365-76. PMID: 11145068, DOI: 10.1080/09658210050156822. ARTICLE | FULLTEXT PDF

By Neuronicus, 28 November 2016

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Amusia and stroke

Although a complete musical anti-talent myself, that doesn’t prohibit me from fully enjoying the works of the masters in the art. When my family is out of earshot, I even bellow – because it cannot be called music – from the top of my lungs alongside the most famous tenors ever recorded. A couple of days ago I loaded one of my most eclectic playlists. While remembering my younger days as an Iron Maiden concert goer (I never said I listen only to classical music :D) and screaming the “Fear of the Dark” chorus, I wondered what’s new on the front of music processing in the brain.

And I found an interesting recent paper about amusia. Amusia is, as those of you with ancient Greek proclivities might have surmised, a deficit in the perception of music, mainly the pitch but sometimes rhythm and other aspects of music. A small percentage of the population is born with it, but a whooping 35 to 69% of stroke survivors exhibit the disorder.

So Sihvonen et al. (2016) decided to take a closer look at this phenomenon with the help of 77 stroke patients. These patients had an MRI scan within the first 3 weeks following stroke and another one 6 months poststroke. They also completed a behavioral test for amusia within the first 3 weeks following stroke and again 3 months later. For reasons undisclosed, and thus raising my eyebrows, the behavioral assessment was not performed at 6 months poststroke, nor an MRI at the 3 months follow-up. It would be nice to have had behavioral assessment with brain images at the same time because a lot can happen in weeks, let alone months after a stroke.

Nevertheless, the authors used a novel way to look at the brain pictures, called voxel-based lesion-symptom mapping (VLSM). Well, is not really novel, it’s been around for 15 years or so. Basically, to ascertain the function of a brain region, researchers either get people with a specific brain lesion and then look for a behavioral deficit or get a symptom and then they look for a brain lesion. Both approaches have distinct advantages but also disadvantages (see Bates et al., 2003). To overcome the disadvantages of these methods, enter the scene VLSM, which is a mathematical/statistical gimmick that allows you to explore the relationship between brain and function without forming preconceived ideas, i.e. without forcing dichotomous categories. They also looked at voxel-based morphometry (VBM), which a fancy way of saying they looked to see if the grey and white matter differ over time in the brains of their subjects.

After much analyses, Sihvonen et al. (2016) conclude that the damage to the right hemisphere is more likely conducive to amusia, as opposed to aphasia which is due mainly to damage to the left hemisphere. More specifically,

“damage to the right temporal areas, insula, and putamen forms the crucial neural substrate for acquired amusia after stroke. Persistent amusia is associated with further [grey matter] atrophy in the right superior temporal gyrus (STG) and middle temporal gyrus (MTG), locating more anteriorly for rhythm amusia and more posteriorly for pitch amusia.”

The more we know, the better chances we have to improve treatments for people.

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unless you’re left-handed, then things are reversed.

References:

1. Sihvonen AJ, Ripollés P, Leo V, Rodríguez-Fornells A, Soinila S, & Särkämö T. (24 Aug 2016). Neural Basis of Acquired Amusia and Its Recovery after Stroke. Journal of Neuroscience, 36(34):8872-8881. PMID: 27559169, DOI: 10.1523/JNEUROSCI.0709-16.2016. ARTICLE  | FULLTEXT PDF

2.Bates E, Wilson SM, Saygin AP, Dick F, Sereno MI, Knight RT, & Dronkers NF (May 2003). Voxel-based lesion-symptom mapping. Nature Neuroscience, 6(5):448-50. PMID: 12704393, DOI: 10.1038/nn1050. ARTICLE

By Neuronicus, 9 November 2016

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The FIRSTS: The Name of Myelin (1854)

One reason why I don’t post more often is that I have such a hard time deciding what to cover (Hint: send me stuff YOU find awesome). Most of the cool and new stuff is already covered by big platforms with full-time employees and I try to stay away of the media-grabbers. Mostly. Some papers I find so cool that it doesn’t matter that professional science journalists have already covered them and I too jump on the wagon with my meager contribution. Anyway, here is a glimpse on how my train of thought goes on inspiration-less days.

Inner monologue: Check the usual journals’ current issues. Nothing catches my eye. Maybe I’ll feature a historical. Open Wikipedia front page and see what happened today throughout history. Aha, apparently Babinski died in 1932. He’s the one who described the Babinski’s sign. Normally, when the sole of the foot is stroked, the big toe flexes inwards, towards the sole. If it extends upwards, then that’s a sure sign of neurological damage, the Babinski’s sign. But healthy infants can have that sign too not because they have neurological damage, but because their corticospinal neurons are not fully myelinated. Myelin, who discovered that? Probably Schwann. Quick search on PubMed. Too many. Restrict to ‘history”. I hate the search function on PubMed, it brings either to many or no hits, no matter the parameters. Ah, look, Virchow. Interesting. Aha. Find the original reference. Aha. Springer charges 40 bucks for a paper published in 1854?! The hell with that! I’m not even going to check if I have institutional access. Get the pdf from other sources. It’s in German. Bummer. Go to Highwire. Find recent history of myelin. Mielinization? Myelination? Myelinification? All have hits… Get “Fundamental Neuroscience” off of the shelf and check… aha, myelination. Ok. Look at the pretty diagram with the saltatory conduction! Enough! Go back to Virchow. Does it have pictures, maybe I can navigate the legend? Nope. Check if any German speaking friends are online. Nope, they’re probably asleep, which is what I should be doing. Drat. Refine Highwire search. Evrika! “Hystory of Myelin” by Boullerne, 2016. Got the author manuscript. Hurray. Read. Write.

Myelinated fibers, a.k.a. white matter has been observed and described by various anatomists, as early as the 16th century, Boullerne (2016) informs us. But the name of myelin was given only in 1854 by Rudolph Virchow, a physician with a rich academic and public life. Although Virchow introduced the term to distinguish between bone marrow and the medullary substance, paradoxically, he managed to muddy waters even more because he did not restrict the usage of the term mylein to … well, myelin. He used it also to refer to substances in blood cells and egg’s yolk and spleen and, frankly, from the quotes provided in the paper, I cannot make heads or tails of what Virchow thought myelin was. The word myelin comes form the Greek myelos or muelos, which means marrow.

Boullerne (2016) obviously did a lot of research, as the 53-page account is full of quotes from original references. Being such a scholar on the history of myelin I have no choice but to believe her when she says: “In 1868, the neurologist Jean-Martin Charcot (1825-1893) used myelin (myéline) in what can be considered its first correct attribution.”

So even if Virchow coined the term, he was using it incorrectly! Nevertheless, in 1858 he correctly identified the main role of myelin: electrical insulation of the axon. Genial insight for the time.

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I love historical reviews of sciency stuff. This one is a ‘must-have’ for any biologist or neuroscientist. Chemists and physicists, too, don’t shy away; the paper has something for you too, like myelin’s biochemistry or its birefringence properties.

Reference: Boullerne, AI (Sep 2016, Epub 8 Jun 2016). The history of myelin. Experimental Neurology, 283(Pt B): 431-45. doi: 10.1016/j.expneurol.2016.06.005. ARTICLE

Original Reference: Virchow R. (Dec 1854). Ueber das ausgebreitete Vorkommen einer dem Nervenmark analogen Substanz in den thierischen Geweben. Archiv für pathologische Anatomie und Physiologie und für klinische Medicin, 6(4): 562–572. doi:10.1007/BF02116709. ARTICLE

P.S. I don’t think is right that Springer can retain the copyright for the Virchow paper and charge $39.95 for it. I don’t think they have the copyright for it anyway, despite their claims, because the paper is 162 years old. I am aware of no German or American copyright law that extends for so long. So, if you need it for academic purposes, write to me and thou shall have it.

By Neuronicus, 29 October 2016

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