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Archive by category: Interesting Neuroscience

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Nature Network Journal Club: Curbing cocaine addiction using gene therapy

The next installment of the Nature Network Neuroscience group journal club is now live. The paper discusses a potential therapeutic strategy involving the upregulation of the dopamine receptor D2R that may be beneficial in the treatment of cocaine abuse and addiction.

The contributor discussing this paper for the neuroscience group is Áine Duffy, a postdoctoral fellow at Weill-Cornell Medical College in New York. I want to thank Áine for her participation.

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Nature Network Journal Club: Giving sounds the silent treatment

The next installment of the Nature Network Neuroscience group journal club is now live. The paper provides evidence that in unanesthetized animals, sounds are sparsely represented in the auditory cortex.

The contributor discussing this paper for the neuroscience group is Lizzie Buchen, a science writer for Discover Magazine in New York. I want to thank Lizzie for her participation.

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Nature Network Journal Club: Neuronal dynamics mediate efficient coding

The next installment of the Nature Network Neuroscience group journal club is now live. The paper discusses the role for brief adaptation in the improvement of population-based encoding accuracy during sensory information processing.

The contributor discussing this paper for the neuroscience group is Adam Packer, a graduate student at Columbia University in the lab of Rafa Yuste. I want to thank Adam for his participation.

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Nature Network Journal Club: Getting a GRASP on synapse location

The next installment of the Nature Network Neuroscience group journal club is now live. The paper proposes a new strategy to track the location of select synapses using split fluorescent proteins.

The contributor discussing this paper for the neuroscience group is Andrew Hires, a postdoctoral fellow at Janelia Farm Research Campus in the lab of Loren Looger. I want to thank Andrew for his participation.

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Nature Network Journal Club: Sticky matters configuring a synapse

The next installment of the Nature Network Neuroscience group journal club is now live. The paper explores the in vivo function of neurexins in the coordination of pre- and postsynaptic apposition using Drosophila.

The contributor discussing this paper for the neuroscience group is Margaret Ho, a postdoctoral fellow at the Institute of Molecular Biology, Academia Sinica Taiwan in the lab of Cheng-Ting Chien. I want to thank Margaret for her participation.

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Nature Network Journal Club: Drug craving and internal state

The next installment of the Nature Network Neuroscience group journal club is now live. The paper is on the role of insular cortex in drug craving and the behavioral signs of abstinence-related malaise.

The contributor discussing this paper for the neuroscience group is Ben Saunders, a graduate student at the University of Michigan in the lab of Terry Robinson. I want to thank Ben for his participation.

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Nature Network Journal Club: Crossing the threshold to consciousness

The next installment of the Nature Network Neuroscience group journal club is now live. The paper is attempting to understand the neural mechanisms that distinguish between conscious and unconscious processing, and is from a collaborative group in Paris.

The contributor discussing this paper for the neuroscience group is Alfredo Pereira, Jr, an adjunct professor at São Paulo State University. I want to thank Alfredo for his participation.

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Separate but not equal?

If a disease affects men and women differently, does the disease's mechanism differ by sex? My guess would be no. However, a recent article has me wondering. Schizophrenia symptoms, age of onset, and disease course differ in men and women, and some researchers report increased risk of schizophrenia in men relative to women. Now Shifman et al. report a single nucleotide polymorphism (SNP) associated with schizophrenia in women but not men in a recent article in PLoS Genetics.

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Nature Network Journal Club: Special delivery of an anesthetic

The next installment of the Nature Network Neuroscience group journal club is now live. The paper is on selective nociceptor inhibition, from the lab of Clifford Woolf at Harvard.

The contributor discussing this paper for the neuroscience group is Damien Samways, a post-doctoral fellow at St. Louis University in the lab of Terrance Egan. I want to thank Damien for his participation.

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Nature Network Journal Club: Manufacturing new hair cells is for the birds

The next installment of the Nature Network Neuroscience group journal club is now live. The paper focuses on the generation of new hair cells from avian mesenchymal tissue.

The contributor discussing this paper for the neuroscience group is Shelley Batts, a graduate student at the University of Michigan. I want to thank Shelley for her participation.

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Next installment of Nature Network Neuroscience journal club

The next installment of the Nature Network Neuroscience group journal club is now live. The paper is on somatosensory processing in sensory and motor cortex, from the lab of Carl Petersen in Lausanne.

The contributor breaking down the paper for the neuroscience group is Eric Thomson, a post-doctoral fellow at Duke University in the lab of Miguel Nicolelis. I want to thank Eric for his participation in this new endeavor.


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Teaching an old organism new tricks

How many neurons are required for learning and memory? None, according to Saigusa et al., who report basic learning behavior in unicellular amoebae in a recent article in Physical Review Letters.

The amoeba Physarum polycephalum is sensitive to environmental conditions. At room temperature, Physarum move at a constant rate. However, dry air slows the rate of Physarum movement.

The authors puffed dry air on Physarum once an hour for three hours. On the fourth hour, Physarum slowed down, even when no puff of air was delivered. Subsequent hours without air puffs slowly extinguished the periodic slowing of Physarum movement. However, one dry air puff six hours later reactivated the hourly behavior pattern.

These behaviors are consistent with rudimentary learning in higher organisms. Do these data indicate that unicellular organisms can learn? Physarum, like other organisms, have precise biological rhythms set by cellular oscillators. So, Physarum may be particularly sensitive to events occuring at regular intervals, and their periodic slow-down may represent the setting of a biological rhythm. However, rhythms alone do not explain extinction of the behavior in the absence of additional dry air puffs.

Do these data indicate a potential origin for learning, or do they indicate that our definition of learning in complex organisms is too simplistic? I'm a bit torn.

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Monkeys master mental math

Everyone has had that awkward moment at a cocktail party or at the lunch table:

You: Congratulations on the little one; she's beautiful! When was she born?
New mother: Thank you, thank you. Well, let's see, I've kind of lost track, but with today being January 14 and her birthday being December 17...
You: Oh, so she's already 5 weeks old then. Wow!
New Mother: Uhh...no. She is exactly 28 days old.

Although mistaken mental math has embarrassed us all, we humans still reign supreme in the nonverbal representation of numerical values, right? A new study in PLoS aimed to find out by directly comparing rhesus monkeys and college students on the same arithmetic task.

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Learning from your horrible mistakes

Staying on the genetics theme, a recent Science article suggests that a particular variant of the dopamine receptor (D2) causes some people to poorly learn via negative reinforcement. The A1 allele, as this variant is known, has previously been linked to increased vulnerability of addiction.

The researchers recruited volunteers, who performed a learning task while lying in an fMRI machine. Individuals with the A1 allele (at least one copy) were equally successful at selecting a targeted "good" symbol reinforced with positive feedback (the display of a "smiley face") as those individuals completely lacking the A1 allele. However, when the task was changed such that negative reinforcement drove the learning (subjects were asked to avoid the "bad symbol"), those individuals with the A1 allele failed to perform as well as their A1-lacking colleagues.

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"All the News That's Fit to Print" (except the part about potential conflicts of interest)

Since the recent fall-out of the recent NY Times OP-Ed piece discussing the use of fMRI to predict the inclinations and feelings of swing voters is still fresh in our minds, I wanted to simply provide the link to a recent PLoS ONE paper that touches on the general concept of the media reporting on science.

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Antidepressants and caloric restriction, what's the connection?

If it exists, it must be a tenuous link, right? Well, at least in C. elegans, it is definitely not. Linda Buck and colleagues revealed, in a recent Nature article that drugs modulating the serotonin system in the worm can increase lifespan. Caloric restriction has been a well-documented means to enhance longevity in animals ranging from rodents to worms. We have only recently begun to mechanistically understand why eating less allows us to live longer (remember the sirtuin genes?)

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Cells reverting back to their youth

Since we had a long and involved conversation on the role of embryonic stem cells in research, as well as how this issue is politicized by both sides of the debate (with additional discussion here), recent news insists that we post a follow-up on Action Potential.

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Infants inherently interpret intentions?

While we are discussing infants, development and nature vs. nurture, it is fitting that Nature just published a new article describing the social evaluation skills of pre-verbal infants (6-10 months old). In a nicely-designed experiment, researchers allowed infants to view a toy as it was made to climb over an obstacle. Near the top, another toy would either help the first toy complete the ascent, or impede its progress by pushing it back. When then allowed to choose one of the second two toys for playtime, the infants overwhelmingly chose the "helpful" toy over the "hurtful" toy. In addition, infants were much more likely to choose "neutral" toys (ones that neither helped nor hindered the first toy's progress) over hurtful toys and helpful toys over neutral toys. Interestingly, these preference biases evaporated when the eyes (very prominent on the toys) were removed. This suggests that if the babies did not recognize the toys as "individuals", partiality to helpfulness made little sense, and was thus irrelevant.

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Genetic control of intelligence

No, this isn't another post about Jim Watson; the title is just a shameless ploy to draw in the search engine crowd... It is relevant though, as you'll soon see. I've been meaning to talk about this next topic for a couple of weeks now, but have been distracted with unexpected news stories, editorial discussions regarding the review process, etc. A recent study in PNAS has demonstrated a significant interaction between nature and nurture that influences intelligence.

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Patience, fairness and getting the girl.

No, Action Potential is not going to start giving dating advice...yet. I just needed a catch-all title for a catch-all blog entry. After last week's ugly Watson debate, I figured that I would return to research science and have a little fun updating you on some recent primate research. The usual caveat applies to this entry, as with many of mine, that the neuroscience links are tenuous. Of course, that depends on your definition of neuroscience. Since mine is quite broad, it looks like we can proceed.

Continue reading "Patience, fairness and getting the girl." »

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Circular logic?

What causes autism? The lack of answers or even particularly good leads is frustrating to say the least. Not surprisingly, people both within the scientific community and the general public are hungry for answers, and my general opinion is that the more information the better. However, I'm a little puzzled by a report from the British Association for the Advancement of Science's annual Festival of Science.

According to Simon Baron-Cohen's 'extreme male brain' theory, people with autism show extreme versions of behaviors that are normal in men. In general, men tend to empathize less and systematize more than women. These drives are taken to an extreme degree in people with autism, resulting in the behaviors associated with autism, including reduced eye contact and verbal skills and increased repetitive behavior and orderliness, according to Baron-Cohen.

Is the hormone that causes male behaviors involved in autism? At the Festival of Science, Baron-Cohen and Bonnie Auyeng reported that fetal testosterone contributed to 'autistic traits' in normal eight-year-old children. The researchers calculated an 'autism spectrum quotient' from questionnaires about children's social behaviors and cognitive skills completed by their mothers. Fetal testosterone levels recorded eight years earlier accounted for more than 20% of the variability in this quotient.

According to the researchers, these data suggest that elevated testosterone levels in the womb may contribute to traits associated with autism. However, based on the researchers' reasoning, wouldn't an alternative explanation be that fetal testosterone correlates with male-typical behaviors? Animal studies have shown that testosterone produced in the fetal testes masculinizes the brain (allowing male-typical behavioral patterns). Perhaps the present study indicates that male-typical behaviors are graded, with high levels of fetal testosterone producing 'super males'.

While interesting, it's not clear to me that these data are directly relatable to autism. For that, we'll need to see Baron-Cohen's next study, involving clinical data and amniotic samples from 90,000 people with and without autism.

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What kept Einstein smart…

…may have been the fact that he didn’t watch the Baby Einstein videos, distributed by the Walt Disney Company. A recent study by researchers at the University of Washington determined that those babies who regularly watched the supposedly stimulating videos actually scored more poorly on an assessment survey of language development. All research was conducted through phone interviews of over 1,000 parents of children between 2 and 24 months of age.

This has Disney in an uproar. They have challenged the quality of the research, the competence of the researchers, and the intelligence of the University, whose president has chosen to stand by the work and the press release bonanza that this study has created. Why do companies suddenly become experts in basic research only after the emergence of findings against their products? Would this attack on the excellence of the research exist if the opposite outcome had been true, and the videos actually enhanced language skills? Of course not. But that would have made for quite an interesting sticker label on the package –

“****New research determines that Baby Einstein videos enhance language development!!**** (however, we at the Disney Company have reason to believe that this study was conducted in a poor and sloppy manner and the potential remains that this DVD may hinder cognitive growth. Please watch at your own risk)”

It is senseless to debunk a published, peer-reviewed manuscript as non-rigorous without statistics, an independent study, or other credible evidence to back up such accusations just because you disagree with the outcome. However, in the defense of the company, their #1 concern seems to be the inflammatory, and potentially result-distorting, press release that was issued by the University. I agree that parts of that blurb leave much to be desired with regards to the facts (the University must know that very few parents out there are actually going to sit down and read the full article to make their own assessment of the study's merits, especially if they don't have full-access rights to the article.) But upon reading the response of Disney's CEO to this press release, credibility erodes when it begins to look like his "high road" talk against an inaccurate, malicious press release is just a front, allowing him to proceed to bash the article itself. Of course, the president of UW reciprocated.

Disney has started to go down the appropriate path by working with an expert to assist them in interpreting the new findings, but even she was quoted in a Nature news feature as saying:

“"There are some valid conclusions in [the new study] that warrant additional research. I'm cautious, but it makes sense."

Disney should leave the research to the researchers, and the peer-review to the journals. If Disney is truly concerned and dedicated to the education of our youth, instead of fighting such studies, perhaps they should attempt to learn from them and encourage further dialogue amongst child development researchers, allowing both the company and the public to understand the full impact of their product. Meanwhile, one author of the DVD study suggested that watching anything, even American Idol, could be better for juvenile language development than these videos. Well, I don’t intend to encourage my children to watch reality TV anytime soon, but I also won’t be spending $370 on the Baby Einstein box set either. For the record, the American Academy of Pediatrics recommends no television for children under the age of two.

By the way, what ever happened to reading and conversation as language learning tools?

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Politicking for a mate

In Washington DC, coalitions are always formed, with prominent congress(wo)men establishing a staunch public stance on controversial topics, usually to increase their own popularity with certain constituencies, and/or to increase their power. But what about the little-known, junior representative who backs the political giant? What does s/he get? Usually, a nice transportation funding package for the home state, ensuring future votes, or the gratitude of the senior official, perhaps leading to a future seat on an important committee. Well, it seems that chimpanzees operate in much the same way.

Although this won’t be the first time that someone compares Washington politics to monkey business, a new study in Current Biology exposes some of the intricate policies that exist in the world of male dominance amongst chimps. While these great apes may cooperate on a variety of tasks designed to help the colony as a whole, there is a fierce competition amongst the males for dominance and, of course, females. In order to ensure a dominant position, stronger males form coalitions to achieve and maintain status within the group. Once the alpha male is in place, these coalitions are sustained. What is unclear is what benefits the “supporters” derive from protecting and promoting the status of another male.

In the current study, the authors found that when females were ready to mate, the alpha male seized the lion’s share of the opportunities, as expected. Interestingly, they went on to describe that the way other males supported their leader was to protect him during his mating attempts. In return, the alpha male from this particular colony paid in full with the only currency that has long-lasting value to his cohorts: mating opportunities for themselves. The alpha male was much more tolerant of the mating attempts initiated by chimpanzees that supported his own copulatory tendencies the most, and interfered with the reproductive advances made by non-supportive males. It seems that the advantage of even a little access to receptive females is enough of a carrot to entice weaker males to defend Darwinian law and make it easier for the most-fit male to pass on his genes. For the alpha male, the allure and rich compensation of being on top trumps the instinct to fend off every potential rival, leading to the relinquishment of a handful of valuable mating attempts. Therefore, as in Washington, the price of remaining in power for a chimp is to make life easier for your friends and downright miserable for your enemies.

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Another way for the sirtuins to enhance longevity

What do obesity and Parkinson's disease have in common? Strains on our current health care system? Well...yes, but apparently another answer is the sirtuin family of deacetylases. A new study published in Science claims that controlling the activity of sirtuin2 (SIRT2) can be neuroprotective against alpha-synuclein pathology.

The sirtuins are better known for their influence on aging, with many studies demonstrating an increase in the lifespan of several different organisms if these genes are activated. One way to turn on these genes is by stressing an organism, for example through caloric restriction, leading to the activation of SIRT1. SIRT1 can also be directly activated by Resveratrol. Mice that overexpress SIRT1 exhibit several properties associated with a restricted diet, and increased longevity, including low cholesterol, low blood glucose, and low insulin levels. Interestingly, increased SIRT1 expression and/or activity delays the Parkinson's pathology associated with aggregating alpha-synuclein.

SIRT2, another sirtuin family member, is mainly expressed in the brain and is known to be involved with cell cycle regulation, however, the variety of substrates that have been identified for this deacetylase (including tubulin, histones and p53) suggests that it may serve in several cellular capacities. A group at Harvard decided to reduce the expression of SIRT2 through RNAi or small molecule inhibitors, and found that, unlike SIRT1, reduced expression and activity of SIRT2 protected against neuronal cell death in culture and even in a Drosophila model of Parkinson's. Although not completely confirmed, one possibility for the differences discovered regarding the activity levels and neuroprotection between the different sirtuin isoforms is that SIRT1 and SIRT2 act in opposing manners when influencing signaling pathways, with each deacetylase providing checks and balances against the other's actions.

It is exciting that we are beginning to gain an understanding of the signaling systems that influence aging, with the sirtuins exhibiting a knack for extending lifespan, including the maintenance of good health through our digestive systems, and apparently now in our brains. I suspect that we can expect much more from sirtuin research.

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