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A new study of the effects of #GlycemicIndex on #BloodSugar and #Insulin levels has found no effect of consuming a diet containing high or low glycemic index foods. It is important to note that in comparing the effects of consuming of high or low glycemic index foods, the subjects in this study were all restricted to a low carbohydrate, fixed-calorie diet. Thus, the authors conclude that these factors (low carbohydrate content and a limited number of calories) are likely more important than the glycemic index of the foods consumed. Translation: this isn’t a free pass to eat all the white bread and sweets that you desire; it DOES mean that as long as you watch what you eat in general, you don’t have to worry about glycemic index. #JAMA via #NYTimes http://jama.jamanetwork.com/article.aspx?articleid=2040224

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In his excellent book, “This is Your Brain on Music”, Dan Levitin makes several compelling arguments for the particular importance of music to human beings. One I have always found to be particularly appealing is based on the relationship between #rhythm, #motorcontrol, and #vocal production. Vocal production is a motor control problem: we must figure out how to modulate muscle activation in order to produce specific sequences of sounds; when we make errors, we adjust our motor output to compensate, and eventually learn to produce specific sounds on demand.Further, specific temporal modulation is key here, if the “temporal sequence” or rhythm of speech production is incorrect, it doesn’t matter if other aspects of control are perfect, sounds are not produced correctly. This work provides a clear link between the importance of rhythmic motor output produced in a time-locked way with an external beat, and two language-related abilities: (1) speech production and reading readiness. The authors of this work tested pre-school children (who had not yet been given formal reading instruction) in the following way: they quantified their ability to hit a conga drum in time with an external rhythm; they then categorized the children as “synchronizers” and “non-synchronizers”. The authors found that the “synchronizers had better perceptual and cognitive language skills than non-synchronizers”. They also measured the #brainstem-evoked electrical activity in response to speech sounds (with external #electrodes), and found that activity evoked in the brainstems of synchronizers “had more precise neural encoding of the speech syllable envelope for all speech stimuli”. #science #neuroscience #music #language #speech #reading #pnas doi:10.1073/pnas.1406219111

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The prevalence of popular media reporting on #gutflora or gut #microbiota means it’s not likely that I have to explain this but in case you don’t know: you are an ecosystem inhabited by a vast array of microorganisms; which ones you’ve got seems to have important implications for #health in several ways. This recently published study set out to examine whether gut flora and the #immune system are affected by #bottle vs. #breast feeding in primates. The authors compared young #rhesus #macaques who had been reared on #infant #formula to those fed breast milk, and found dramatic differences in gut flora composition and in immune system function. Unfortunately, they were not able to control for another difference between the groups: the #monkeys who drank breast milk were of course with their mothers during this period, while those fed formula were not. Thus, while the authors conclude that observed differences between the groups can be attributed to differences in #diet, I would argue that one must find a way to control for maternal contact as well before such a definitive statement can be made. #science #health #SciTranslMed DOI: 10.1126/scitranslmed.3008791

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It’s no problem for humans to #learn something new just by watching a demonstration: a new workout move, or how to dismantle and (it is to be hoped) reconstruct their cell phone. What about other animals? It seems likely that at least other #primates should have this ability, but it has previously been unclear whether social or other cues might influence passing of information. This work shows that #marmosets can learn by watching a #video demonstration. The authors taught two marmosets how to obtain a reward from a mechanical apparatus they dubbed the “Drawian fruit” by either pulling out a drawer, or lifting up a hatch. They took video of the trained animals successfully obtaining reward from a variety of angles, and then exposed other marmosets – who had no contact with the trained individuals – to the video; a control group saw a static image of a marmoset sitting by the apparatus. Of 12/84 animals were successful in obtaining a reward from the Drawian fruit, 11 of these had watched the video and 1 had not, a #statistically significant difference. Though this isn’t the greatest success rate, “The fact that marmosets can learn from two- dimensional images of unfamiliar conspecifics underlines the potent force of social learning in primates, i.e. that individuals may learn from any skilled model, even a virtual conspecific.” #science #animalbehavior #biollett http://dx.doi.org/10.1098/rsbl.2014.0439

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The #NobelPrize in #Physiology or #Medicine has been awarded to John O’Keefe and Edvard I. & May-Britt Moser for their beautiful work on the physiological underpinnings of the #navigation system of the #mammalian brain. After John O’Keefe’s 1976 discovery of #PlaceCells, it was thought that these neurons might be used for generalized navigation. By 2005, however, it had become clear that in addition to representing spatial information, place cells were strongly modulated by #context as well. It was at this time that work from Edvard I. and May-Britt Moser’s #lab showed off the impressive discovery of #neurons in the #EntorhinalCortex known as #GridCells. Similar to place cells, the #spiking activity of grid cells is spatially specific, while place cells are preferentially active in a single portion of an environment, grid cells show a beautifully regular, #tessellated pattern of spatial activation. In the images below, as a rat freely explores a circular enclosure, individual grid cells periodically and regularly become active: the animal’s path is shown on the left in black, and the portions highlighted in red represent locations where a single grid cell had high activity (one per row of circular images). There are grid cells with a diverse set of variations on this triangular tessellation scheme; many different sizes and orientations of grids. It is this more pure position information represented in the dorsocaudal medial entorhinal cortex (#dMEC) that place cells rely on for their exquisite level of spatial specificity. The next challenge (among many)? How do grid cells integrate spatial information coming from different sensory modalities and motor actions into such regular patterns of activity? #Science #Neuroscience #SystemsNeuroscience #Electrophysiology #Naturedoi:10.1038/nature03721

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The #NobelPrize in #Physiology or #Medicine has been awarded to John O’Keefe and Edvard I. & May-Britt Moser for their beautiful work on the physiological underpinnings of the navigation system of the #mammalian brain. In 1976, O’Keefe published this paper showing how some #neurons in #rat #hippocampus are selectively active when the animal is in specific parts of an enclosed environment. For example, in the image below, the hatched area labelled “202-1” (toward the bottom left) is that in which one of these so-called #PlaceCells (cell 202-1) became selectively excited (it was not active when the rat was in other parts of the #maze). This discovery set of a wave of research that led to fundamental breakthroughs in our understandings of navigation and memory. One question raised by O’Keefe’s findings is: what information is used by place cells to define the spatial boundaries of their “place fields”? This question was answered by the #Mosers in 2005 (explained in my next post). #Science #Neuroscience #SystemsNeuroscience #Electrophysiology #ExpNeurol DOI: 10.1016/0014-4886(76)90055-8

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#Melatonin is that stuff you take to help you sleep when you don’t have the good stuff because your mom has some in her medicine cabinet (aka a #neurohormone that regulates sleep and seasonal behavior in vertebrates). However, nearly all forms of life possess this antioxidant #molecule, and it functions to protect cells from oxidative animals across the board. Note that its protective function being so ubiquitous strongly implies that this is its evolutionarily oldest use. So how did a simple protective absorber of harmful stuff end up in a complex signalling cascade regulating sleep? The authors of a recent study have found a heretofore unrecognized role for melatonin that suggests an evolutionary linkage between its function in invertebrates, and its job regulating sleep in vertebrates. Specifically, they found that melatonin regulates something called “diel vertical migration (DVM)”, in which most invertebrates and some fish rise to the surface of lakes and oceans during the night and sink to the depths during the day. Even more specifically, it appears that melatonin’s job is to essentially to turn off the neurons that control “ciliary swimming”, thus its effect on day/night swimming. This is a far “simpler” mechanism than that exhibited by melatonin in regulating our own day/night cycle of behaviors, but far more complex than a being a cellular janitor, thus the intriguing speculation that the mechanism represents an evolutionary stepping stone. #science #evolution #cell 10.1016/j.cell.2014.09.004

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Are you a “pre-crastinator?” A recent study suggests that there may be a bias towards completing simple tasks sooner than is strictly necessary in order to avoid having to remember to do them later. In this series of experiments, subjects were asked to choose one of two buckets to carry to the end of a corridor (see inset schematic-layout). The experimenters varied the relative distance of the two buckets from their destination: sometimes the two were equally far, but more often one was closer to the end than the other. Intuitively, one might expect that people would opt to carry the bucket a shorter distance, meaning they’d select the bucket closer to the end, farther from themselves. However, what the graph below shows is that people were generally biased towards picking a bucket that was closer to them along the corridor, and farther from the end. The graph indicates the probability of selecting the right-hand bucket as a function of the relative distances of both buckets; to the left of the vertical dashed line, the left-hand bucket is closer to the subject’s starting position (and farther from the end of the corridor), and to the right of the dashed line the right-hand bucket is closer. One way of looking at this data is to focus on the data points to the right of the dashed line: there we can see that despite the left-hand bucket being nearer to the end of the corridor, subjects chose the right-hand bucket more than 50% of the time (horizontal dashed line), requiring them to carry the bucket further on average. Thus, people in this study tend to work a bit harder, just to get the job of making a choice out of the way a bit sooner. #science #psychology #precrastination http://pss.sagepub.com/content/25/7/1487

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Sleeping in a cold room (19 Celsius / 66 Fahrenheit) can increase #metabolism and #insulin sensitivity. Researchers had volunteers sleep and eat in a controlled environment for 4 months. In each months, the ambient temperature of their sleeping quarters was kept constant. The sequence of temperatures was: 24C-19C-24C-27C. Seeping in the 19C room had the effects described above, which were abolished by sleeping in the 24C room. #Science #Diabetes http://diabetes.diabetesjournals.org/content/early/2014/06/18/db14-0513