- August 14, 2009
- 11:43 PM
- 741 views
On Photoaging of Skin
by Reason in Fight Aging!
The latest issue of the Journal of Investigative Dematology Symposium Proceedings includes a set of papers theorizing on the mechanisms by which exposure to sunlight accelerates the characteristic ways in which skin changes with age. In many ways its a good illustration of just how far there is to go in pulling together present knowledge of aging biochemistry into theories that are both unifying and specific: the researchers here argue on mechanisms from a number of quite different and distinct viewpoints. Some of the papers are presently free to read, so take a look while that lasts. Telomere-Mediated Effects on Melanogenesis and Skin Aging UV-induced melanogenesis (tanning) and "premature aging" or photoaging result in large part from DNA damage. This article reviews data tying both phenomena to telomere-based DNA damage signaling and develops a conceptual framework in which both responses may be understood as cancer-avoidance protective mechanisms. Role of Mitochondria in Photoaging of Human Skin: The Defective Powerhouse Model The exact pathogenesis of photoaging of the skin is not yet known. Earlier, a number of molecular pathways explaining one or more characteristics of photoaged skin have been described, but a unifying mechanistic concept is still missing. Here we propose the...... Read more »
Krutmann, J., & Schroeder, P. (2009) Role of Mitochondria in Photoaging of Human Skin: The Defective Powerhouse Model. Journal of Investigative Dermatology Symposium Proceedings, 14(1), 44-49. DOI: 10.1038/jidsymp.2009.1
- August 14, 2009
- 07:05 PM
- 1,074 views
Did knuckle-walking evolve twice?
by zinjanthropus in A Primate of Modern Aspect
Knuckle-walking is a pretty special mode of locomotion. Amongst primates, only the African apes do it habitually, and anteaters are the only other mammal who does it. It would seem, then, that the most parsimonious explanation for such a specialized form of locomotion would be that the African apes all share a common [...]... Read more »
Kivell, T., & Schmitt, D. (2009) Independent evolution of knuckle-walking in African apes shows that humans did not evolve from a knuckle-walking ancestor. Proceedings of the National Academy of Sciences. DOI: 10.1073/pnas.0901280106
RENDALL, D., & DIFIORE, A. (2007) Homoplasy, homology, and the perceived special status of behavior in evolution. Journal of Human Evolution, 52(5), 504-521. DOI: 10.1016/j.jhevol.2006.11.014
Dainton, M., & Macho, G. (1999) Did knuckle walking evolve twice?. Journal of Human Evolution, 36(2), 171-194. DOI: 10.1006/jhev.1998.0265
- August 14, 2009
- 04:54 PM
- 520 views
The bat and the moth, and the ant and the butterfly
by Sunil in Balancing life
What better way to resume blogging after a break than with a couple of fascinating stories from the natural world, about predator and prey, defensive arms races and survival cues?Bats invoke a variety of emotions from people, ranging from disgust and (unfounded) fear to “they’re cool”. At least the Batman sometimes did some good in helping kids get rid of their fear or paranoia of bats. But while bats might look like silly rats with wings, they are indeed supremely efficient hunting machines. While some bats eat fruit, a majority of them hunt flying insects in the dark, and eat vast quantities of moths, locusts, flies, mosquitoes and any other bug that flies. In order to do this efficiently in the dark, they have a fabulously developed system of “echolocation”, a better sonar system than most battleships. This is great for the bat, and allows them to locate flying insects with pin-point accuracy. But what about the insects? Obviously, they have a pressing need to survive and need to escape bats. Therefore many insects have evolved remarkable ways to evade their hunters.Some insects have developed evasive flying maneuvers, others just taste bad and the bats learn to avoid them, while others yet have evolved a neuronal auditory system that can detect the bat sonar frequency and allow them to escape. So there is this constant fight between bat and insect in evolving better sonar or ways to evade it. But, taking a cue from standard defense technology, do any insects actually jam or disrupt bat sonar? It appears that a certain species of tiger moth can do precisely this.The tiger moth is a perfectly edible snack for the echolocating bat. But some tiger moths emit specific ultrasonic clicks in the presence of attacking bats. These clicks could potentially serve as a warning sound, or perhaps be used to startle bats (thus giving the moth time to escape), or perhaps affect the bat sonar. A group of researchers decided to investigate this phenomenon in a tiger moth species called B. trigona, and used an ingenious test to determine what role these ultrasonic clicks were playing. They pitted moths against bats in a closed chamber and precisely observed what the bats did. If the click was a warning sound (for say a poisonous or distasteful insect), the bat would at first attack the insect, but drop it or spit it out, and then learn to avoid the insect. If it was a startling sound, the bat would at first be startled, but would learn to avoid it. If the click was indeed a sonar jamming sound, the bats would continue to be confused by the clicking over time. In their experiments, the researchers used a bunch of juvenile or adult bats and presented them with either the clicking moths, or other moths of the same size that didn’t click, or just a different type of edible, non-clicking moth. What they found was fascinating. The bats indeed did eat the clicking moths. However, the bats were 400% more likely to eat a non-clicking moth than the clicking B. trigona. But what if these clicking moths just tasted worse? To make sure that this wasn’t the case, the researchers disrupted the clicking mechanisms of these moths, and then let them out with the bats. This time, the bats hunted them down as well as the other non-clicking moths. It became very apparent that the moths used the clicking sound in order to disrupt the bat sonar.As far as the moths go, the evolutionary race for survival is pretty simple. Out in the wild, they don’t need to develop a fantastic sonar jamming device to completely disrupt the bat sonar. All they need to do to get a huge survival edge is to be able to disrupt the bat echolocator just a little bit (but more than any other insect around), so that they can get away and the other insect gets eaten. To do this, they only needed to develop a simple tymbal structure, and this structure is now widespread amongst some tiger moth species. And by doing that, they haven’t evolved to escape all bats, but have just enough to gain that much needed survival edge over other bat prey.(Original reference: Corcoran, A., Barber, J., & Conner, W. (2009). Tiger Moth Jams Bat Sonar Science, 325 (5938), 325-327 DOI: 10.1126/science.1174096)**********This next story is just as fascinating, though more incomplete and raising more questions. Plants obviously are under constant risk of being eaten by some herbivore or the other. So some plants have a very effective defense strategy. They secrete sugars onto their stem or leaves so that they can attract ants. These ants then stay on the plant, and serve as a nice, natural defense against other plant eating insects or animals. Butterflies, on the other hand, are insects that plants share a love-hate relationship with. On one hand, the butterfly pollinates the flowers, allowing the transfer of genetic material from one plant to the other, thus enabling reproduction. On the other hand, butterflies lay their eggs on plant leaves and the caterpillars then devour the leaves. And for the butterfly itself, the last place it wants to lay eggs on is a leaf full of predatory ants which would eat up the eggs or caterpillars.But can a butterfly, a mere non-thinking insect, know not to lay eggs on leaves with ants? The answer, surprisingly, is yes. In this little paper in The American Naturalist, some researchers devised ingenious experiments to see if butterflies would distinguish between leaves that had ants, or didn’t have ants on them, in order to decide which leaves to lay their eggs on. In their experiment, the researchers took dead specimens of three species of ants, two of which were predatory (and would eat the eggs/caterpillars) and one of which was a bug of a similar size and shape, but a harmless herbivores. Then, they pinned these ants on different leaves, and let the butterflies decide where they laid their eggs. What they saw was surprising, to say the least. The butterflies not only avoided the leaves with the predatory ants, but also didn’t mind laying eggs on the leaves which had the harmless bug on them. So it wasn’t as if the butterfly was just laying eggs on leaves with no ants on them, but actually seemed to know that laying eggs on leaves with the herbivorous bug wouldn’t hurt their eggs and so ignored the innocuous bug. Clearly, it appears that butterflies can use visual clues and decide where to lay their eggs.What is particularly fascinating to me though is not the fact that butterflies can distinguish between predatory and non-predatory ants, but the fact that they know how to do so without any prior “training”. After all, butterflies are far away from animals or birds which care for their young and potentially teach them about predators or food. Butterflies aren’t even social insects, to have groups to collectively “learn” from. So what is the internal wiring they are born with that tells them some ants are dangerous, while others aren’t? What neuronal and signaling pathways do visual cues of predatory ants activate, while those of innocuous bugs do not? And how does that happen? Do other things, like smell, also influence the butterflies? There is a whole world of questions out there, waiting to be answered. Original reference: Sendoya, S., Freitas, A., & Oliveira, P. (2009). Egg‐Laying Butterflies Distinguish Predaceous Ants by Sight The American Naturalist, 174 (1), 134-140 DOI: 10.1086/599302)
... Read more »
Corcoran, A., Barber, J., & Conner, W. (2009) Tiger Moth Jams Bat Sonar. Science, 325(5938), 325-327. DOI: 10.1126/science.1174096
Sendoya, S., Freitas, A., & Oliveira, P. (2009) Egg‐Laying Butterflies Distinguish Predaceous Ants by Sight. The American Naturalist, 174(1), 134-140. DOI: 10.1086/599302
- August 14, 2009
- 03:37 PM
- 618 views
Implicit-memory involved in accurate responding on recognition test
by William Lu in The Quantum Lobe Chronicles
There is a common assumption that accurate recognition exclusively reflects explicit-memory processing. However, Voss and Paller seem to have turned this notion on its head. In their study they found that implicit-memory processes can in fact guide responses in an explicit recognition test. Kaleidoscope images were used to either divide or keep intact the human subject's attention. These same images were then discriminated from visually similar foils during forced-choice recognition testing. They found higher accuracy for images studied with divided attention than for images studied with no attentional diversion. Surprisingly, "guess" responses were even more accurate than "know" responses. Moreover, metamemory was disrupted during the divided attention condition. ERPs of 200-400ms were observed for correct guesses which have been attributed to implicit-memory processing in past studies. The authors suggest that implicit-memory processing to recognition may have been enhanced due to reduced potential for explicit-memory processing. They conclude by stating that their study "provides an unprecedented demonstration of the distinctive nature of overt recognition derived from unconscious memory, a phenomena that we describe as ‘implicit recognition.’"Voss JL, & Paller KA (2009). An electrophysiological signature of unconscious recognition memory. Nature neuroscience, 12 (3), 349-55 PMID: 19198606... Read more »
Voss JL, & Paller KA. (2009) An electrophysiological signature of unconscious recognition memory. Nature neuroscience, 12(3), 349-55. PMID: 19198606
- August 14, 2009
- 03:07 PM
- 860 views
Connectivity patterns between Broca's area and the temporal lobe
by Greg Hickok in Talking Brains
There have now been a sufficient number of in vivo tractography studies of language-related areas to discern the general patterns of connectivity between Broca's area and the temporal lobe. In vivo tractography is achieved using diffusion tensor imaging (DTI) which is sensitive to the direction (orientation) of water molecule diffusion. Because water diffuses more readily along myelinated fiber tracts DTI can be used to map white matter fiber projections. Like fMRI, DTI findings are highly dependent on the details of how the data are analyzed, e.g., how the seeds are selected, whether you average across subjects or not, etc. So, like fMRI I think any individual study needs to be interpreted cautiously until similar patterns start showing up across studies/labs/methods. I recently looked at four published studies to see if there were any patterns that emerged. The figure below is my summary of what these studies showed. All of them distinguished between anterior and posterior sectors of Broca's area, the pars triangularis (PTr, ~BA45) and pars opercularis (PO, ~BA44), and two studies distinguished a third region referred to as the deep frontal operculum (DFO). It is not yet clear to me where this DFO is exactly; more on that later. Two of the studies differentiated temporal lobe regions into a dorsal site, the superior temporal gyrus (STG) and a more ventral site, the middle temporal gyrus (MTG). There is clear evidence for two pathways, a dorsal pathway corresponding to the classic arcuate fasciculus link between Broca's and Wernicke's areas, and a ventral pathway that projects through the anterior temporal lobe and into the inferior frontal gyrus via the uncinate fasciculus and/or the extreme capsule. The figure below shows the dominant connections reported in each study. Lines are color coded by study so that where there are more lines between two regions we can have more confidence that the connection exists (i.e., it replicated across more studies). For studies that didn't report a specific temporal lobe target, the lines to the temporal regions are left undetermined in the figure. There is clear evidence for a link between the STG and PO, the posterior portion of Broca's area. This makes some sense as both the STG and PO have been implicated in phonological-level processing. This link appears to be via the dorsal route. One study found that this relation may be mediated by a region in the inferior parietal lobe (IPL). It is tempting to think this may be Spt, but it is only one study, and this study did not specify the specific temporal lobe target. The pars triangularis has a different connectivity pattern. It has projections via both the dorsal and ventral route and where specified, it connects to the MTG. This also makes some sense as both the PTr and the MTG have been implicated in aspects of higher-level (e.g., "semantic") processing. The deep frontal operculum appears to connect with the temporal lobe primarily via the ventral route. Some have suggested that the DFO plays a role in syntactic processes. I'm not so sure about this yet, but it is interesting that it projects through the anterior temporal region which also seems to supports some aspect of sentence-level processing. So what we seem to have is a hierarchical connection pattern between the temporal lobe and inferior frontal lobe. Temporal lobe regions that are closer to the auditory periphery connect with IFG regions that (may be) closer to the motor periphery (the STG-PO circuit), whereas temporal lobe regions that are doing some higher-order operations connect with higher-order IFG regions (the MTG-PTr circuit). I think connectivity studies are crucially important in helping to constrain theories of language organization. While tractography research is still in its infancy, this set of studies strikes me as a really great start. Red: Catani, et al. 2005Blue: Glasser & Rilling, 2008Green: Anwander, et al., 2007Orange: Saur, et al., 2008ReferencesAnwander, A., Tittgemeyer, M., von Cramon, D., Friederici, A., & Knosche, T. (2006). Connectivity-Based Parcellation of Broca's Area Cerebral Cortex, 17 (4), 816-825 DOI: 10.1093/cercor/bhk034Catani, M., Jones, D., & ffytche, D. (2005). Perisylvian language networks of the human brain Annals of Neurology, 57 (1), 8-16 DOI: 10.1002/ana.20319Glasser MF, & Rilling JK (2008). DTI tractography of the human brain's language pathways. Cerebral cortex (New York, N.Y. : 1991), 18 (11), 2471-82 PMID: 18281301Saur, D., Kreher, B., Schnell, S., Kummerer, D., Kellmeyer, P., Vry, M., Umarova, R., Musso, M., Glauche, V., Abel, S., Huber, W., Rijntjes, M., Hennig, J., & Weiller, C. (2008). Ventral and dorsal pathways for language Proceedings of the National Academy of Sciences, 105 (46), 18035-18040 DOI: 10.1073/pnas.0805234105... Read more »
Anwander, A., Tittgemeyer, M., von Cramon, D., Friederici, A., & Knosche, T. (2006) Connectivity-Based Parcellation of Broca's Area. Cerebral Cortex, 17(4), 816-825. DOI: 10.1093/cercor/bhk034
Catani, M., Jones, D., & ffytche, D. (2005) Perisylvian language networks of the human brain. Annals of Neurology, 57(1), 8-16. DOI: 10.1002/ana.20319
Glasser MF, & Rilling JK. (2008) DTI tractography of the human brain's language pathways. Cerebral cortex (New York, N.Y. : 1991), 18(11), 2471-82. PMID: 18281301
Saur, D., Kreher, B., Schnell, S., Kummerer, D., Kellmeyer, P., Vry, M., Umarova, R., Musso, M., Glauche, V., Abel, S.... (2008) Ventral and dorsal pathways for language. Proceedings of the National Academy of Sciences, 105(46), 18035-18040. DOI: 10.1073/pnas.0805234105
- August 14, 2009
- 12:30 PM
- 1,359 views
Dishonesty and Emotion have a Stronger Link than We Think
by David DiSalvo in Neuronarrative
Let’s say that you work in an office with several people, and everyone is expected to meet certain performance standards. You’re an outstanding performer, considered one of the best in the firm. A couple offices down from you is a guy named Wendel, and you feel sorry for Wendel because he’s not quite able to meet the performance standards and is always teetering on the edge of losing his job. Your sense of Wendel is that he’s a good guy who just never gets the right breaks, and if he were given more chances to succeed he could probably pull himself out of his slump.
One day, you’re working on a project team with Wendel and notice that he’s screwed up a major report bigtime—big enough that he’s sure to get fired if anyone else sees it—but so far only you have seen it and you have a brief opportunity to cover up Wendel’s mistakes. If you cover them up, in effect lying by passing off your work as Wendel’s, you’ll probably get away with it and Wendel will go on to work another day. If you don’t, he’s finished.
What will you do?
... Read more »
Gino, F., & Pierce, L. (2009) Dishonesty in the Name of Equity. Psychological Science. DOI: 10.1111/j.1467-9280.2009.02421.x
- August 14, 2009
- 12:06 PM
- 672 views
Chinese coal demand will kill us all, maybe
by Henrik Karlstrøm in STS Guru
Interesting stuff on China's coal demand and GDP growth in this article in Energy Policy. Especially interesting are the implications regarding the trustworthiness of the reports and predictions of the large energy institutions of the world. But first, to quote from the abstract:
"[T]his paper demonstrates that even with conservative assumptions about Chinese GDP growth and income elasticity of electric demand to 2025, the country will likely experience much higher coal demand and emit much greater volumes of carbon dioxide than forecast by various international energy agencies."... Read more »
Shealy, M., & Dorian, J. (2009) Growing Chinese coal use: Dramatic resource and environmental implications. Energy Policy. DOI: 10.1016/j.enpol.2009.06.051
- August 14, 2009
- 10:45 AM
- 833 views
Making sense of changing risk predictions from personal genomics
by dgmacarthur in Genetic Future
Mihaescu, R., van Hoek, M., Sijbrands, E., Uitterlinden, A., Witteman, J., Hofman, A., van Duijn, C., & Janssens, A. (2009). Evaluation of risk prediction updates from commercial genome-wide scans Genetics in Medicine, 11 (8), 588-594 DOI: 10.1097/GIM.0b013e3181b13a4fCaroline Wright from the Public Health Genomics Foundation has a concise post describing the results from a recent paper in Genetic Medicine. The paper evaluates the probability that personal genomics customers will find that their predicted risk of a common disease changes significantly over time as their genetic data are updated, using data on known type 2 diabetes risk variants as a case study. Read the rest of this post... | Read the comments on this post...
... Read more »
Mihaescu, R., van Hoek, M., Sijbrands, E., Uitterlinden, A., Witteman, J., Hofman, A., van Duijn, C., & Janssens, A. (2009) Evaluation of risk prediction updates from commercial genome-wide scans. Genetics in Medicine, 11(8), 588-594. DOI: 10.1097/GIM.0b013e3181b13a4f
- August 14, 2009
- 09:00 AM
- 871 views
The Reality of the Brain-Computer Interface
by Shaheen Lakhan in Brain Blogger
Imagine having the ability to turn on the television and change the channel without using a remote control or typing emails using just the power of your thoughts. Even behind the media hype, brain-computer interface technology may someday restore communication and mobility in persons with disabling diseases.... Read more »
Velliste M, Perel S, Spalding MC, Whitford AS, & Schwartz AB. (2998) Cortical control of a prosthetic arm for self-feeding. Nature, 453(7198), 1098-1101. DOI: 10.1038/nature06996
- August 14, 2009
- 08:41 AM
- 1,492 views
Bipedalism: From the ground-up or trees-down?
A male western gorilla (Gorilla gorilla), photographed at the Bronx Zoo.
The origin of human bipedalism has long been a hot topic among paleoanthropologists. At the very least it is seen as something of a marker for the emergence of the first hominin, yet it remains unclear whether the earliest hominins evolved from a terrestrial, knuckle-walking ancestor or a more arboreal ape. A common interpretation is that since our closest living relatives, gorillas and chimpanzees, are both knuckle-walkers then the first hominins, too, evolved from a knuckle-walking ancestor. As Tracy Kivell and Daniel Schmitt explain in a new PNAS paper, though, this idea may overlook subtle differences between chimpanzees and gorillas that may help us understand the evolution of the earliest hominins.
Gorillas are physically larger than chimpanzees, so it might be expected that they would have more rigid wrists that would help stabilize them as they walked around on their knuckles. This is not what Kivell and Schmitt found. Not only did gorillas have a much greater range of wrist motion than chimpanzees, but it was the chimpanzees that had adaptations in their wrists to increase stability. Despite being more terrestrial and knuckle-walking on the ground more often gorillas actually showed fewer "classic" knuckle-walking adaptations in their wrist bones than chimpanzees did! Read the rest of this post... | Read the comments on this post...... Read more »
Kivell TL, & Schmitt D. (2009) Independent evolution of knuckle-walking in African apes shows that humans did not evolve from a knuckle-walking ancestor. Proceedings of the National Academy of Sciences of the United States of America. PMID: 19667206
- August 14, 2009
- 08:40 AM
- 844 views
How does your brain work out what’s alive?
by Jacob Aron in Just A Theory
Picture a dog playing with a ball. The dog is alive, and the ball is inanimate. Obvious stuff, but how do we know? You might think our brains use visual cues to sort the living from the non-living, but research published in the journal Neuron this week proves it’s a little more complicated.
A team of [...]... Read more »
Mahon, B., Anzellotti, S., Schwarzbach, J., Zampini, M., & Caramazza, A. (2009) Category-Specific Organization in the Human Brain Does Not Require Visual Experience. Neuron, 63(3), 397-405. DOI: 10.1016/j.neuron.2009.07.012
- August 14, 2009
- 07:30 AM
- 788 views
On cancer mortality
by iayork in Mystery Rays from Outer Space
[Cancer] mortality has been systematically decreasing among younger individuals for many decades. … the cancer mortality rates for 30 to 59 year olds born between 1945 and 1954 was 29% lower than for people of the same age born three decades earlier. … substantial changes in cancer mortality risk across the life span have been [...]... Read more »
Kort, E., Paneth, N., & Vande Woude, G. (2009) The Decline in U.S. Cancer Mortality in People Born since 1925. Cancer Research, 69(16), 6500-6505. DOI: 10.1158/0008-5472.CAN-09-0357
- August 14, 2009
- 06:55 AM
- 1,183 views
Cancer stem cell breakthrough
by Cancer Research UK in Cancer Research UK - Science Update
It’s always exciting to see headlines about scientific breakthroughs, and today is no exception – we have “Breakthrough found to kill cancer spread”, “Scientists make breakthrough in fight against deadliest cancer cells” and the ambitious “Cancer – The end?”
The headlines came after researchers in Boston, US, discovered a way to target cancer stem cells – [...]... Read more »
Gupta, P., Onder, T., Jiang, G., Tao, K., Kuperwasser, C., Weinberg, R., & Lander, E. (2009) Identification of Selective Inhibitors of Cancer Stem Cells by High-Throughput Screening. Cell. DOI: 10.1016/j.cell.2009.06.034
- August 14, 2009
- 05:48 AM
- 1,923 views
On the Integration of Tactile, Proprioceptive and Visual Signals by the Brain
by Varun in Wissenschaft
The integration of different sensory inputs in the brain is crucial not only for taking appropriate motor actions but also for body perception and awareness of the bodily self. Integration occurs in higher areas in the brain usually in areas belonging to the parietal lobe1) Integrating Vision and Proprioception in Area 5 ( Graziano et. al (2000))Brodmann Area 5 (or Area 5) is part of the parietal cortex in humans, and in monkeys, is a subdivision of the parietal lobe, occupying primarily the superior parietal lobule. Graziano et. al (2000) studied single neuron responses from Area 5 of monkeys. In their experiments, the arm contralateral to the recording site was outstretched. The real arm of the monkey was covered, and instead a realistic fake hand was kept in view. The experimental design was 2 x 22 x 2 experimental design. Cross indicates fixation spot. The gray arm is the fake arm. The real arm is covered in the experiment (Graziano et. al (2000))Single neuron recordings indicated that the firing rate of individual neurons depends not only on the position of the real arm, but also on the position of the fake arm. The neuron is significantly affected by the position of the real arm, firing more when he real arm is to the left. Additionally, the firing rate further increases when the fake arm is also to the left. Single neuron recording from Area 5. The firing rate is maximum when the real and the fake arms are in congruent position (Graziano et. al (2000))2) Integrating Vision and Touch in Ventral Intraparietal Area (Duhamel et. al (1998))The Ventral Intraparietal Area (or VIP) is a discrete area in the depths of the intraparietal sulcus. Duhamel et. al carried out single neuron recordings in the VIP. They found the neurons to possess a bimodal receptive field. Not only did they respond to a combination of visual and tactile stimuli, but the bimodal receptive fields were arranged in an orderly manner.Bimodal receptive fields of VIP neurons (Duhamel et. al (1998))Small central visual receptive fields were associated with small tactile receptive fields on the muzzle, whereas large peripheral receptive fields were associated with large tactile receptive fields on the side of the head or body. The neurons also demonstrated direction selectivity, in the sense that a visual or tactile stimulus moving in one direction was preferred over the other, and this preferred direction of visual and tactile stimuli coincided in the majority of cells. Direction selectivity of VIP neurons (Duhamel et. al (1998))ReferencesGraziano, M. (2000). Coding the Location of the Arm by Sight Science, 290 (5497), 1782-1786 DOI: 10.1126/science.290.5497.1782Duhamel JR, Colby CL, & Goldberg ME (1998). Ventral intraparietal area of the macaque: congruent visual and somatic response properties. Journal of neurophysiology, 79 (1), 126-36 PMID: 9425183 ... Read more »
Graziano, M. (2000) Coding the Location of the Arm by Sight. Science, 290(5497), 1782-1786. DOI: 10.1126/science.290.5497.1782
Duhamel JR, Colby CL, & Goldberg ME. (1998) Ventral intraparietal area of the macaque: congruent visual and somatic response properties. Journal of neurophysiology, 79(1), 126-36. PMID: 9425183
- August 14, 2009
- 02:45 AM
- 2,306 views
Chocolate Consumption Increased in Parkinson’s Disease
by Dr Shock in Dr Shock MD PhD
Chocolate is not an antidepressant. Interaction between chocolate and neurotransmitter systems in the brain, such as serotonin, that contribute to appetite, reward and mood regulation were studied but no antidepressant mechanism of chocolate was found.
Most possible psychoactive substances in chocolate are metabolized in the blood by an enzyme (monoamineoxydase A), these substances are unable to [...]... Read more »
Wolz, M., Kaminsky, A., Löhle, M., Koch, R., Storch, A., & Reichmann, H. (2009) Chocolate consumption is increased in Parkinson’s disease. Journal of Neurology, 256(3), 488-492. DOI: 10.1007/s00415-009-0118-9
- August 14, 2009
- 02:22 AM
- 736 views
Do adults with Asperger syndrome really have ToM?
by William Lu in The Quantum Lobe Chronicles
People with autism are known to lack the ability to automatically attribute mental states to self and others also known as "mindblindness". A result of this impairment is failure on verbally instructed false-belief tasks. However, people with Asperger syndrome, a milder form of autism, seem to pass with flying colors. This presents a problem for the "mindblindness" theory. So do people with Asperger syndrome really have a theory of mind (ToM) contrary to popular theory?Senju, Southgate, White, and Frith decided to take it upon themselves to sort out this confusion. Instead of using verbal instructions, they had adults with Asperger syndrome perform an eye-tracking task that measured the spontaneous ability to mentalize. This entailed subjects to view a scene of an actor first placing a ball into one of two boxes, then having a puppet move the ball to the alternative box unbeknownst to the distracted actor, thus causing a false belief in the actor about the location of the ball. Results showed that the Asperger group showed significantly less looking bias toward the correct window compared to a control group indicating the Asperger group's inability to spontaneously anticipate others' actions in a nonverbal task. It seems that to a certain extent they do lack a ToM. But then how are they able to pass the verbally instructed false-belief task? The authors suggest that compensatory learning is involved.Senju A, Southgate V, White S, & Frith U (2009). Mindblind Eyes: An Absence of Spontaneous Theory of Mind in Asperger Syndrome. Science (New York, N.Y.) PMID: 19608858... Read more »
Senju A, Southgate V, White S, & Frith U. (2009) Mindblind Eyes: An Absence of Spontaneous Theory of Mind in Asperger Syndrome. Science (New York, N.Y.). PMID: 19608858
- August 14, 2009
- 01:04 AM
- 766 views
Eastern vs. Western emoticons
by The Neurocritic in The Neurocritic
Asian Smiley Emoticons Plush - Set Of 6In a study of cultural differences in the recognition of facial expressions......eye movements of 13 Western Caucasian and 13 East Asian people [were recorded] while they observed pictures of expressive faces and put them into categories: happy, sad, surprised, fearful, disgusted, angry, or neutral. The faces were standardized according to the so-called Facial Action Coding System (FACS) such that each expression displayed a specific combination of facial muscles typically associated with each feeling of emotion. They then compared how accurately participants read those facial expressions using their particular eye movement strategies. It turned out that Easterners focused much greater attention on the eyes and made significantly more errors than Westerners did. The cultural specificity in eye movements that they show is probably a reflection of cultural specificity in facial expressions, [Rachael E.] Jack said. Their data suggest that while Westerners use the whole face to convey emotion, Easterners use the eyes more and mouth less. A survey of Eastern versus Western emoticons certainly supports that idea. "Emoticons are used to convey different emotions in cyberspace as they are the iconic representation of facial expressions," Jack said. "Interestingly, there are clear cultural differences in the formations of these icons." Western emoticons primarily use the mouth to convey emotional states, e.g. : ) for happy and : ( for sad, she noted, whereas Eastern emoticons use the eyes, e.g. ^.^ for happy and ;_; for sad. In addition to having their eye movements monitored, the participants in the study of Jack et al. (2009) performed a seven-alternative forced-choice facial expression categorization task (i.e., ‘‘happy,’’ ‘‘surprise,’’ ‘‘fear,’’ ‘‘disgust,’’ ‘‘anger,’’ and ‘‘sadness’’ plus ‘‘neutral’’) with same-race and other-race FACS-coded faces.The results suggested that facial expressions are not as universal as Paul Ekman made them out to be:East Asian observers made significantly more errors when categorizing ‘‘disgust’’ (p less than 0.05) and ‘‘fear’’ (p less than 0.001) than Western Caucasian (WC) observers did. In contrast, WC observers categorized all facial expressions with comparably high accuracy.In East Asian participants disgust was most often confused with anger, and fear was mistaken for surprise -- which happened because of their greater focus on the eyes, as shown in the figure below. Eye fixations on the mouth (in red) were less intense for the East Asians compared to the Western Caucasians, which resulted in less accurate discrimination of surprise vs. fear and disgust vs. anger (shown in the red bars in the bottom two panels).Adapted from Fig 1B (Jack et al.) - Color-coded distributions presented on grayscale sample stimuli show the relative distributions of fixations across face regions. Higher color saturation indicates higher fixation density, shown relative to all conditions. Note that the red ‘‘mouth’’ fixations for EA observers are less intense as compared to WC observers across conditions. Color-coded bars to the left of each face represent the mean categorization accuracy for that condition, with red indicating a significant difference in categorization errors between groups. SR = same race, OR = other race.But are Shrink Rap Roy's Psych Notes for Smilies universal across Eastern and Western psychiatrists? That remains an open question...:-) stable. cont prozac 40mg. f/u 3 mos.:-)) reduce prozac to 20mg. f/u 1mo.:-)))) d/c prozac. add lithium 300 tid. check TSH, creat. f/u 1wk.:-D add depakote. check lithium level, LFTs, CBC. f/u 1wk.:-| stable. cont prozac 40 mg. f/u 1mo.:-( increase prozac to 60mg. f/u 2wk.:'-( add wellbutrin SR 150mg. f/u 1wk.X-( call 911. send to ER. check for OD.See them all!ReferenceJack RE, Blais C, Scheepers C, Schyns PG, Caldara R (2009). Cultural Confusions Show that Facial Expressions Are Not Universal Current Biology. DOI:10.1016/j.cub.2009.07.051
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Jack RE, Blais C, Scheepers C, Schyns PG, Caldara R. (2009) Cultural Confusions Show that Facial Expressions Are Not Universal. Current Biology. info:/
- August 14, 2009
- 12:00 AM
- 767 views
Intervention helps reduce homophobia
by Christian Jarrett in BPS Research Digest
A problem with interventions that use role-playing to beat prejudice is that bigots usually aren't motivated to take the perspective of the groups that they discriminate against. In a new study, Gordon Hodson and colleagues have tested the effectiveness of an unusual alien-themed intervention for reducing homophobia that involves participants taking the perspective of a homosexual person, without really realising that that is what they're doing.Hodson's team tested the homophobic tendencies of 101 heterosexual students and then had 79 of them complete the so-called "Alien-Nation" simulation, whilst the remainder acted as controls and attended a lecture on homophobia. For the Alien-Nation task, the students formed groups of four to five members and imagined landing on an alien planet that's populated by aliens who look exactly like humans, but who don't allow any public displays of affection, and who live in same-sex housing and reproduce by artificial insemination.The participants answered questions about how they would cope with life on the planet and maintain their lifestyles. They also shared plans for how to behave romantically in secret and how to identify other humans. Research assistants then asked the participants whether the situation applied to any real-life groups. The participants failed to recognise the parallel with homosexuality, but the research assistants pointed out the comparison and drew attention to ways that people who are homosexual deal with the constraints of an intolerant society.A re-test of the participants' attitudes towards homosexuality showed that those in the Alien-Nation group were more able to take the perspective of homosexuals, than were the control participants, and this in turn was associated with more empathy towards people who are homosexual, a greater tendency to think of homosexuals and heterosexuals as all belonging to the same category (being human) and ultimately to more positive attitudes towards people who are homosexual. The Alien condition participants' attitudes also remained more positive compared with controls at one week follow-up."The Alien-Nation simulation is easily administered, requires no extensive training, and reduces prejudice," the researchers said.The intervention used in this study is reminiscent of a prize-winning educational DVD called "Homoworld" that was created by the British psychologists Neil Rees and Catherine Butler in 2008. The film depicts a heterosexual couple as they struggle to live in a world dominated by homosexuality._________________________________Hodson, G., Choma, B., & Costello, K. (2009). Experiencing Alien-Nation: Effects of a simulation intervention on attitudes toward homosexuals. Journal of Experimental Social Psychology, 45 (4), 974-978 DOI: 10.1016/j.jesp.2009.02.010
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Hodson, G., Choma, B., & Costello, K. (2009) Experiencing Alien-Nation: Effects of a simulation intervention on attitudes toward homosexuals☆. Journal of Experimental Social Psychology, 45(4), 974-978. DOI: 10.1016/j.jesp.2009.02.010
- August 13, 2009
- 09:30 PM
- 713 views
Cyclization Reactions and Angelmarin Synthesis
by Steve W in Bridgehead Carbons
The first total synthesis of (+)-Angelmarin includes some neat cyclization reactions. They started with Umbelliferone which you can buy, and synthesized angelmarin by way of columbianetin.I'm always curious about where the names of these compounds come from. The systematic names are probably rather cumbersome, so these common names are useful. Umbelliferone is found in plants of the Umbelliferae family - which includes carrots. Also named for plant species, angelmarin was isolated from Angelica pubescens, and columbianetin from Lomatium columbianum.The first cyclization step is a Claisen rearrangement - three bonds all move in a circle, which causes the allyl group to migrate to the aromatic ring. The resulting ketone tautomerizes to the more stable phenol structure.After an olefin cross-metathesis to introduce two methyl groups, the next step was in effect a double cyclization. First a stereoselective Shi epoxidation. Then the epoxide is opened during the second cyclization to form columbianetin.This last cyclization is an an example of a 5-exo-tet cyclization according to Baldwin's Rules for ring formation. The resulting ring is a 5-membered ring. The bond broken to make the new ring is not part of the new ring (exo). And when the new ring is formed, the nucleophile is forming a bond to a tetrahedral atom (tet).To convert columbianetin into the final product required the formation of an ester. This proved to be challenging - many standard esterification strategies either did not work, or it caused side reactions that destroyed the columbianetin portion of the molecule.To get around this, they first converted it to a malonate ester under mild conditions. This was reacted with p-hydroxybenzaldehyde and catalytic piperidine to generate the final product by way of a Doebner-Knoevenagel condensation. In effect building the hydroxycinnamate group instead of adding it as a single piece.Magolan, J., & Coster, M. (2009). Total Synthesis of (+)-Angelmarin The Journal of Organic Chemistry, 74 (14), 5083-5086 DOI: 10.1021/jo900613u... Read more »
Magolan, J., & Coster, M. (2009) Total Synthesis of ( )-Angelmarin. The Journal of Organic Chemistry, 74(14), 5083-5086. DOI: 10.1021/jo900613u
- August 13, 2009
- 07:00 PM
- 912 views
Climate Change and Climate Change Refugees, Part I
by Elements Team in Elements
By: Rosemary Stephen, Elements: Environmental Health Intelligence
Part I:
The Current State
Climate change is a serious global problem resulting in disrupted weather patterns, violent storms, rising global temperatures and rising ocean levels. Climate change is also displacing people; small family groups to whole populations are being forced to leave their homelands due to environmental changes that [...]... Read more »
Rosemary Stephen. (2009) Climate Change and Climate Change Refugees, Part I. Elements: Environmental Health Intelligence. info:/
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