37 posts · 55,779 views
There is a fascinating case study in Current Biology.
de Gelder et al. discuss a patient -- referred to as TN to protect his privacy -- who had two sequential strokes that damaged his brain. The parts of the brain that were damaged included the primary visual cortex in both hemispheres -- rendering the patient blind. However, the patient could still respond to some visual stimuli through a phenomenon called blindsight.
Even more interesting, the patient could still navigate around visual........ Read more »
de Gelder, B., Tamietto, M., van Boxtel, G., Goebel, R., Sahraie, A., van den Stock, J., Stienen, B., Weiskrantz, L., & Pegna, A. (2008) Intact navigation skills after bilateral loss of striate cortex. Current Biology, 18(24). DOI: 10.1016/j.cub.2008.11.002
I don't think I am alone in saying that I often feel a little envy and schadenfreude towards my peers. Science is a particularly competitive business with few remunerative rewards, so a lot of my self-worth is tied to comparisons with my peer's successes and failures. I won't deny being envious when someone gets a Science paper. And while seeing the abject failure of my peers isn't high on my list of priorities, I won't deny the small satisfaction that I get when someone who breezed through t........ Read more »
Takahashi, H., Kato, M., Matsuura, M., Mobbs, D., Suhara, T., & Okubo, Y. (2009) When Your Gain Is My Pain and Your Pain Is My Gain: Neural Correlates of Envy and Schadenfreude. Science, 323(5916), 937-939. DOI: 10.1126/science.1165604
Neurological diseases can be strange in that they often have additional personality effects. If someone gets a cold, they sneeze a bunch but are basically the same person they were before the cold. In contrast, meningitis can include mental status and personality changes in its early stages -- including irritability and sleepiness. When a disease involves the brain, it can change who we are in addition to making us sick.
In this vein, I found this paper in the journal Brain particularly inte........ Read more »
Abe, N., Fujii, T., Hirayama, K., Takeda, A., Hosokai, Y., Ishioka, T., Nishio, Y., Suzuki, K., Itoyama, Y., Takahashi, S.... (2009) Do parkinsonian patients have trouble telling lies? The neurobiological basis of deceptive behaviour. Brain. DOI: 10.1093/brain/awp052
It's amazing what the kids up to these days.
This one comes live from Mount Sinai (my present educational residence). Hubner et al., publishing in Science, use an infectious, fluorescent strain of HIV to watch the virus move from one cell to another. Their results are fascinating and may help us develop better ways to treat the disease. Read the rest of this post... | Read the comments on this post...... Read more »
Hubner, W., McNerney, G., Chen, P., Dale, B., Gordon, R., Chuang, F., Li, X., Asmuth, D., Huser, T., & Chen, B. (2009) Quantitative 3D Video Microscopy of HIV Transfer Across T Cell Virological Synapses. Science, 323(5922), 1743-1747. DOI: 10.1126/science.1167525
Numerous studies have attempted to correlate general intelligence with different anatomical measures. (You might even argue that the phrenologists were working in this vein.) Likewise many studies have attempted to relate intelligence to the function of different brain regions -- using techniques like fMRI or PET scanning. However, relatively few studies have attempted to correlate general intelligence with anatomical features of particular brains regions.
This is important because we know........ Read more »
Karama, S., Ad-Dab'bagh, Y., Haier, R., Deary, I., Lyttelton, O., Lepage, C., & Evans, A. (2009) Positive association between cognitive ability and cortical thickness in a representative US sample of healthy 6 to 18 year-olds. Intelligence, 37(2), 145-155. DOI: 10.1016/j.intell.2008.09.006
Here is a lesson in why defensive medicine should be avoided: it costs a lot, it doesn't help patients, and it has the potential to hurt them. Chou et al. published a study in the Lancet showing that in patients presenting with lower back pain without serious clinical symptoms (more on this in a second) imaging does not improve outcomes. Read the rest of this post... | Read the comments on this post...... Read more »
Roger Chou, Rongwei Fu, John A Carrino, & Richard A Deyo. (2009) Imaging strategies for low-back pain: systematic review and meta-analysis. The Lancet, 373(9662), 463-472. DOI: 10.1016/S0140-6736(09)60172-0
Alzheimer's research is an ongoing field. Although we know a lot more than we used to, we still don't entirely understand why the accumulation of proteins in Alzheimer's disease kills neurons or renders them non-functional. One intriguing part of the explanation may be offered by Varvel et al. who show that the active proteins in Alzheimer's disease (more on this in a second) cause neurons to re-enter the cell cycle in a mouse model of the disease. Read the rest of this post... | Read the comm........ Read more »
N. H. Varvel, K. Bhaskar, A. R. Patil, S. W. Pimplikar, K. Herrup, & B. T. Lamb. (2008) A Oligomers Induce Neuronal Cell Cycle Events in Alzheimer's Disease. Journal of Neuroscience, 28(43), 10786-10793. DOI: 10.1523/JNEUROSCI.2441-08.2008
Smaller chimps may use grooming rather than aggression as a means to rise in their social hierarchy:
The finding was gleaned from 10 years of observing dominant male chimpanzees in Gombe National Park, Tanzania, looking at behaviors they used to compete for alpha male status relative to their size. Analysis showed that larger males relied more on physical attacks to dominate while smaller, gentler males groomed other chimpanzees, both male and female, to gain broad support.
The study focused o........ Read more »
M.W. Foster, I.C. Gilby, C.M. Murray, A. Johnson, E.E. Wroblewski, & A.E. Pusey. (2009) Alpha male chimpanzee grooming patterns: implications for dominance “style”. American Journal of Primatology, 71(2), 136-144. DOI: 10.1002/ajp.20632
Drug companies are not publishing all the trial data that they submit to the FDA, and those trials that are published are more likely to show positive results.
Rising et al. compared all the New Drug Applications (NDAs) (the vehicle for initiating a new clinical trial) given to the FDA in 2001 and 2002 to subsequent published literature. They found that only about 3/4 of the trials were later published in journals, and those that were published were 5 times as likely to show favorable result........ Read more »
Kristin Rising, Peter Bacchetti, & Lisa Bero. (2008) Reporting Bias in Drug Trials Submitted to the Food and Drug Administration: Review of Publication and Presentation. PLoS Medicine, 5(11). DOI: 10.1371/journal.pmed.0050217
A survey of American internists and rheumatologists has revealed that over 50% of them regularly prescribe placebos.
Tilburt et al. surveyed internists and rheumatologists to see whether they were prescribing placebos, and if so how and what kind they were using. The study, published in BMJ, found the following:
679 physicians (57%) responded to the survey. About half of the surveyed internists and rheumatologists reported prescribing placebo treatments on a regular basis (46-58%, depending........ Read more »
J. C Tilburt, E. J Emanuel, T. J Kaptchuk, F. A Curlin, & F. G Miller. (2008) Prescribing "placebo treatments": results of national survey of US internists and rheumatologists. BMJ, 337(oct23 2). DOI: 10.1136/bmj.a1938
I am a little late to this party, but I do want to talk about this paper in Nature Neuroscience.
Moritz et al. implanted an electrode into a monkey's motor cortex. The electrode was designed to only record from a single neuron at a time. Then the output of that cell -- after a little amplification and transformation in a computer -- was connected to a muscle in the monkey's wrist. Finally, the nerves that innervated that muscle were temporarily anesthetized. The monkey was trained to pl........ Read more »
Chet T. Moritz, Steve I. Perlmutter, & Eberhard E. Fetz. (2008) Direct control of paralysed muscles by cortical neurons. Nature. DOI: 10.1038/nature07418
The scientific process is composed of generating hypotheses and testing those hypotheses through experiment. Yet we don't know a whole lot about how about hypothesis generation happens on the level of the brain.
Recognizing that I am dealing with a loaded term -- scientists have strong opinions on the meaning of the term hypothesis -- I would like to talk about a study that looked hypothesis generation in the brain. Kwon et al. used fMRI to look at the brain activation associated with hypot........ Read more »
Y KWON, J LEE, D SHIN, & J JEONG. (2008) Changes in brain activation induced by the training of hypothesis generation skills: An fMRI study. Brain and Cognition. DOI: 10.1016/j.bandc.2008.08.032
One of the problems brains must overcome to behave effectively is to discretely encode all the different responses that they can produce. Considering movement alone, you can move in a lot of different ways. Selecting which one is appropriate is troublesome in itself, but encoding all of them is a challenge. It is like trying to organize the Library of Congress so that you can instantly find exactly what you want. Your brain must come up with some way to encode each of these responses separat........ Read more »
N Sigala, M Kusunoki, I Nimmo-Smith, D Gaffan, & J Duncan. (2008) Hierarchical coding for sequential task events in the monkey prefrontal cortex. Proceedings of the National Academy of Sciences, 105(33), 11969-11974. DOI: 10.1073/pnas.0802569105
Yet another piece of evidence for the futility of abstinence education. Masters et al., publishing in the journal Perspectives on Sexual and Reproductive Health, show that an adolescent's attitude about sex is a much stronger indicator that they will actually have it than their attitudes about abstinence.
The study followed around 300 teenagers from Seattle over a year after interviewing them about their attitudes about sex and abstinence and their intentions to have sex or abstain. They........ Read more »
N Masters, Blair A Beadnell, Diane M Morrison, Marilyn J Hoppe, & Mary Rogers Gillmore. (2008) The Opposite of Sex? Adolescents’ Thoughts About Abstinence and Sex, and Their Sexual Behavior. Perspectives on Sexual and Reproductive Health, 40(2), 87-93. DOI: 10.1363/4008708
Sorry for the light blogging everyone. It has been a busy, busy week.
Some of you may have caught Janet Hyde's latest paper looking at data from the No Child Left Behind Act and math performance in the US. Under the No Child Left Behind Act, states are required to test children for a variety of skills on a yearly basis. The paper looked at math performance across grade-level broken down by gender for 10 states from these tests.
Here is the key graph:
The data includes a measure of eff........ Read more »
J Hyde, S M Lindberg, M C Linn, A B Ellis, & C C Williams. (2008) DIVERSITY: Gender Similarities Characterize Math Performance. Science, 321(5888), 494-495. DOI: 10.1126/science.1160364
Temporal discounting is our tendency to want things now rather than later. In order to encourage us to save money, banks have to offer us a reward in the form of an interest rate. In order to delay gratification, we have to be convinced that the reward in the future is going to be sufficiently large to compensate us for going without.
When economists talk about temporal discounting, they talk about it in terms of what is called the discount rate. The discount rate is the percentage of money ........ Read more »
S KIM, J HWANG, & D LEE. (2008) Prefrontal Coding of Temporally Discounted Values during Intertemporal Choice. Neuron, 59(1), 161-172. DOI: 10.1016/j.neuron.2008.05.010
Human beings use stereotyped facial expressions to identify the feelings of others. We can tell what another person is feeling in part because of how their face looks. However, this says very little about why the particular changes in facial musculature are associated with particular feelings. Why do the eyebrows go up when we are afraid instead of down?
To address this issue, Susskind et al., publishing in Nature Neuroscience, looked at the visual and physiological effects of fearful expres........ Read more »
One of the most interesting aspects of human behavior is our nearly infinite capacity to arrange and coordinate symbols. Think of the symbols that permeate our existence. Paper money has no value in and of itself. A wedding ring is just a band of metal. The progress of the science might even be seen as the creation of an incredibly elaborate super-abstraction from which we can derive novel and testable predictions. Humans beings, in short, are into symbols.
We know, however, that we are no........ Read more »
Elsa Addessi, Alessandra Mancini, Lara Crescimbene, Camillo Padoa-Schioppa, Elisabetta Visalberghi, & Laurie Santos. (2008) Preference Transitivity and Symbolic Representation in Capuchin Monkeys (Cebus apella). PLoS ONE, 3(6). DOI: 10.1371/journal.pone.0002414
Here is an interesting article showing the cross-over between neuropharmacology and decision making. Crockett et al. show that if you use acute tryptophan depletion to lower the levels of serotonin in subjects, they are more likely to reject unfair offers in the ultimatum game. Read the rest of this post... | Read the comments on this post...... Read more »
M Crockett, L Clark, G Tabibnia, M D Lieberman, & T W Robbins. (2008) Serotonin Modulates Behavioral Reactions to Unfairness. Science. DOI: 10.1126/science.1155577
Related to the question of why there is a gap between the genders in math and the sciences is whether there are possible means of remedy. With respect to possible remedies it is often a good idea to look internationally at which countries don't have this problem -- to see what they are doing right.
Guiso et al. used data from the 2003 Programme for International Student Assessment (PISA) which surveyed 15-year-old students from 40 countries who took identical tests in mathematics and read........ Read more »
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