Check out this website I found at the-scientist.com
Tuesday 24 August 2010
CBC News - Health - Brain wiring key to quick decisions: study
The ability to make quick decisions when they are needed depends on whether your brain connections are the neural equivalent of broadband or dial-up, an international study shows.
In a Proceedings of the National Academy of Sciences paper released online Tuesday, an international team shows flexibility in decision-making is dependent on structural features of the brain.
'As you get older, the bandwidth gets slower and slower.'— Scott BrownQuick decisions tend to be error-prone while relatively slower contemplation tends to produce more accuracy, says one Australian research team member, Scott Brown, an associate professor at the University of Newcastle's cognition laboratory.
This trade-off between speed and accuracy means people need to be able to switch between the fast risky and slower cautious modes of decision-making, as required.
But, says Brown, little is known about the neurology underpinning this flexibility.
Broadband or dial-up?
In their study, Brown and colleagues, which included researchers from the United Kingdom, Germany and the Netherlands, examined what brain mechanisms underpin decision-making flexibility.
They found it was determined by the "purely physical measurement" of the thickness of the connections between the brain's cortex and the striatum of the basal ganglia.
He says the results are the equivalent of brain communication being reliant on a broadband connection or still using dial-up.
"The underlying finding that a purely physical measurement could predict behaviour is very surprising," he says.
Brown says the team has not determined what causes one person's connections to be thicker than another's.
"It could be that it is the 'use it or lose it'" phenomenon, he says.
However, in a paper still under review, Brown says, the team has also shown the connection thins with age.
"As you get older, the bandwidth gets slower and slower," he says.
MRI scans measure fibre thickness
For the study, participants were placed in an MRI scanner and the researchers measured the thickness of "fibres" that carry inputs from the cortex to the basal ganglia.
Brown says the technology allows researchers to "track millimetre by millimetre which direction fibres in the grey matter are travelling," and determine the number (or thickness) of fibres connecting one region to another.
These measurements were done when the participants were not making decisions. They were also required to undertake a series of tasks that required them to make decisions either quickly or slowly.
They found those with the stronger connections in the brain were more able to move flexibly between a fast response and a more accurate slow response.
The study was based on only nine participants, however, the researchers used a previous independent study, which had included MRI scans, to verify their findings.
'Train the brain'
Brown says their work could help in tracking cognitive decline in aging.
"People who have a disease of aging often have their symptoms exacerbated by the slowing that comes with aging," he says.
"If you can understand the slowing, we might be able to separate the effects and better understand what is happening."
He says there is a view that older people are slow and cautious because they choose to be so.
However, these latest findings would suggest that as brain connections thin, the person is "stuck in a regime where response is always slow and cautious."
In current work, Brown says they are trying to force older participants to be faster at decision-making.
"We are seeing if you can train the brain to use these tracks more efficiently," he says.
via cbc.ca
Monday 23 August 2010
Pregabalin and Transcutaneous Electrical Nerve Stimulation for Postherpetic Neuralgia Treatment
Check out this website I found at journals.lww.com
Autism Might Slow Brain's Ability to Integrate Input From Multiple Senses
August 21, 2010 | 10 comments
Autism Might Slow Brain's Ability to Integrate Input From Multiple Senses
A new study found that kids with autism were slower to integrate stimuli from different senses, providing possible explanations for behavioral differences
via rss.sciam.com
Changes in Pain Perception and Descending Inhibitory Controls Start at Middle Age in Healthy Adults
Check out this website I found at journals.lww.com
Delayed chronic fatigue syndrome paper to be published
Cross posted from Nature's The Great Beyond blog.
A highly anticipated paper linking viral infection with chronic fatigue syndrome will at last see the light.
The paper, to be published online later today by Proceedings of the National Academy of Sciences USA (PNAS), is the first to back up a previous report that chronic fatigue syndrome may be linked to infection by a virus called XMRV (see ‘Virus linked to chronic fatigue syndrome’). Chronic fatigue patients and their advocates embraced the findings as a long-sought clue to the cause of the mysterious ailment, but several research teams have since tried and failed to reproduce this link.
The PNAS paper was originally accepted for publication on 27 May. But on 4 June, the authors, who work for the US National Institutes of Health and the US Food and Drug Administration, asked to delay publication while they considered conflicting results from a second paper authored by other government researchers. (For more see ‘Chronic fatigue findings were held back’.) That second paper appeared in the journal Retrovirology on 2 July, but there was still no sign of the first.
Read the rest of the post on The Great Beyond. Or for more background information, check out Nature Medicine’s timeline of the XMRV controversy.
via feeds.nature.com
Friday 6 August 2010
Quantification of the Effects of Transcutaneous Electrical Nerve Stimulation With Functional Magnetic Resonance Imaging: A Double-Blind Randomized Placebo-Controlled Study
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via archives-pmr.org
Pain Physiology Education Improves Pain Beliefs in Patients With Chronic Fatigue Syndrome Compared With Pacing and Self-Management Education: A Double-Blind Randomized Controlled Trial
European Online Customer Service
The Boulevard
Langford Lane, Kidlington
Oxford. OX5 1GB
UK
Hours: Monday - Friday, 8:30am - 5:00pm (Greenwich Mean Time/British Summer Time)
Tel: +44 (0) 1865-843177 (Within Europe)
Fax: +44 (0) 1865-843970
E-mail: eurosupport@elsevier.com
North American and Rest of World Online Customer Service
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Orlando. FL 32887-4800
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via archives-pmr.org
Good to see some further evidence supporting the use of pain education. Clearly understanding pain helps to reduce anxiety and fear in relation.
Tuesday 3 August 2010
Exercise and caloric restriction rejuvenate synapses in lab mice
via sciencedaily.com
Looking at ways of motivating people to undertake exercise, the 'brain effects' could be a seller. Working at the belief level is clearly important in changing behaviours which is after all what exercise is, a behaviour.
Why Do We Have Ten Fingers?
In How Many Limbs Should Humans Have? I described my Limb Law, an empirical law I discovered which relates how long an animal’s limbs are to how many limbs it has. This law is explained by virtue of animals having evolved a limb design that minimizes the amount of needed materials to reach out into the world (see links to my academic work in the previous piece).
To see the Limb Law in action, go to my web site where you can play with an animal’s limb length and watch how the optimal number of limbs changes. Roughly speaking, the animal designs you can create in this program are the ones we find on Earth (…among radially-directed-limbed animals).
The Limb Law applies to more than just animal legs. By “limbs” I refer to any appendages that reach out, and so the hypothesis applies to hands as well, but where a hand’s “limbs” are its digits.
The only thing we must keep in mind in order to apply the Limb Law to hands is that hands are not free-range animals, but are, rather, connected to an animal. Hands have digits pointing away from the arm that connects to the hand, and so have only about half of the digits one would expect if the hand were roaming the world on its own.
In light of this fingers-are-the-hand’s-limbs observation, in this piece I’d like to ask…
Why do we have ten fingers?
In addition to being fundamentally interesting, this question also has deep implications for why we use a base-10 number system (rather than a base-2 or base-8 system, each which would arguably be better).
How can the Limb Law tell us how many fingers we should have, given that it only tells us the relationship between limb length and number of limbs?
Because hands like ours have plausible constraints on how long their fingers should be. Hands must close, i.e., their fingers must be able to reach back over the palm and cover it up. And that simple requirement is enough to enable us to predict roughly how many fingers we should have.
Recall that the Limb Law was that the number of limbs, N≈2π/k, where k was the “limb ratio,” k = L/(L+R), where L is limb length and R the radius of the body.
The demand that finger length be approximately the diameter of the palm means that the finger length should be about twice the palm’s “radius”. So, L≈2R. It follows that k ≈L/[L + (L/2)] = 2/3. And, plugging in k=2/3 into the equation for the number of limbs, N, we have N≈2π/ (2/3) = 3*π ≈ 9.42.
That is, given that fingers must be roughly as long as the diameter of one’s palm, then there should be about 9.42 fingers poking out from the circumference of the palm.
But remember that palms aren’t animals living freely on their own, but are attached to arms, and thus we expect palms to have digits on only about one half of their circumference. So, 9.42 is twice what we should expect for the number of fingers. Divide 9.42 by 2 and we have 4.78 fingers per hand. Or, about five.
Could it be that your run-of-the-mill alien would also have ten fingers, and thus get saddled with base-10?
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There was a healthy discussion when this was posted at Science20.com, and it is worth repeating one exchange here. Here is the comment, followed by my reply…
We have a maximum of 5 digits per limb, because ancient ancestors of all subsequent quadrupeds settled on 5 digits per limb, after initially starting out with a higher number (7 or 8 digits per limb – see for example, http://www.dinosaurjungle.com/prehistoric_animals_acanthostega.php ).
My reply…
The fact that number of digits has tended to only fall among tetrapods (from polydactylous to pentadactylous and lower in many cases) could mean there is some kind of (genetic or developmental) difficulty in adding digits, as you suggest. But abnormal polydactyly is fairly common in vertebrates (including humans), and often has a hereditary component. On this basis it would seem that adding a digit is possible. And, evolution can take more creative approaches as well, like the Giant Panda extra pseudo-digit you mentioned.
Rather than supposing that there is some kind of difficulty in adding digits, or some kind of upper limit of five, an alternative hypothesis is that the original polydactylous tetrapod had simply “too many” digits for most hand designs relevant for terrestrial environments, and that tetrapods ever since have been disproportionately losing digits to fill in vacant spots in design space, with only the occasional added digit. That is, the tendency for digit loss over time may be due to adaptive selection pressures, not a no-adding-digits constraint.
So, I’m not convinced that developmental / genetic constraints force a five digit maximum.
Also, I’m of course not suggesting that prior “evolutionary stages are planning ahead for the number of fingers humans would need in millions of years time.”
And, at any rate, all this is beside the point. Let’s suppose that some kind of historical accident were to force exactly five digits on all progeny of an animal, and that some of those progeny became primates with our hand design. Is it true that it is a historical accident that we have five fingers, in this thought experiment? Not quite. Being stuck with five digits would have constrained the kinds of hand (and body) designs possible for this animal’s progeny. Some hand designs, and animal designs, would then be out of reach to this lineage. The hand designs within reach for such a lineage would be ones which work really well with five digits. …and one such hand design is the “grasper” one where the digit length is of similar length to the palm diameter, very roughly our hand. The question is whether our hand/digit design is optimal in some hypothesized sense. My suggestion is that our 5 digits and our digit-length-to-palm ratio are “designed for one another” (because that relationship is consistent with cheap reaching-out wiring costs). My suggestion is an engineering hypothesis, not a historical hypothesis. If five-ness was historically fixed, then what historically evolved was the length of the digits to become a proper grasping hand. To put it another way, if our long ago ancestors had, say, three fingers, and could not add new ones, then primates would probably not have evolved in the first place, because the hand would have led the lineage down new design paths.
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This first appeared on May 17, 2010, as a feature at Science 2.0
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Mark Changizi is Professor of Human Cognition at 2AI, and the author of The Vision Revolution (Benbella Books) and the upcoming book Harnessed (Benbella Books).
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