brain

On ne sait pas ce que peut le corps

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The new “eyes wide shut” illusion uses a standard enlarging (shaving or makeup) mirror. Close one eye and look at the closed eye in the mirror; the eye should take up most of the mirror. Switch eyes to see the other closed eye. Switch back-and-forth a few times, then open both eyes. You see an open eye. Which eye is it? To find out, close one eye. Whichever you close, that’s the eye you see. How can this be possible? The brain is fusing two images of the two eyes.

{ Perception | Continue reading | Thanks Brad! }

However, no one has hitherto laid down the limits to the powers of the body, that is, no one has as yet been taught by experience what the body can accomplish solely by the laws of nature, in so far as she is regarded as extension. No one hitherto has gained such an accurate knowledge of the bodily mechanism, that he can explain all its functions; nor need I call attention to the fact that many actions are observed in the lower animals, which far transcend human sagacity, and that somnambulists do many things in their sleep, which they would not venture to do when awake: these instances are enough to show, that the body can by the sole laws of its nature do many things which the mind wonders at.

Again, no one knows how or by what means the mind moves the body, nor how many various degrees of motion it can impart to the body, nor how quickly it can move it.

{ Spinoza, Ethics, III, Proposition II, Scholium | Continue reading }

unrelated { eye colour may not be a priority when choosing a partner }

My leaves have drifted from me

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In a study published in Nature Neuroscience on Jan. 21, neuroscientists and systems biologists from Harvard Medical School reveal just how inexorably interwoven nature and nurture are.

Using novel technologies developed at HMS, the team looked at how a single sensory experience affects gene expression in the brain by analyzing more than 114,000 individual cells in the mouse visual cortex before and after exposure to light.

Their findings revealed a dramatic and diverse landscape of gene expression changes across all cell types, involving 611 different genes, many linked to neural connectivity and the brain’s ability to rewire itself to learn and adapt.

The results offer insights into how bursts of neuronal activity that last only milliseconds trigger lasting changes in the brain, and open new fields of exploration for efforts to understand how the brain works.

{ Harvard Medical School | Continue reading }

art { Josef Albers, Hotel Staircase, Geneva, 1929/1932 }

‘The second half of a man’s life is made up of nothing but the habits he has acquired during the first half.’ –Dostoyevsky

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When you’re doing two things at once – like listening to the radio while driving – your brain organizes itself into two, functionally independent networks, almost as if you temporarily have two brains. That’s according to a fascinating new study from University of Wisconsin-Madison neuroscientists Shuntaro Sasai and colleagues.

{ Neuroskeptic | Continue reading }

art { Harri Peccinotti }

‘We are all broken, that’s how the light gets in.’ –Ernest Hemingway

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When one draws a correlation between body mass and brain mass for living primates and extinct species of Homo, it is not humans—whose brains are three times larger than those of chimpanzees, their closest primate relative—that are an outlier. Instead, it is the great apes—gorillas and the orangutan—with brains far smaller than would be expected in relation to their body mass. We are the new normal in evolution while the great apes are the evolutionary oddity that requires explanation.

But we remain special in another way. Our 86 billion neurons need so much energy that if we shared a way of life with other primates we couldn’t possibly survive: there would be insufficient hours in the day to feed our hungry brain. It needs 500 calories a day to function, which is 25 percent of what our entire body requires.

{ New York Review of Books | Continue reading }

art { Christopher Wool, Untitled, 2006 }

Is Wagner a human being at all? Is he not rather a disease?

Neil Harbisson, an artist with colorblindness, has a chip implanted in his head and antenna attached to his skull that allows him to hear a different frequency of sound for each color.

Meanwhile, his artistic partner Moon Ribas has an implanted magnet that allows her to feel the tremors of earthquakes around the world.

{ Quartz | Continue reading }

When you speak, you learn nothing

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Normal aging is known to be accompanied by loss of brain substance.

Machine learning was used to estimate brain ages in meditators and controls.

At age 50, brains of meditators were estimated to be 7.5 years younger than that of controls.

These findings suggest that meditation may be beneficial for brain preservation.

{ NeuroImage | Continue reading }

image { Jonathan Puckey }

‘When we are tired, we are attacked by ideas we conquered long ago.’ —Nietzsche

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Theory of Mind (ToM) is the ability to understand the perspectives, mental states and beliefs of others in order to anticipate their behaviour and is therefore crucial to social interactions.

Although fMRI has been widely used to establish the neural networks implicated in ToM, little is known about the timing of ToM-related brain activity.

We used magnetoencephalography (MEG) to measure the neural processes underlying ToM, as MEG provides very accurate timing and excellent spatial localization of brain processes. We recorded MEG activity during a false belief task, a reliable measure of ToM, in twenty young adults (10 females). […]

Our findings extend the literature by demonstrating the timing and duration of neural activity in the main regions involved in the “mentalizing” network, showing that activations related to false belief in adults are predominantly right lateralized and onset around 100 ms.

{ NeuroImage | Continue reading }

still { Total Recall, 1990 }

‘I have principles. If you don’t like them I have others.’ —Groucho Marx

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264 right-handed, 246 mixed-handed and 360 left-handed students were requested to indicate on five maps of cinema halls what place they would choose. All three handedness groups showed a preference for the right and a corresponding directional bias towards the left space. However, they differed significantly from each other on the magnitude of this bias which was most pronounced in right and less in left handers. […]

It is hypothesized that right, mixed and left handers differ in a large number of behavioral choices and strategies, modeled by cerebrally lateralized mechanisms and that the cinema seating preference is only one of them.

{ Cortex | Continue reading }

still { Jean-Luc Godard, Nouvelle vague, 1990 }

Did she then accept as an article of belief the theory of astrological influences upon sublunary disasters?

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The benefits of mindfulness meditation, increasingly popular in recent years, are supposed to be many: reduced stress and risk for various diseases, improved well-being, a rewired brain. But the experimental bases to support these claims have been few. Supporters of the practice have relied on very small samples of unrepresentative subjects, like isolated Buddhist monks who spend hours meditating every day, or on studies that generally were not randomized and did not include placebo­control groups.

This month, however, a study published in Biological Psychiatry brings scientific thoroughness to mindfulness meditation and for the first time shows that, unlike a placebo, it can change the brains of ordinary people and potentially improve their health. […]

First they recruited 35 unemployed men and women who were seeking work and experiencing considerable stress. Blood was drawn and brain scans were given. Half the subjects were then taught formal mindfulness meditation at a residential retreat center; the rest completed a kind of sham mindfulness meditation that was focused on relaxation and distracting oneself from worries and stress. […]

At the end of three days, the participants all told the researchers that they felt refreshed and better able to withstand the stress of unemployment. Yet follow-up brain scans showed differences in only those who underwent mindfulness meditation. There was more activity, or communication, among the portions of their brains that process stress-related reactions and other areas related to focus and calm. Four months later, those who had practiced mindfulness showed much lower levels in their blood of a marker of unhealthy inflammation than the relaxation group, even though few were still meditating.

{ NY Times | Continue reading }

(The freckled face of Sweny, the druggist, appeals in the disc of the soapsun.)

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Marijuana is one of the most commonly used drugs in the United States, and use during adolescence — when the brain is still developing — has been proposed as a cause of poorer neurocognitive outcome. Nonetheless, research on this topic is scarce and often shows conflicting results, with some studies showing detrimental effects of marijuana use on cognitive functioning and others showing no significant long-term effects.

The purpose of the present study was to examine the associations of marijuana use with changes in intellectual performance in two longitudinal studies of adolescent twins (n = 789 and n = 2,277). We used a quasiexperimental approach to adjust for participants’ family background characteristics and genetic propensities, helping us to assess the causal nature of any potential associations. Standardized measures of intelligence were administered at ages 9–12 y, before marijuana involvement, and again at ages 17–20 y. Marijuana use was self-reported at the time of each cognitive assessment as well as during the intervening period.

Marijuana users had lower test scores relative to nonusers and showed a significant decline in crystallized intelligence between preadolescence and late adolescence. However, there was no evidence of a dose–response relationship between frequency of use and intelligence quotient (IQ) change. Furthermore, marijuana-using twins failed to show significantly greater IQ decline relative to their abstinent siblings.

Evidence from these two samples suggests that observed declines in measured IQ may not be a direct result of marijuana exposure but rather attributable to familial factors that underlie both marijuana initiation and low intellectual attainment.

{ Proceedings of the National Academy of Sciences }

photo { Julia Margaret Cameron, Paul and Virginia, 1864 }

‘The flame is not so bright to itself as to those on whom it shines: so too the wise man.’ —Nietzsche

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Starting at age 55, our hippocampus, a brain region critical to memory, shrinks 1 to 2 percent every year, to say nothing of the fact that one in nine people age 65 and older has Alzheimer’s disease. The number afflicted is expected to grow rapidly as the baby boom generation ages. Given these grim statistics, it’s no wonder that Americans are a captive market for anything, from supposed smart drugs and supplements to brain training, that promises to boost normal mental functioning or to stem its all-too-common decline. […]

A few years back, a joint study by BBC and Cambridge University neuroscientists put brain training to the test. Their question was this: Do brain gymnastics actually make you smarter, or do they just make you better at doing a specific task? […] All subjects took a benchmark cognitive test, a kind of modified I.Q. test, at the beginning and at the end of the study. Although improvements were observed in every cognitive task that was practiced, there was no evidence that brain training made people smarter.

There was, however a glimmer of hope for subjects age 60 and above. Unlike the younger participants, older subjects showed a significant improvement in verbal reasoning, one of the components of the benchmark test, after just six weeks of brain training, so the older subjects continued in a follow-up study for a full 12 months.

Results of this follow-up study, soon to be published in a peer-reviewed journal, generally show that continued brain training helps older subjects maintain the improvement in verbal reasoning seen in the earlier study. This is good news because it suggests that brain exercise might delay some of the effects of aging on the brain.

{ NY Times | Continue reading }

‘If youth were not ignorant and timid, civilization would be impossible.’ –Balzac

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In a stunning discovery that overturns decades of textbook teaching, researchers at the University of Virginia School of Medicine have determined that the brain is directly connected to the immune system by vessels previously thought not to exist. That such vessels could have escaped detection when the lymphatic system has been so thoroughly mapped throughout the body is surprising on its own, but the true significance of the discovery lies in the effects it could have on the study and treatment of neurological diseases ranging from autism to Alzheimer’s disease to multiple sclerosis.

{ EurekAlert | Continue reading }

unrelated { The benefits of a herpes infection }