IQ Inherited, Suggests Twin Study

Genes have a very strong influence over how certain parts of our brains develop, scientists in the US and Finland have found. And the parts most influenced are those that govern our cognitive ability. In short, you inherit your IQ.

Paul Thompson at the University of California at Los Angeles and his colleagues used MRI to scan the brains of 10 pairs of identical and 10 pairs of fraternal twins. Identical twins have identical genes, whereas fraternal twins sharing on average half their genes. The twins shared environments, means researchers can separate genetic and environmental factors.

The researchers found that certain regions of the brain were highly heritable. These included language areas, known as Broca's and Wernicke's areas, and the frontal region, which, among other things, plays a huge role in cognition.

In identical twins, these areas showed a 95 to 100 per cent correlation between one twin and the other - they were essentially the same. The frontal structure, says Thompson, appears to be as highly influenced by genes as the most highly influenced trait we know of - fingerprints.

"It's extraordinary how similar they are," he says. The finding suggests that environment - their experiences, what they learned in life, who they knew - played a negligible role in shaping it.

Fraternal twins were near-identical in Wernicke's area, but less similar in other areas, with about 60 to 70 per cent correlation. Random pairs of people would be expected to have no correlation.

The study was all the more interesting in that it found that not only was this gray matter highly heritable, but it affected overall intelligence as well. "We found that differences in frontal gray matter were significantly linked with differences in intellectual function," the authors write.

The volunteers each took a battery of tests that examined 17 separate abilities, including verbal and spatial working memory, attention tasks, verbal knowledge, motor speed and visuospatial ability.

These tests hone in on what's known as "g", the common element measured by IQ tests. People who do well on one of these tests tend to do well on them all, says Thompson.

It is not known what exactly "g" is. But these new findings suggest that "g" is not just a statistical abstraction, but rather, that it has a biological substrate in the brain, says Robert Plomin, of the Institute of Psychiatry in London. Plomin has spent eight years looking for genes behind "g". "I'm convinced that there are genes," he says, a lot of them, each with a small effect.

Stephen Kosslyn of Harvard University in Boston questions whether "g" should really be called intelligence. "G" picks up on abilities such as being able to abstract rules or figure out how to order things according to rules. "It's the kind of intelligence you need to do well in school," he says. "Not what you need to do well in life."

Source: University Of California - Los Angeles (http://www.ucsd.edu/)

Date: Posted 11/5/2001

UCLA Team Maps How Genes Affect Brain Structure, Intelligence; Dramatic Images Shed Light On Brain Diseases, Personality Differences

UCLA brain mapping researchers have created the first images to show how an individual’s genes influence their brain structure and intelligence.
The findings, published in the Nov. 5 issue of the journal Nature Neuroscience, offer exciting new insight about how parents pass on personality traits and cognitive abilities, and how brain diseases run in families.

The team found that the amount of gray matter in the frontal parts of the brain is determined by the genetic make-up of an individual’s parents, and strongly correlates with that individual’s cognitive ability, as measured by intelligence test scores.

More importantly, these are the first images to uncover how normal genetic differences influence brain structure and intelligence.

Brain regions controlling language and reading skills were virtually identical in identical twins, who share exactly the same genes, while siblings showed only 60 percent of the normal brain differences.

This tight structural similarity in the brains of family members helps explain why brain diseases, including schizophrenia and some types of dementia, run in families.

“We were stunned to see that the amount of gray matter in frontal brain regions was strongly inherited, and also predicted an individual’s IQ score,” said Paul Thompson, the study’s chief investigator and an assistant professor of neurology at the UCLA Laboratory of Neuro Imaging.

“The brain’s language areas were also extremely similar in family members. Brain regions that were found to be most similar in family members may be especially vulnerable to diseases that run in families, including some forms of psychosis and dementia.”

The scientists employed magnetic resonance imaging technology to scan a group of 20 identical twins, whose genes are identical, and 20 same-sex fraternal twins, who share half their genes.

Using a high-speed supercomputer, they created color-coded images showing which parts of the brain are determined by our genetic make-up, and which are more adaptable to environmental factors, such as learning and stress.

To create the maps of genetic influences on the brain, the UCLA scientists teamed up with the National Public Health Institute of Finland, and the Finnish Universities of Helsinki and Oulu.

In a national initiative, the Finnish team tracked all the same-sex twins born in Finland between 1940 and 1957 — 9,500 pairs of twins — many of whom received brain scans and cognitive tests.

Their genetic similarity was confirmed by analyzing 78 different genetic markers. These individual pieces of DNA match exactly in identical twins, and half of them match in siblings.

Recent research has shown that many cognitive skills are surprisingly heritable, with strong genetic influences on verbal and spatial abilities, reaction times, and even some personality qualities, including emotional reactions to stress.

These genetic relationships persist even after statistical adjustments are made for shared family environments, which tend to make members of the same family more similar. Until this study, little was known about how much individual genotype accounts for the wide variations among individual brains, as well as individual’s cognitive ability.

The UCLA researchers are also applying this new genetic brain mapping approach to relatives of schizophrenic patients, and individuals at genetic risk for Alzheimer’s disease, to screen them for early brain changes, and help understand familial risk for inherited brain disorders where specific risk genes are unknown.

Other UCLA researchers involved in the project are Tyrone Cannon, a professor of psychiatry and biobehavioral and human genetics, and Arthur Toga, professor of neurology and director of the UCLA Laboratory of Neuro Imaging.

Images from the study are available online for viewing or downloading at http://www.loni.ucla.edu/~thompson/MEDIA/NN/IMAGES/

THE GENIUS GENE

Researchers uncover the secret to memory and learning in mice. Does it have the same effect in humans?

Most mice have lousy short-term memories. Put them in a cage with objects they saw just yesterday and the mice will inspect the blocks or toys as if they are brand new. But in a lab at Princeton University, Joe Tsien tests some mice the are a bit more like elephants—even five days after seeing an object for the first time, these non-descript brown mice remember it well enough to ignore as neither food nor foe.

Tsien's mice are not natural talents. They have been genetically engineered to be smarter. By adding a just single gene, researchers greatly enhanced the mouse's learning ability and memory. The gene codes for a communication channel in the brain that seems to be the master key to the brain's gateway for memories and learning experiences.

For the past years, it has been the declared goal of Tsien's lab to find the cellular and molecular mechanisms of how memories are stored in the brain. The researchers knew from previous research that a sub-unit of the communication channel played a role in the ability of brain cells to interact. Presumably, interconnections form as memories are stored in the brain, a flexibility that is typical for juvenile brains.

To test the role of the receptor, called NMDA, Tsien and co-workers engineered mice that lacked the gene that codes for that sub-unit. The resulting mice were rather stupid, incapable of remembering a platform submerged in murky water even after a short time, although it was always in the same place. But researchers couldn't prove the channel actually made mice smarter until they reversed the experiment.

The new results, published in the September 3 issue of Nature, obliterates any remaining doubt that the receptor is one of the key switches in the mechanism of memory and learning, says Tsien. The receptor is located strategically at the synapse, the spot where two brain cells meet and communicate. It works like a door: a signal molecule rings the bell and the receptor opens up to let in messengers—electrically-charged calcium atoms in this case. The calcium initiates an electrical pulse that relays the message to other synapses at the opposite end of the brain cell.

In the transgenic mice, the genetically modified sub-unit keeps the door open longer and lets in more messengers to make sure the message does not get lost on the way. And the effect does not wear off over time, so the mice are both unusually smart and retain an elastic juvenile memory. This inspired the researchers to name them "Doogie", after the precocious TV doctor in "Doogie Howser, M.D."

The "Doogie" mice performed better than normal mice in a range of behavioral experiments. They remembered familiar objects up to five times longer than normal mice. They also remembered receiving a weak electrical shock longer, and learned faster to associate it with a sound. Tsien believes this is an important finding: in both mice and men, memories of places or objects and memories of emotions, such as pain, are stored in different parts of the brain. "The mechanisms underlying emotional and rational learning may be the same. We see that (in mice) this receptor affects both," says Tsien.

The receptor also exists in humans, and it is possible that it plays the same role. If so, pharmaceutical companies may some day find a small molecule they can pack into a pill that can modify the channel's properties—or even the activity of the gene itself. Advances in gene therapy technology may make it possible to deliver the chunk of gene directly to the part of the brain affected by memory loss. The most controversial option may be the manipulation of embryos to create genetically-modified geniuses. "We have to be extremely careful to be starting this kind of adventure," Tsien says. In any case, an actual therapy for people's mental abilities is far off. "It's not like tomorrow you're gonna have something," he says.

But Tsien adds, "The question isn't whether we can do it, but it's whether and when we should do it."

What is intelligence, anyway?

Intelligence: How Well Data In Environment Is Used

What is intelligence? This may seem to be more of a question for psychologists than physicists. But two physics researchers argue that intelligence is not an abstract concept, but must be considered as a physical phenomenon.
The researchers are Joseph Wakeling, now at the University of Fribourg, Switzerland, and Per Bak of Imperial College of London.
Any definition of intelligence, they say, cannot ignore a living being's environment, including its very own body. In their view, an organism is only intelligent relative to how well it solves the problems that its surroundings throw at it.
This runs counter to many historical ideas, including the concept that the mind is separate from the body, or that it is possible to build a desktop computer that thinks like a human without having the same physical environment or body.
To explore the idea of intelligence, the researchers ran computer simulations of artificial neural networks called "minibrains." In the simulations, 251 minibrains each attempted to pick the less popular of two choices, 0 and 1, analogous to 251 motorists all trying to pick the less congested road. This "Minority Game" would be repeated over many successive rounds.
Each minibrain consisted of three layers of "neurons": "input neurons," which dictated how many past rounds it could remember, leading to an intermediary layer, which then led into an "output" layer that determined what choice was made.
If the minibrain ended up making an incorrect choice, it would reduce the strength of the connections between neurons supplying the "wrong answer."
The researchers were in for a surprise when they endowed all of the minibrains with equal abilities, which would be analogous to a bunch of motorists with the same amount of decision-making skill. In this situation, no minibrains correctly guessed the minority choice with even a 50 percent success rate, which is what you'd get by making the choice with a random flip of a coin.

Even an E. coli bacterium, which searches for glucose by moving in random directions in its environment, is seemingly more intelligent than this.
Only when the researchers introduced a "rogue" minibrain with more intermediate neurons to analyze the past rounds did it attain more than a 50 percent success rate. Their simulations suggest that intelligence often hinges on how much one can make use of the data in one's physical environment. (Wakeling and Bak, Physical Review E, November 2001

Can brain lobes be transplanted?

Smarter than the average E. coli bacterium.

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