During gestation, the fetal brain develops dramatically as structures and connections form, providing the foundation for all future development. The fetal environment plays a critical role in these early neural processes, for better or for worse. Scientists now know that exposure to maternal stress can sometimes have deleterious effects on the fetus, depending on the cause, timing, duration, and intensity of stress. Fortunately, postnatal interventions, such as a secure parent-infant bond and an enriched environment, can buffer the potential negative consequences.

The gestational environment can impact fetal brain structure and function and increase long-term susceptibility to neurodevelopmental and neuropsychiatric disorders (see Figure 1).^1-3 This can occur independently or in conjunction with genetic or postnatal factors. For several reasons, environmental influences during fetal development are especially potent in the brain. First, gestation is when differentiation of major brain structures occurs, thus creating greater sensitivity to environmental conditions than at other times during the life span. Second, brain development involves a cascade of interactions with the environment, so that even small deviations from the normal developmental trajectory during fetal life can become progressively magnified over time, producing long-lasting or permanent consequences. And third, the immature fetal blood-brain barrier offers limited protection against neurological insults.⁴ For these reasons, the brain’s plasticity during gestation confers both increased vulnerability to environmental exposures and opportunities for therapeutic interventions.

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“Considering the fundamental importance of fluid intelligence in everyday life and its predictive power for a large variety of intellectual tasks and professional success, we believe that our findings may be highly relevant to applications in education,” U-M psychology researchers Susanne Jaeggi and Martin Buschkuehl concluded.

Many psychologists believe general intelligence can be separated into “fluid” and “crystalline” components. Fluid intelligence—considered one of the most important factors in learning—applies to all problems while crystallized intelligence consists of skills useful for specific tasks.

“Working memory and fluid intelligence both seem to rely on similar neural networks,” Jaeggi said. “Our study does not permit us to know how long the training-gain persists. Longitudinal studies will be required to address that issue.”

Previously, many psychologists believed the only way to increase fluid intelligence was through direct practice of the tests themselves, rather than by training. But the new findings show that multiple efforts designed to improve memory skills similarly improve fluid intelligence.

After initially giving subjects a standard test for fluid intelligence, the researchers gave subjects a series of training exercises designed to improve their working memory.

The training was given to four groups, who repeated the exercises for eight, 12, 17, or 19 days. After the training, the researchers re-tested the subjects’ fluid intelligence.

Although the performance of untrained controls improved slightly, the trained subjects showed a significant performance improvement, which increased with time spent training.

“The more training, the more improvement in fluid intelligence,” Jaeggi said.

The researchers suggest that the training exercises strengthened multiple “executive processes” in the brain that function in problem-solving, noting that fluid intelligence is usually seen as “robust against influences of education and socialization, and it is commonly seen as having a strong hereditary component.”

The research is detailed in a recent  article in the Proceedings of the National Academy of Sciences (PNAS).

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ScienceDaily (Apr. 10, 2012) — Scientists report that they have mapped the physical architecture of intelligence in the brain. Theirs is one of the largest and most comprehensive analyses so far of the brain structures vital to general intelligence and to specific aspects of intellectual functioning, such as verbal comprehension and working memory.

Their study, published in Brain: A Journal of Neurology, is unique in that it enlisted an extraordinary pool of volunteer participants: 182 Vietnam veterans with highly localized brain damage from penetrating head injuries.

“It’s a significant challenge to find patients (for research) who have brain damage, and even further, it’s very hard to find patients who have focal brain damage,” said University of Illinois neuroscience professor Aron Barbey, who led the study. Brain damage — from stroke, for example — often impairs multiple brain areas, he said, complicating the task of identifying the cognitive contributions of specific brain structures.

But the very focal brain injuries analyzed in the study allowed the researchers “to draw inferences about how specific brain structures are necessary for performance,” Barbey said. “By studying how damage to particular brain regions produces specific forms of cognitive impairment, we can map the architecture of the mind, identifying brain structures that are critically important for specific intellectual abilities.”

The researchers took CT scans of the participants’ brains and administered an extensive battery of cognitive tests. They pooled the CT data to produce a collective map of the cortex, which they divided into more than 3,000 three-dimensional units called voxels. By analyzing multiple patients with damage to a particular voxel or cluster of voxels and comparing their cognitive abilities with those of patients in whom the same structures were intact, the researchers were able to identify brain regions essential to specific cognitive functions, and those structures that contribute significantly to intelligence.

“We found that general intelligence depends on a remarkably circumscribed neural system,” Barbey said. “Several brain regions, and the connections between them, were most important for general intelligence.”

These structures are located primarily within the left prefrontal cortex (behind the forehead), left temporal cortex (behind the ear) and left parietal cortex (at the top rear of the head) and in “white matter association tracts” that connect them.

The researchers also found that brain regions for planning, self-control and other aspects of executive function overlap to a significant extent with regions vital to general intelligence.

The study provides new evidence that intelligence relies not on one brain region or even the brain as a whole, Barbey said, but involves specific brain areas working together in a coordinated fashion.

“In fact, the particular regions and connections we found support an emerging body of neuroscience evidence indicating that intelligence depends on the brain’s ability to integrate information from verbal, visual, spatial and executive processes,” he said.

The findings will “open the door to further investigations into the biological basis of intelligence, exploring how the brain, genes, nutrition and the environment together interact to shape the development and continued evolution of the remarkable intellectual abilities that make us human,” Barbey said.

The research team also included scientists from Universidad Autónoma de Madrid; Medical Numerics, in Germantown, Md.; George Mason University; the University of Delaware; and the Kessler Foundation, in West Orange, N.J.

The U.S. National Institute of Neurological Disorders and Stroke at the National Institutes of Health provided funding for this research.

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