News tagged with brain size
(Medical Xpress) -- When it comes to intelligence, what factors distinguish the brains of exceptionally smart humans from those of average humans?
Neuroscience Aug 01, 2012 | 4.6 / 5 (22) | 6 |
(Medical Xpress) -- Researchers at Duke University Medical Center have found an apparent correlation between religious practices and changes in the brains of older adults.
Neuroscience May 19, 2011 | 4.3 / 5 (8) | 129 |
(Medical Xpress)—The instability of "white matter" in humans may contribute to greater cognitive decline during the aging of humans compared with chimpanzees, scientists from Yerkes National Primate Research ...
Neuroscience May 14, 2013 | 5 / 5 (4) | 2 |
Is athleticism linked to brain size? Research on mice shows that exercise-loving mice have larger midbrains
Is athleticism linked to brain size? To find out, researchers at the University of California, Riverside performed laboratory experiments on house mice and found that mice that have been bred for dozens of ...
Medical research Jan 17, 2013 | 5 / 5 (1) | 0 |
(Medical Xpress)—Neurobiologists at the Research institute of Molecular Pathology (IMP) in Vienna have discovered one of the key genes required to make a brain. Mutations in this gene, called TUBB5, cause ...
Genetics Dec 14, 2012 | 5 / 5 (2) | 0 |
(HealthDay)—Newborns who weigh around 9 pounds or more at birth tend to have bigger brains as teens than those who weigh less at birth, a new study finds.
Health Nov 19, 2012 | 4 / 5 (4) | 1 |
Research published Aug. 1 by scientists at Cold Spring Harbor Laboratory (CSHL) links gene mutations found in some patients with Meier-Gorlin syndrome (MGS) with specific cellular dysfunctions that are thought to give rise ...
Genetics Jul 31, 2012 | not rated yet | 0 |
A research team led by Seattle Children's Research Institute has discovered new gene mutations associated with markedly enlarged brain size, or megalencephaly. Mutations in three genes, AKT3, PIK3R2 and PIK3CA, were also ...
Genetics Jun 29, 2012 | 4.7 / 5 (3) | 0 |
Scientists at the Ottawa Hospital Research Institute (OHRI) and the University of Ottawa (uOttawa) have discovered that mice that lack a gene called Snf2l have brains that are 35 per cent larger than normal. ...
Genetics May 15, 2012 | 3.5 / 5 (4) | 0 |
Scientists have discovered a mutation limited to brain tissue that causes hemimegalencephaly (HMG), a condition where one half of the brain is enlarged and dysfunctional, leading to intellectual disability and severe epilepsy. ...
Neuroscience Apr 11, 2012 | 5 / 5 (1) | 0 |
(Medical Xpress) -- Researchers are suggesting that there is a link between the number of friends you have and the size of the region of the brain known as the orbital prefrontal cortex that ...
Neuroscience Feb 02, 2012 | 3 / 5 (11) | 10 |
Brain tissue is a major consumer of energy in the body. If an animal species evolves a larger brain than its ancestors, the increased need for energy can be met by either obtaining additional sources of food or by a trade-off ...
Neuroscience Nov 09, 2011 | 5 / 5 (1) | 0 |
New research suggests the growth rate of the brain's cerebral cortex in babies born prematurely may predict how well they are able to think, speak, plan and pay attention later in childhood. The research is published in the ...
Neuroscience Oct 12, 2011 | 4.3 / 5 (3) | 0 |
(Medical Xpress) -- Imagine shrinking to the size of a doll in your sleep. When you wake up, will you perceive yourself as tiny or the world as being populated by giants? Researchers at Karolinska Institutet ...
Psychology & Psychiatry May 25, 2011 | 4 / 5 (1) | 6 |
Scientists using magnetic resonance imaging (MRI) observed that the brains of children with autism spectrum disorder are larger than those without autism, but this difference appears related to increased rates ...
Psychology & Psychiatry May 02, 2011 | 4.5 / 5 (4) | 0 |
There has been quite a bit of study of the relationships between brain size, body size, and other variables across a wide range of species, largely because the easiest way to study any object is to measure its size. Even for extinct species brain size can be estimated by measuring the cavity inside the skull. The story that emerges, however, is complex.
As might be expected, brain size tends to increase with body size (measured by weight, which is roughly equivalent to volume). The relationship is not a strict proportionality, though: averaging across all orders of mammals, it follows a power law, with an exponent of about 0.75. There are good reasons for expecting a power law: for example, the body-size-to-body-length relationship follows a power law with an exponent of 0.33, and the body-size-to-surface-area relationship a power law with an exponent of 0.67. The explanation for an exponent of 0.75 is not obvious—however it is worth noting that several physiological variables appear to be related to body size by approximately the same exponent, for example, the basal metabolic rate. This power law formula applies to the "average" brain of mammals taken as a whole, but each family (cats, rodents, primates, etc) departs from it to some degree, in a way that generally reflects the overall "sophistication" of behavior. Primates, for a given body size, have brains 5 to 10 times as large as the formula predicts. Predators tend to have relatively larger brains than the animals they prey on; placental mammals (the great majority) have relatively larger brains than marsupials such as the opossum.
When the mammalian brain increases in size, not all parts increase at the same rate. In particular, the larger the brain of a species, the greater the fraction taken up by the cortex. Thus, in the species with the largest brains, most of their volume is filled with cortex: this applies not only to humans, but also to animals such as dolphins, whales, or elephants.
The evolution of homo sapiens over the past two million years has been marked by a steady increase in brain size, but much of it can be accounted for by corresponding increases in body size. There are, however, many departures from the trend that are difficult to explain in a systematic way: in particular, the appearance of modern man about 100,000 years ago was marked by a decrease in body size at the same time as an increase in brain size. Even so, it is notorious that Neanderthals, which went extinct about 40,000 years ago, had larger brains than modern homo sapiens.
Not all investigators are happy with the amount of attention that has been paid to brain size. Roth and Dicke, for example, have argued that factors other than size are more highly correlated with intelligence, such as the number of cortical neurons and the speed of their connections. Moreover they point out that intelligence depends not just on the amount of brain tissue, but on the details of how it is structured.
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This text uses material from Wikipedia and is available under the GNU Free Documentation License.