Issue 96 / November - December 2013
Mini "human brain" in a dish
Cerebral organoids model human brain development and microcephaly
Lancaster et al. Nature, September 2013
A recent study reported the first living model of the developing human brain in a lab dish. Scientists first grew induced pluripotent stem cells (iPSCs) in conditions that allowed them to form a precursor brain tissue called neuroectoderm. Then, they embedded fragments of the neuroectoderm in droplets of gel to create a 3D scaffold to guide further growth. Next, they transferred theses droplets to a spinning vessel that increased nutrient absorption. In two to three weeks, "minibrains" called cerebral organoids emerged out of this tissue, each enclosing a fluid-filled region, much like the cerebral ventricles that contain cerebrospinal fluid in the human brain. After another one to two weeks, defined brain areas were formed out of some of the organoids, including a cerebral cortex (the brain's complex outer layer); retinal tissue, the light-sensitive part of the eye; meninges, the membranes that envelope the brain; and choroid plexus, which produces the cerebrospinal fluid that bathes the brain. The minibrains could last for at least 10 months in culture and could only grow about 2 to 3 millimeters in diameter, as they lack a circulatory system to provide sufficient nutrients and oxygen to their core regions. Minibrains not only help scientists to explore how a healthy human brain develops but also to study microcephaly, a human genetic disorder in which brain size is dramatically reduced. The researchers found that minibrains cultured from iPSCs derived from the skin of a patient with microcephaly did not grow as big as clumps grown from iPSCs derived from a healthy person. Remarkably, these small chunks contained more neurons than expected. With further analyses, researchers found that brains of microcephaly patients develop neurons too early, basically well before their brains have grown large enough. The human "minibrain" model opens the door for many studies which will include the more common neurological disorders such as autism and schizophrenia.
An unusual Mars rock
The Petrochemistry of Jake_M: A Martian Mugearite
Stolper et al. Science, September 2013.
For the last fourteen months, the Mars Science Laboratory (MSL) rover, Curiosity, has been scooping soil, drilling rocks, and analyzing samples by using the most sophisticated set of scientific instruments to explore fundamental physical and chemical properties of the terrestrial planet Mars. A team of MSL scientists recently reported that an Earth-like martian rock they discovered could provide new insights into the history of Mars's interior. A few weeks after it landed, Curiosity encountered a 50-centimeter-tall pyramid-shaped rock across Gale Crater. This dark gray rock was named "Jake_M" after one of the MSL engineers, Jacob "Jake" Matijevic, who passed away two weeks after Curiosity's landing. Jake_M is basaltic igneous rock that is chemically similar to "mugearites" typically found in ocean islands and continental rifts on Earth. Mugearites are formed through a crystallization process in the presence of 1-2 percent water in magma deep within Earth. In addition, the discovery of Jake_M implies that the interior of Mars is composed of areas with mixed chemical compositions. Perhaps Mars never became homogenized, the way Earth has, through its plate tectonics and convection processes. Scientists suggests that these findings provide an evidence for water deep beneath the surface of Mars, and they add to the growing body of studies pointing to the presence of water on the Red Planet ÔÇô an ingredient necessary for life.
It's grandparents' turn to play!
Video game training enhances cognitive control in older adults.
Anguera et al. Nature, September 2013.
Video games are perceived as a meaningless way to waste time for many people; however, a growing body of evidence suggests that creatively designed games can dramatically improve brain power. Scientists from University of California, San Francisco, designed a 3D video game to enhance older adults' cognitive capacities. The task of this game, named NeuroRacer, is to navigate a race car around a winding track, while keeping an eye out for specific road signs. As road signs appear, players are asked to press a button. NeuroRacer basically requires players to rapidly switch between tasks without losing attention and focus. After 12 hours of playing, healthy people ages 60 to 79 performed as well as people in their 20s. The cognitive improvements acquired through game play were not temporary, as they were still evident six months later. The researchers also monitored the brain waves of older participants using electroencephalography. They found that there were increases in a brain wave called theta, a low-level frequency associated with attention. Moreover, the participants showed significant improvements in sustained attention and working memory, which are beyond the skills learned for the game. Of course this does not mean that any video game would have the same effect on the mental abilities. For games to be beneficial, they should be designed with a specific goal in mind, meet certain criteria and be proven effective through rigorous scientific research. Such games could also help people of any age suffering from attention deficit hyperactivity disorder (ADHD), dementia, brain injury, stroke, chemical addiction, and many other neurological conditions. Future versions of the games are planned for tablets and smartphones, to make the training accessible to more people.