Friday, April 26, 2013

New Spin On Origins of Evolvability: Competition to Survive Not Necessary?

Scientists have long observed that species seem to have become increasingly capable of evolving in response to changes in the environment. But computer science researchers now say that the popular explanation of competition to survive in nature may not actually be necessary for evolvability to increase.   In a paper published this week inPLOS ONE, the researchers report that evolvability can increase over generations regardless of whether species are competing for food, habitat or other factors.  Using a simulated model they designed to mimic how organisms evolve, the researchers saw increasing evolvability even without competitive pressure.
Science Direct - Apr. 26, 2013

Joel Lehman, Kenneth O. Stanley.
Evolvability Is Inevitable: Increasing Evolvability without the Pressure to Adapt. 
PLoS ONE, 2013; 8 (4): e62186 DOI: 10.1371/journal.pone.0062186

Sunday, April 21, 2013

Stem Cell Transplant Restores Memory, Learning in Mice

 For the first time, human embryonic stem cells have been transformed into nerve cells that helped mice regain the ability to learn and remember.
A study at the University of Wisconsin-Madison is the first to show that human stem cells can successfully implant themselves in the brain and then heal neurological deficits, says senior author Su-Chun Zhang, a professor of neuroscience and neurology.  Once inside the mouse brain, the implanted stem cells formed two common, vital types of neurons, which communicate with the chemicals GABA or acetylcholine. "These two neuron types are involved in many kinds of human behavior, emotions, learning, memory, addiction and many other psychiatric issues," says Zhang.

Yan Liu, et al.
Medial ganglionic eminence–like cells derived from human embryonic stem cells correct learning and memory deficits. Nature Biotechnology, 2013; DOI:10.1038/nbt.2565

Monday, April 15, 2013

Brain Development Is Guided by Junk DNA That Isn't Really Junk

 Specific DNA once dismissed as junk plays an important role in brain development and might be involved in several devastating neurological diseases, UC San Francisco scientists have found.
Their discovery in mice is likely to further fuel a recent scramble by researchers to identify roles for long-neglected bits of DNA within the genomes of mice and humans alike. While researchers have been busy exploring the roles of proteins encoded by the genes identified in various genome projects, most DNA is not in genes. This so-called junk DNA has largely been pushed aside and neglected in the wake of genomic gene discoveries, the UCSF scientists said. In their own research, the UCSF team studies molecules called long noncoding RNA (lncRNA, often pronounced as "link" RNA), which are made from DNA templates in the same way as RNA from genes.
Science Daily, Apr. 15, 2013

Alexander D. Ramos, et al.
Integration of Genome-wide Approaches Identifies lncRNAs of Adult Neural Stem Cells and Their Progeny In Vivo.
Cell Stem Cell, 2013 DOI:10.1016/j.stem.2013.03.003

Friday, April 12, 2013

Deep Homology of Arthropod Central Complex and Vertebrate Basal Ganglia

Similarities of brain structure, function, and behavior are usually ascribed to convergent evolution. In their review, Strausfeld and Hirth (p. 157) identify multiple commonalities shared by vertebrate basal ganglia and a system of forebrain centers in arthropods called the central complex. The authors conclude that circuits essential to behavioral choice originated very early across phyla.

Nicholas J. Strausfeld, et al
Science 12 April 2013:
Vol. 340 no. 6129 pp. 157-161 , DOI: 10.1126/science.1231828

Thursday, April 11, 2013

See-through brains clarify connections

A chemical treatment that turns whole organs transparent offers a big boost to the field of ‘connectomics’ — the push to map the brain’s fiendishly complicated wiring. Scientists could use the technique to view large networks of neurons with unprecedented ease and accuracy. The technology also opens up new research avenues for old brains that were saved from patients and healthy donors.

Helen Shen
Nature 496, 151 (11 April 2013) doi:10.1038/496151a

Kwanghun Chung, et al
Structural and molecular interrogation of intact biological systems
Nature (2013) doi:10.1038/nature12107

Thursday, April 4, 2013

A 'Light Switch' in Brain Illuminates Neural Networks

 There are cells in your brain that recognize very specific places, and have that as one of their main jobs. These cells, called place cells, are found in an area behind your temple called the hippocampus. While these cells must be sent information from nearby cells to do their job, so far no one has been able to determine exactly what kind of nerve cells, or neurons, work with place cells to craft the code they create for each location. Neurons come in many different types with specialized functions. Some respond to edges and borders, others to specific locations, others act like a compass and react to which way you turn your head.
Science News Apr. 4, 2013 

Sheng-Jia Zhang*,†, Jing Ye*, Chenglin Miao, Albert Tsao, Ignas Cerniauskas, Debora Ledergerber, May-Britt Moser, Edvard I. Moser. Optogenetic Dissection of Entorhinal-Hippocampal Functional ConnectivityScience, 5 April 2013: Vol. 340 no. 6128 DOI: 10.1126/science.1232627