The embryonic origins of human consciousness may come from a stem cell newly-identified in mice, say scientistsfrom The Scripps Research Institute in La Jolla.
Brain cells that form the upper layers of the cerebral cortex, where higher brain functions are located, arise from this stem cell, the scientists say.
A paper on the research was published in the Aug. 10 issue of the journal Science.
While the study was performed in mice, the same kinds of cells are found in humans and other mammals. In humans, defects in the function of the upper cortical layers result in such disorders as schizophrenia and autism, the paper stated.
These stem cells constitute a subset of what are calledradial glial cells, or RGC cells, which form various layers of the cortex. The cells in this subset, regardless of when they are formed in the developing brain, produce the upper layers of the cortex.
The upper cortical layers are a "relatively young invention" in evolutionary history, said Ulrich Mueller, a Scripps Research professor and senior author of the paper, in a Scripps press release. The paper's first author was Santos Franco, a senior research associate in Mueller's laboratory.
"Because upper cortical layers were expanded during primate evolution, amplification of this RGC pool may have facilitated human brain evolution," the paper stated.
"But, bigger brains came with a risk, making humans more prone to disorders when upper-layer neurons don't form connections properly," stated the Scripps press release. "Up until now, researchers trying to reproduce human cortical neurons in the lab from stem cells have only generated lower-layer-type neurons."
"This opens a door now to try to make the upper-layer neurons, which are frequently affected in psychiatric disorders," Mueller said.
The research was supported by the Dorris Neuroscience Center at the Scripps Research Institute, the U.S. National Institutes of Health, and the California Institute for Regenerative Medicine.
Call staff writer Bradley J. Fikes at 760-739-6641.
