Eddy,

Read the article I provided a link to in the first post on this thread. This is not my interpretation.

Here is a direct quote form the link at http://www.sciencedaily.com/releases...1127123927.htm:

<An MIT research team's latest finding suggests that stem cell therapies for the brain could be much more complicated than previously thought.

MIT scientists report that adult stem cells produced in the brain are pre-programmed to make only certain kinds of connections- - making it impossible for a neural stem cell originating in the brain to be transplanted to the spinal cord, for instance, to take over functions for damaged cells.

Some researchers hope to use adult stem cells produced in the brain to replace neurons lost to damage and diseases such as Alzheimer's. The new study calls this into question.

"It is wishful thinking to hope that adult stem cells will be able to modify themselves so that they can become other types of neurons lost to injury or disease," said Carlos E. Lois, assistant professor of neuroscience in MIT's Picower Institute for Leaning and Memory.>

Another article references stem cells for neural cell rescue: http://www.sciencedaily.com/releases...0201171754.htm

The pertinent quote is <The new report, co-authored by several international research groups and led by Karolinska Institutet, shows that stem cells transplanted into damaged or threatened nerve tissue quickly establish direct channels, called gap junctions, to the nerve cells. Stem cells actively bring diseased neurons back from the brink via cross-talk through gap junctions, the connections between cells that allow molecular signals to pass back and forth. The study found that the nerve cells were prevented from dying only when these gap junctions were formed. The results were obtained from mice and human stem cells in cultivated brain tissue, and from a series of rodent models for human neurodegenerative diseases and acute brain injuries.>

The report about 5000 different neuronal cell classes is available online at: http://www.researchchannel.org/prog/...=29385&fID=679

It is a 58 minute lecture with graphic demonstrations and live video presentations of microscopic events. You can actually see the brain cells make connections. Well worth the time. The lecturer is very good at presenting information. The part about 5000 cell classes is about 5 to 10 minutes in.

The summary quote tells the basic point
<Thomas M. Jessel, Howard Hughes Medical Institute Investigator, explores the human brain, the sophisticated product of 500 million years of vertebrate evolution, assembled during just nine months of embryonic development. The functions encoded by its trillion nerve cells direct all human behavior. Yet the brain is a biological organ made from the same building blocks as skin, liver and lung. How does the brain acquire its remarkable computational power? Answers lie in the details of its construction -- the cellular and molecular mechanisms that drive the formation of thousands of neural circuits, each wired for a specific behavior. >

So, you can do further research on these and other web sites **

If you think I have mis-stated anything, PM me or post here openly. I am not afraid of criticism. Wisdom is gained by learning from errors, not denying them.