28 January 2008

Neuron Signaling Networks:

Each neuron is a complex biomachine in its own right. Combined with its glial cell complement, a neuron forms a potent building block of more complex neural systems. Researchers at the UCSD School of Medicine and Moores UCSD Cancer Center are developing new technology for studying the signaling networks of neurons--how they grow neuritic extensions that form dendrites and axons.
This technological breakthrough opens the door to understanding how neurites form and differentiate to regenerate neuronal connections and give rise to a functioning network. It also led to the discovery of how two key signaling molecules are regulated by a complex protein network that controls neurite outgrowth. Their study will be published the week of January 28 to February 1 in the on-line, early edition of the journal Proceedings of the National Academy of Science.

The formation of neurites, a process called neuritogenesis, is the first step in the differentiation of neurons, the basic information cells of the central nervous system.... Neurons regenerate by sending out one or several long, thin neurites that will ultimately differentiate into axons, which primarily receive signals, or dendrites, primarily involved in sending out signals. These long, branch-like protrusions have a specialized sensory structure called a growth cone that probes the extracellular environment to find its way and determine which direction the neurite should move in order to hook up with other neurites that will also differentiate into axons and dendrites.

The neural signaling network of dendrites and axons forms a huge information grid, which the UCSD team is studying in order to discover how neurons connect properly and regenerate to maintain proper wiring of the brain. Understanding the role that neuritogenesis plays in the regeneration of nerve connections damaged by diseases such as Alzheimer’s, Parkinson’s or other neurogenerative diseases is an important component of mapping the signaling network.____Physorg

Neurons in different parts of the brain are specialised for different function--different parts of the genome are turned on and off according to a complex regulatory program. This genomic regulation controls the sophisticated cell-signaling pathway that controls what the cell machinery does--how the neuron connects to other neurons and glial cells in the larger system.

Our nervous systems are made of ultra-sophisticated building blocks. Each neuron is a processor in itself.

It is safe to say that neuroscientists do not understand how consciousness arises from the network of a hundred billion neurons in the human cortex. It is safe to say that artificial intelligence researchers likewise do not have a clue as to how consciousness can arise from neural networks.

The goals of ambitious machine intelligence researchers are laudable. The hopes of singularity enthusiasts and "friendly AI" advocates, are likewise admirable. Needless to say, the foundations of those hopes are less than solid. At this point, and for the foreseeable future, consciousness is the purview of biological nervous systems.

For over half a century, AI researchers have largely ignored the biological, embodied nature of the only consciousness the known universe has ever seen--biological consciousness. By ignoring the embodied nature of consciousness, AI has gone on several quite unproductive wild goose chases. Of course, like Edison with the electric light bulb, AI is learning thousands of ways that AI will not work.

That is not good enough. Researchers such as Jeff Hawkins may have finally started down a road of research that will lead to artificial modular systems that can display some limited aspects of "consciousness." It will be a multi-disciplinary task that will have to learn from neuroscience.

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Blogger Albin said...

nice blog
need to know more about it.

Tuesday, 29 January, 2008  

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