Brain complexity: essay on the complexity (Introduction)

by David Turell , Tuesday, March 22, 2016, 18:40 (3168 days ago) @ David Turell

A reviews of how complex are the neurons themselves and their enormous connectivity:-http://blogs.scientificamerican.com/cross-check/the-singularity-and-the-neural-code/?WT.mc_id=SA_DD_20160322-"Specialists in real rather than artificial brains find these scenarios laughably naïve, because we are still so far from understanding how brains make minds. “No one has the foggiest notion,” says Nobel laureate Eric Kandel. “At the moment all you can get are informed, intelligent opinions.” Neuroscientists lack an overarching, unifying theory to make sense of their sprawling and disjointed findings, such as Kandel's discovery of the chemical and genetic processes that underpin memory formation--in sea slugs.-"The brain is with good reason often called the most complex phenomenon known to science. A typical adult brain contains about 100 billion nerve cells, or neurons. A single neuron can be linked via axons (output wires) and dendrites (input wires) across synapses (gaps between axons and dendrites) to as many as 100 000 other neurons. Crank the numbers and you find that a typical human brain has quadrillions of connections among its neurons.-"Adding to the complexity, synaptic connections constantly form, strengthen, weaken, dissolve. Old neurons die and—a growing body of evidence indicates, overturning decades of dogma--new ones are born throughout our lives. Cells can also be retrained for different jobs, switching from facial expressions to finger flexing, or from seeing red to hearing squeaks.-"Far from being stamped from a common mold, neurons display an astounding variety of forms and functions. Researchers have discovered scores of distinct types just in the optical system. Neurotransmitters, which carry signals across the synapse between two neurons, also come in many different varieties. Other chemicals, such as neural-growth factors and hormones, also ebb and flow through the brain, modulating cognition in manners subtle and profound.-***-"The neural code is science's deepest, most consequential problem. If researchers crack the code, they might solve such ancient philosophical conundrums as the mind-body problem and the riddle of free will. A solution to the neural code could also, in principle, give us unlimited power over our brains and hence minds. Science fiction—including mind-control, mind-reading, bionic enhancement and even psychic uploading—could become reality.-"But the most profound problem in science is also by far the hardest. Neuroscientists still have no idea what the neural code is. That is not to say they don't have any candidates. Far from it. Like voters in a U.S. presidential primary, researchers have a surfeit of candidates, each seriously flawed.-***-"Koch doubts, however, that the neural code “will be anything as simple and as universal as the genetic code.” Neural codes seem to vary in different species, he notes, and even in different sensory modes within the same species. “The code for hearing is not the same as that for smelling,” he explains, ”in part because the phonemes that make up words change within a tiny fraction of a second, while smells wax and wane much more slowly.”-“'There may be no universal principle” governing neural-information processing, Koch says, “above and beyond the insight that brains are amazingly adaptive and can extract every bit of information possible, inventing new codes as necessary.” So little is known about how the brain processes information that “it's difficult to rule out any coding scheme at this time.”-***-"Together with eminent neurosurgeon Itzhak Fried, Koch has identified neurons that respond to images of specific people, from Bill Clinton to Sylvester Stallone. The neurons were discovered in epileptics in whom Fried had implanted electrodes for clinical purposes.-"The findings suggest that a single neuron—far from being a simple switch—may possess enormous computational power. Meaningful messages might be conveyed not just by hordes of neurons screaming in unison but by small groups of cells whispering, perhaps in a terse temporal code.-***-"This analysis implies that each individual psyche is fundamentally irreducible, unpredictable, inexplicable. It is certainly not simple enough to be extracted from a brain and transferred to another medium,..."-Comment: The brain will never be completely understood, but it works actively in cooperation with us.