'Giant' Neuron Regulates 50,000 Other Neurons 81
Scottingham sends this quote from PhysOrg:
"A single interneuron controls activity adaptively in 50,000 neurons, enabling consistently sparse codes for odors (abstract). The brain is a coding machine: it translates physical inputs from the world into visual, olfactory, auditory, tactile perceptions via the mysterious language of its nerve cells and the networks which they form. Neural codes could in principle take many forms, but in regions forming bottlenecks for information flow (e.g., the optic nerve) or in areas important for memory, sparse codes are highly desirable. ... This single giant interneuron tracks in real time the activity of several tens of thousands of neurons in an olfactory centre and feeds inhibition back onto all of them, so as to maintain their collective output within an appropriately sparse regime. In this way, representation sparseness remains steady as input intensity or complexity varies."
Nice summary ...not! (Score:5, Insightful)
"We studied the olfactory system of locusts, and found that all of the smell information seems to pass through a single neuron with a lot of incoming connections. This single neuron does not send outgoing signals in spikes as most other neurons do, but instead releases a chemical that suppresses other neurons. It uses this method to sort-of "average" all of the incoming signals together. Also, this system involves a feedback loop. We think that this whole arrangement is set up to generate sparse-codes, which is our favorite way to reduce information down to a small number of dimensional values. We hope that mammals use similar systems, and that this might eventually help lead to an understanding of how brains reduce large amounts of information into small concepts."
Re:So the brain has supernodes? (Score:5, Insightful)
One more commonality: The media industry hates when you use it.
Re:Single Point of Failure? (Score:5, Insightful)
It's worth noting that this is still considered largely correct. The most successful life form on the planet is a fly, and most successful mammal is a rat.
A great example of minimalism working in favor of evolution in humans is our intestinal tract. If you look at most large apes that bear close resemblance to humans, they can eat food that would cause us to get sick and die, in spite of being similar omnivores to us humans. Why? Because at the end of our evolution, we discovered fire. Cooking causes most proteins to break up as well as largely disinfect the food. Adapting to this, the humans who survived the evolutionary selection were the ones who had vastly downsized and simplified intestinal tract, that couldn't consume much of the uncooked food that larger could. This means that where apes and some other prehistoric evolutionary branches of human race ate raw food, and had to use much more energy digesting it, in turn causing it to need more food for same amount of work, humans who survived were far more efficient. This is very noticeable when you look at gorillas for example - they have large pot bellies, mainly because of sheer size of their intestinal tract.
In this regard, if humans were to lose knowledge of fire, they would likely become extinct, as our ability to eat uncooked food is severely hamstrung by our evolution. But as long as we can cook, we are far more energy efficient then competition. As a result, we can afford a much larger brain, that consumes much more energy. A very common argument in modern evolutionary theory is that discovery of fire, and consequent evolution of our intestinal tract have been a requirement for evolution into modern homo sapiens, as without it, we would be unlikely to be able to successfully support our current brain's energy needs.
In this regard, the requirement for two eyes is actually not about conservation - it's about need for stereo vision for successful hunting. The proper argument is that we don't have a third eye in case of loss of one eye (and subsequent severe diminishing of ability to hunt) because of minimalism - those who lose an eye will likely die off but majority will be able to die of other reasons.