Sunday, August 17, 2008

Brain as Composter III

In reference to Brain as Composter II:

In this post the comparison between design principles in permaculture and how nature built a nervous system continue.

The next pair of design principles for good permaculture as laid out by Hemenway are to do with balance.
"3. Be redundant. "Repeat function," Bill would say. "Don't put all your eggs in one basket" is how my grandmother put it. Look at any nutrient cycle or watershed. There is always a variety of pathways by which an ecosystem can proceed about its business. In nature, this is done so that each organism occupies a unique niche in an ecosystem; yet if any one species is removed, everything it does for the whole will be accomplished by other organisms. A system's capacity for storage and resilience stems from its redundancy. It is the understanding of this principle, for example, that reveals that growing our food in monocultures, where everything hinges on the success of one species, is stupid and self-destructive."

Here is Angevine:
5. The Purposefulness of Neural Components

Every part of the nervous system has at least one function, often many more. Small parts of the CNS may play crucial roles, as in the extensive distribution and profound influence of axons from inconspicuous brain centers. The locus ceruleus ("blue spot") on each side of the fourth ventricle contains about 12,000 large melanin-pigmented neurons. These synthesize norepinephrine and release it in the cerebral cortex, cerebellum, and almost every other part of the CNS. Electrically, they are almost silent in sleep, hypoactive in wakefulness, and hyperactive in watchful or startling situations. They serve vigilance and attention to novel stimuli. They contribute, indirectly but no less crucially, to perceptual and cognitive functions. By contrast, immense structures make large but expensive contributions, as in the cognitive and motor abilities afforded us by the billions of neurons in our cerebral and cerebellar cortices.

4. Check your scale. Design and act within an appropriate size frame. Or, as Granny said,"Don't bite off more than you can chew." This is why permaculture starts at the backyard and works out.. to keep on a scale commensurate with our understanding. We are only responsible for the next step in whatever we are doing, and that step is always right before us, within our reach.
Issues of scale are tricky and require continuous attention to the consequences of a chosen scale. Small may be beautiful, but smallest is not always optimal. Some things can be done well only on a large scale (e.g., manufacture of photographic film), whereas others rapidly deteriorate with increasing scale (e.g., food preparation). The only cultural tools our society provides for evaluating scale are economic; these often lead to the selection of scales that are counterproductive, inefficient, and destructive.
(The reference to photographic film shows how long ago this article was published.)

1. Ubiquity

With 100,000 miles of nerve fibers the nervous system rivals the vascular system. Both pervade the body and function in harmony. By nerve impulses or circulating red and white cells, glucose, hormones and immune principles, they integrate body activity, protect the body, enhance its performance to met stress or demand, promote its growth and nutrition, and maintain its tone and vigor. The trunk and branches of both systems reflect body form. If either system and no other part of a person were visible, he or she would be recognizable. Density of innervation varies as the value of parts to sensory discrimination or motor control. In well-innervated areas (lips, fingertips) stimuli are sharply discriminated as to modality, intensity, and location, but in sparsely innervated areas (flanks, legs) these are less defined. Similarly, muscles vary in the ratio of motor neurons to muscle fibres. The higher the ratio, the more precise the control of the muscle and the movement it serves (a motor neuron may excite 2000 muscle fibers in a limb muscle or as few as 5 in extrinsic ocular muscles.

More to come.

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