Wednesday, March 25, 2015

"Excitability is a natural, physical property of nerve cells. In every neuron, the membrane potential undergoes ceaseless fluctuations in voltage. Those fluctuations are due in large part to the random release of vesicles of neurotransmitters at some of the neuron synapses. In the final analysis, this randomness arises fron thermal noise, whitch constantly rocks and rolls our mollecules around. One would think that evolution would minimize the impact of this noize, as engineers do in digital chips, when they set very distinct voltages for 0s and 1s that thermal noise cannot offset them. Not so in the brain: neurons not only tolerate noise but even amplify it – probably because some degree of randomness is helpful in many situations where we search for an optimal solution to a complex problem.

Whenever a neuron's membrane fluctuations exceed a threshold level, a spike is emitted. Our simulations show that these random spikes can be shaped by the vast sets of connections that link neurons into columns, assemblies, and circuits, until a global activity pattern emerges. What starts out as local noise ends up as a structured avalanche of spontaneous activity that corresponds to our covert thoughts and goals. It is humbling to think that the 'stream of consciousness,' the words and images that constantly pop up in our mind and make up the texture of our mental life, finds its ultimate origin in random spikes sculpted by the trillions of synapses laid down during our lifelong maturation and education."

from Consciousness and the Brain by Stanislas Dehaene

Friday, March 20, 2015

"Geese with their exceptional eyesight and wide field of vision, combined with their strident voices, make excellent guards against approaching strangers or predators since outsiders cannot calm them into silence. This was shown in 390 BC, when Rome was attacked by Gallic troops. It was the alertness of the holy geese housed in the temple of the city's fort that allowed the defenders to wake in time to resist the attacking enemy. Today, in the high Andes, Southeast Asia and many other places, geese replace guard dogs. In Europe, they are used to guard whiskey warehouses and sensitive military installations."

Saturday, March 07, 2015

From the Oxford English Dictionary entry for the adjective "ebon":
Pretty humiliating for Elizabethan poet Giles Fletcher that this mistake is still in the dictionary 420 years later.

One of the only other uses of the phrase "ebon thighs" that I could find is in this collection of (vile but interesting) racist satirical poems about the alleged sexual relationship between President Thomas Jefferson and his slave Sally Hemings.

Friday, March 06, 2015

"Metallic siege money of Leyden [was] struck in 1574 from a round coin die onto a diamond shaped silver planchet. As the supply of silver available for coinage dried up during the siege, Leyden continued to mint coins made from paper torn from prayer books. These cardboard 'notes' became the first paper money to appear in the Western world. Prior to this only the Chinese used paper money."

from "Siege Notes" by John E. Sandrock

"The latest use of leather for regal currency in Europe appears to be that of Russia. From about the eighth century onwards, as the commerce of that country expanded, and the supply of hides for exchange or barter purposes failed to keep pace with the monetary requirements of the people, the use of whole skins was discontinued, and skin snouts, ears and claws were substituted. These, in turn, gave place to pieces of skin or leather, which at first were of irregular shape about an inch square in size, but were afterwards issued in a circular form, and impressed with the government stamp. They continued in use until the reform of the currency in the latter part of the reign of Peter the Great, who died in 1725."

from "Leather Currency" by William Charlton