Monday, June 20, 2005

Early candidate application for NCC simulation

The Blue Brain Project cites one figure for the number of neurons in an NCC as being over 60,000.

It's worth noting that the experiment in which rat brain neurons spontaneously learned to fly a virtual F-22 required only 25,000 neurons.

Thursday, June 16, 2005

Structure to the human brain, scale-free and otherwise

From the Blue Brain Project's page on the Neocortical Column (NCC):

The Neocortical Column (NCC) marks the quantum leap from reptiles to mammals and therefore constitutes the birth of mammalian intelligence and the emergence of human cognitive capabilities. The neocortex is the brain region that allows mammals to adapt so efficiently to a rapidly changing world.
The NCC is considered to be the smallest network of neurons that act as a functional unit exhibiting some of the most complex functions of the brain - the NCC is the elementary building block of the mammalian brain.
The NCC was such a highly successful circuit design, that it was repeatedly duplicated to become almost 80% of the human brain (millions of columns were added). In humans, the duplication continued at such a pace that the neocortex started folding in on itself to make more space for newly added columns, thus forming the highly convoluted human brain. (see The Brain: Our Universe Within).

It seems the ultimate ambition is for NCC function to be abstracted away, with the resulting simulation of human neural structure assembled in a scale-free manner. Cf. the abstract of a relatively recent paper titled "Scale-free brain functional networks":

Functional magnetic resonance imaging (fMRI) is used to extract functional networks connecting correlated human brain sites. Analysis of the resulting networks in different tasks shows that: (a) the distribution of functional connections, and the probability of finding a link vs. distance are both scale-free, (b) the characteristic path length is small and comparable with those of equivalent random networks, and (c) the clustering coefficient is orders of magnitude larger than those of equivalent random networks. All these properties, typical of scale-free small world networks, reflect important functional information about brain states.

Friday, June 10, 2005

Possible blowback from European overfishing in West African waters

According to a piece in National Geographic News on November 11, 2004, researchers suggested that the EU's appetite for West African seafood may be leading to an increased reliance on bush meat.

Researchers say dwindling fish stocks due to trawling by foreign fishing fleets is a key cause of the increase in the "bush meat" trade in Ghana.
The study, published tomorrow in the journal Science, claims to be the first to provide strong evidence of a link between local fish supply and bush-meat hunting...
Lead author Justin Brashares, assistant professor of ecosystems science at the University of California, Berkeley, says it's likely that other West African countries are similarly affected.
"If people aren't able to get their protein from fish, they'll turn elsewhere for food and economic survival," he said. "Unfortunately the impacts on wild game resources are not sustainable."

A press release from the WWF in 2003

The bush meat trade itself appears linked with recent outbreaks of ebola in west central Africa and the rise of new HIV strains in Cameroon which are not detected by current tests.

Thus, the European appetite for fish may be contributing to an increased rate of disease outbreaks. Not is Europe insulated. Bush meat is making its way back to the UK; other European countries are likely similarly affected.

Given current trends, I would expect overfishing to continue.

West Africa has a large indigenous fishing effort trawling its waters but it is the activities of EU-subsidised and other foreign fleets that have been criticised by conservation groups for accelerating the decline of fish stocks in the region...
The Science study notes that the European Union maintains the largest foreign presence off the coast of West Africa, with EU fish catches increasing 20-fold from 1950 to 2001, and financial subsidies jumping from $6m in 1981 to more than $350m in 2001.