Construindo um neocórtex

Steve Quartz deve ser o nome do publisher dessa matéria sobre o Blue Brain Project, mas não tenho certeza. Henry Markram, chefe desse projeto, está tentando construir um neocórtex de rato para estudos mais aprofundados do funcionamento do cérebro e também como prelúdio para uma iniciativa semelhante quanto ao cérebro humano.

The quantum leap
Neurons receive inputs from thousands of other neurons, which are intricately mapped onto different branches of highly complex dendritic trees and require tens of thousands of compartments to accurately represent them. There is therefore a minimal size of a microcircuit and a minimal complexity of a neuron’s morphology that can fully sustain a neuron. A massive increase in computational power is required to make this quantum leap — an increase that is provided by IBM’s Blue Gene supercomputer2 (FIG. 1). By exploiting the computing power of Blue Gene, the Blue Brain Project1 aims to build accurate models of the mammalian brain from first principles.

The first phase of the project is to build a cellular-level (as opposed to a genetic- or molecular-level) model of a 2-week-old rat somatosensory neocortex corresponding to the dimensions of a neocortical column (NCC) as defined by the dendritic arborizations of the layer 5 pyramidal neurons. The quest to understand the detailed microstructure of the NCC started more than 100 years ago with the pioneering work of Santiago Ramón y Cajal (1854–1934). This work, which was continued by a series of prominent anatomists, has provided a wealth of data, but the combination of anatomical and physiological properties of neurons was missing. Alexandra Thomson performed the first paired recordings in the neocortex, allowing simultaneous characterization of the morphology and physiology of individual neurons as well as the synaptic connections between many neurons33. The combination of infrared differential interference microscopy in brain slices34,35 and the use of multi-neuron patch-clamping36 allowed the systematic quantification of the molecular, morphological and electrical properties of the different neurons and their synaptic pathways in a manner that would allow an accurate reconstruction of the column.

http://www.hss.caltech.edu/~steve/markham.pdf

Mas não deixe de ver o mesmo projeto (mas com apresentação completamente diferente, para melhor) de Henry Markram, aqui. Um artigaço de Markram, de oito páginas, explica tudo desde o começo , e vale a pena dar uma olhada. Pode ser visto nesse aqui.

Alan Turing (1912–1954) started off by wanting to “build the brain” and ended up with a computer. In the 60 years that have followed, computation speed has gone from 1 floating point operation per second (FLOPS) to over 250 trillion — by far the largest man-made growth rate of any kind in the ~10,000 years of human civilization. This is a mere blink of an eye, a single generation, in the 5 million years of human evolution and billions of years of organic life. What will the future hold — in the next 10 years, 100 years, 1,000 years? These immense calcu lation speeds have revolutionized science, technology and medicine in numerous and profound ways. In particular, it is becoming increasingly possible to simulate some of nature’s most intimate processes with exquisite accuracy, from atomic reactions to the folding of a single protein, gene networks, molecular interactions, the opening of an ion channel on the surface of a cell, and the detailed activity of a single neuron. As calculation speeds approach and go beyond the petaFLOPS range, it is becoming feasible to make the next series of quantum leaps to simulating networks of neurons, brain regions and, eventually, the whole brain. Turing may, after all, have provided the means by which to build the brain.

E por aí vai. Imperdível!