Our eyes are constantly moving, which blurs the image of the world across the retina. Shown here is a neural network model of the visual cortex that removes this motion blur by using neural connections that are matched to the statistics of eye movements. (see Pitkow et al., e331).

To learn more about where seeing occurs, Webvision has a discussion of “Roles of amacrince cells,” which are “cells of the vertebrate retina [which] are interneurons that interact at the second synaptic level of the vertically direct pathways consisting of the photoreceptor-bipolar-ganglion cell chain.” Just to take a peek at how the eye works, or to study in detail, the amacrince page is an excellent open resource created at the John Moran Eye Center, University of Utah: WEBVISION: The Organization of the Retnia and Visual System.

The University of Texas also has some outstanding online materials for learning about motion perception, including this page in a Center for Perceptual Systems. Even for beginning and young students, spending some time with webpages like these introduces basic ideas and tickles the curiosity about vision and the biology from which it arises.

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By activating multiple fluorescent proteins in neurons, neuroscientists at Harvard University are imaging the brain and nervous system as never before, rendering their cells in a riotous spray of colors dubbed a “Brainbow.” . . .

“There are few tools neuroscientists can use to tease out the wiring diagram of the nervous system; Brainbow should help us much better map out the brain and nervous system’s complex tangle of neurons,” Lichtman said.

Equal parts pointillism, fauvism, and abstract expressionism, the resulting images could also help scientists identify how brain wiring goes awry in many different diseases. Brainbow could also help track the complicated development of the mammalian nervous system, currently understood only in general terms. This, in turn, could elucidate the origins of the many brain disorders that arise early in development.

Drawing upon a mix of genetic tricks and special proteins that cause cells to glow, Brainbow uses a well-known genetic recombination system known as Cre/lox in a new way, to shuffle genes encoding green, yellow, orange, and red fluorescent proteins. The researchers painstakingly assembled the Brainbow transgene from snippets of DNA, and inserted it into neuronal DNA. As they predicted, the cut-and-paste recombination occurred totally at random, in the process assigning scores of different colors to neurons. This variation makes neurons leap out from one another visually under ordinary confocal microscopy.

Photonics.com picked up on the Brainbow story from the scientific imaging perspective, with an article called ‘Neurons Glow in ‘Brainbow’: “Brainbow allows researchers to tag neurons with roughly 90 distinct colors, a huge leap over the mere handful of shades possible with current fluorescent labeling. By permitting visual resolution of individual brightly colored neurons, this increase should greatly help scientists in charting the circuitry of the brain and nervous system.”

Chemistry World calls its report on this research Brain’s wiring seen in Technicolor, and includes nine still images of different Brainbow perspectives.

If you visit the the Brainbow links above, and others such as a report today in the New York Science Times, you will note that they all mention that Brainbow is the cover story of this week’s Nature magazine. The report in Nature magazine is not, however, a learnode (a node for learning in the open Internet) because it is not open. All of the other sources mentioned, and the supplementary links that they offer are open. What makes Nature not open is more than the fact that it is closed except to paid subscribers and purchasers of its Brainbow article. The Nature article is also not open because it cannot be a node in a network cluster of Brainbow links. Only open links can be learnodes in subject clusters where the links enrich each other and keep each other up-to-date. By analogy to the neuron image above: the open articles interconnect like the different colored neurons do; the Nature article is an isolated dot with no extending dendrite.
GOTO more biology learn node clusters.

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