21 November 2011

Brief Optogenetics Primer: All Cyborgs Now

Dr. Deisseroth shows me a video of a mouse placed in a cage with another mouse. The mouse is active and gregarious, showing interest in his new pal. A video of the same mouse, after a flash of blue light has boosted his brain's "excitation" cells (a type of overactivity found in autism), is remarkably different. After a moment's curiosity, he turns his back and shuffles into a corner. He remains remote, seemingly overwhelmed, and moves away when the other mouse gets close. For 30 minutes after that split-second burst of light, this mouse is not himself. _WSJ

Optogenetics is the combination of genetics and optics to control well-defined events within specific cells of living tissue. It includes the discovery and insertion into cells of genes that confer light responsiveness; it also includes the associated technologies for delivering light deep into organisms as complex as freely moving mammals, for targeting light-sensitivity to cells of interest, and for assessing specific readouts, or effects, of this optical control.

What excites neuroscientists about optogenetics is control over defined events within defined cell types at defined times—a level of precision that is most likely crucial to biological understanding even beyond neuroscience. The significance of any event in a cell has full meaning only in the context of the other events occurring around it in the rest of the tissue, the whole organism or even the larger environment. Even a shift of a few milliseconds in the timing of a neuron's firing, for example, can sometimes completely reverse the effect of its signal on the rest of the nervous system. And millisecond-scale timing precision within behaving mammals has been essential for key insights into both normal brain function and into clinical problems such as parkinsonism. _Karl Deisseroth _ Scientific American
Karl Deisseroth is at the forefront of the exciting science of brain control via light triggered gene expression. The video above presents a quick overview, and the Scientific American article by Deisseroth himself gives a bit more background information.

Researchers are taking this new tool and moving quickly to discover how the deep neural brain codes are transmitted and understood from one brain region to another. Here is the Nature abstract from some rather recent research from Deisseroth's lab:
Neuronal activity patterns contain information in their temporal structure, indicating that information transfer between neurons may be optimized by temporal filtering. In the zebrafish olfactory bulb, subsets of output neurons (mitral cells) engage in synchronized oscillations during odour responses, but information about odour identity is contained mostly in non-oscillatory firing rate patterns. Using optogenetic manipulations and odour stimulation, we found that firing rate responses of neurons in the posterior zone of the dorsal telencephalon (Dp), a target area homologous to olfactory cortex, were largely insensitive to oscillatory synchrony of mitral cells because passive membrane properties and synaptic currents act as low-pass filters. Nevertheless, synchrony influenced spike timing. Moreover, Dp neurons responded primarily during the decorrelated steady state of mitral cell activity patterns. Temporal filtering therefore tunes Dp neurons to components of mitral cell activity patterns that are particularly informative about precise odour identity. These results demonstrate how temporal filtering can extract specific information from multiplexed neuronal codes. _Nature
More information on this recent research from press release information

Optogenetics is a tool of discovery and a tool of control. Light can trigger changes in cells, but it can also serve to send return information about the state of cells back to the sender. Even more usefully -- for cyborg controllers -- light does not interfere with electromagnetic imaging methods such as EEG, EMG, or MRI. One can send controlling signals to the cyborg while simultaneously observing reactions to the signal, via multiple channels of observation.

Always keep in mind the "genetic" aspect of optogenetics. This type of cyborg has been "branded" with new genetic programs which will go on operating for as long as they can be triggered effectively. These new programs will eventually be able to completely override many of the innate "brain programs" of the cyborg, allowing controllers to use the entire cyborg as something of a "social probe," or a social agent.

This should demonstrate the superiority of cyborgs over zombies. Zombies operate on a limited autonomy and competence, with generally destructive effects. Cyborgs, on the other hand, can possess significant competence of a revisable nature, while sacrificing as much or as little autonomy as necessary for the task at hand.

It is the future. Why fight it? Resistance is futile. ;-)

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Blogger Will Brown said...

The man's trying to build a Neuraliser? What color is his suit?

Monday, 21 November, 2011  

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