24 October 2008

Neuron Logic Gates, Grobycs, Mind Control, More

Researchers at the Weizman Institute of Science are building logic gates out of neurons grown on a specially coated and etched glass plate. The brain neurons are caused to grow and send out controlled numbers of axons along small channels in a micro-circuit, trained to function as an "AND" logic gate.
The gate is made from a network of neurons in a square shape approximately 900 micrometres on a side. Three of the sides form a "horseshoe" 150-micrometres wide, and packed with neurons. On the fourth side an isolated neuron island is linked to the other sides by two thinner bridges (see image, top right).

Neurons send their wire-like extensions that carry signals – axons – across those narrow bridges to the neuron island.

When stimulated with a small dose of a drug, the neurons send signals around the circuit. An ion blocker is used in the centre of the horseshoe to electrically isolate one side from the other.

By changing the width of the bridges, the researchers are able to control how many axons link to the neuron island, and tune their device to behave like an AND gate.

The neurons on the island only produce an output after receiving signals through both of the thin bridges. Like a natural system, the device transcends the performance of individual neurons – achieving 95% reliability from a collection of 40% reliable components. _NS
It is easy to visualize the creation of more advanced neural logic devices designed to function as natural interfaces between whole brains and electronic controllers and prostheses.

Stanford researcher Karl Deisseroth is working on methods of "switching" brain states using light to control genetically engineered proteins in brains.
"Here's what happens when we turn on the light," Karl Deisseroth says. He points to a mouse, ordinary save for the thin optical fiber protruding through its skull. When a lab tech presses a lever, blue light shoots through the fiber, and the mouse -- which had been sauntering straight ahead -- starts to run in circles. "He's doing that because the blue light turns the neural circuit on," Deisseroth explains. "As soon as we stop the stimulation, he'll walk straight again." _PopSci
Oxford researcher Gero Miesenbock is also pursuing methods of controlling neural activity with light.
There is a whole range of approaches that becomes possible with the ability to control specific groups of neurons. This allows a connection to brain tissue that is noninvasive and physiological. You can get wiring diagrams of neuronal circuits. You can apply spatiotemporal patterns of input activity and measure what kinds of inputs a target cell or a group of target cells is looking for. This would be not just a mapping of anatomic connectivity but rather a way of deducing the input/output characteristics of a circuit. A still higher level of complexity would be to see what exact features of activity patterns are relevant for perception, action, cognition, memory, and so forth. _JCB
Scientists see this approach as a sophisticated way to probe and map neural circuits in vivo, on finer and finer levels. Ultimately it would also allow sophisticated control of behavior, and probably non-motor cognitive activity as well.

Scientists have already found ways to observe the development of very young mammalian brains as early experience shapes brain structure. From there it is only a short step to controlling the development of the young brain in specific ways toward specific ends. A brain developing in isolation from the rest of the animal--connected to the outside world only by reasearcher-controlled inputs--would allow a wide range of investigative manipulative control of brain development.

If you add the ability to selectively dull or eliminate specific memories or functional circuits to such an extensive library of brain circuitry, you begin to have significant control over what that brain can or will do.

The placement of artificial neural connections from motor neurons in the brain directly to voluntary muscle groups is already allowing the study of brain plasticity in motor neuron circuits in a sophisticated way. In the experiment linked above, nerves to the target muscles had been temporarily numbed. But in future experiments it is likely that nerve connections--first peripheral nerves, then entire spinal cords--will be permanently severed to allow extended study of multiple artificial bypass circuits to various synergistic and antagonistic muscle groups, to test the limits of motor neuron circuit plasticity.

A Grobyc is simply a Cyborg spelled backwards. It is the use of neural nets or animal brains to control machines. To make a Grobyc, one starts with the machine and finds ways to augment it with biological neural networks or animal brains. A Cyborg is a biological organism that is augmented with artificial prostheses to allow continue or augmented function as that organism. With Cyborgs, you start with the biological organism. The two concepts are mirror images of sorts.

This is only the beginning of the beginning. If you are a bit uneasy about some of the implications of this research--given the clearly unscrupulous nature of many politicians, judges, intellectuals, academics, and other highly influential people, you are not alone. Pay attention.

Note from Alice Finkel: The past two articles on this blog are based upon emails received from an account that Al Fin sometimes uses when he wishes to remain anonymous. That is good news, since if he has the time and freedom to post email, and chooses to spend that time on blog postings, he is not likely to be under any duress. I suppose I will have to drive up to Mr. Fin's place and take Valerie out of hibernation.

Xtra: Follow this link to find out how to get a $75 discount on the price of a ticket to tomorrow's Singularity Summit in San Jose.

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