Adonis Diaries

Lighting up the brain: Optogenetic technique?

Posted on: January 19, 2011

Lighting up the brain: Optogenetic?

Neurons in our brain do not react to light or photoelectric stimuli, unless particular proteins are implanted that are activated by light.

This field of neuro-science is called optogenetic.

Genes of proteins extracted from algae and vegetables are excited in the presence of light.  Modified neurons with photo sensitive proteins can be programmed to react to light, instead of the intrusive electrodes or drugs.

In 1990, the German Peter Hegemann demonstrated how the tail of a unicellular algae is activated by blue light.  Part of the membrane is filled with bundled up proteins in rope shape.  When a photon of light is directed at the protein, the molecule untangle and a microscopic hole appear through which electric ions enter and incite the tail of unicellular to move frantically.

Roger Tsien, professor at UC at San Diego, worked on isolating genes that produce photo sensitive proteins.  Thus, neuron are implanted with special protein that react to light and show the activated network of neurons to study how the brain functions.

One more difficulty was to be surmounted:

As you activate neurons you have got to deactivate them.  Ed Boyden discovered other particular proteins that deactivate neuron in yellow light.  There is another kind of proteins that light up green when activated and thus, permitting to receive information from neurons, instead of just sending signals for activation.  Consequently photo sensitive proteins can be used to sending signals and also generating signals.

Since we are dealing with 3 kinds of photo sensitive proteins (blue, yellow, and green lights), how about using this technique to hormones whose main functions are essentially to activate and deactivate nervous systems?

We can use the implanted proteins in the injections of hormones and watch the green proteins lighting up when activated.  This technique has several advantages:

First, we can try systematically all pairs of hormones that activate and deactivate an array of neuron networks; and second, we can study the corresponding tasks that activate an array.  Here is my experimental process:

1.  the brain is mapped into small neuron networks called “array

2. the array is implanted with “green protein” emitting the activated array

3. hormones with blue proteins are injected to selecting the ones that activate the array

4. hormones with yellow proteins are injected to sort out the ones that deactivate the array

5. subjects are submitted to various tasks in order to pinpoint the relevant or corresponding arrays in activation.

6.  once all arrays are mapped in functions and tasks, and the appropriate pairs of hormone discovered for activation and deactivation then, more complex tasks can be experimented with and interactions among arrays analyzed.

7.  if another color deactivation protein is discovered then, analysis of interactions would be facilitated.

8.  what goes with hormones could also be used with other molecules that are known to work as interrupter or transistors.

9.  the hormone method has an added advantage:  We can locate exactly the centers of activation and deactivation that might not be close to arrays.

Afflicted individuals with Parkinson disease that restrains them from movements, because the related neurons are attacked, can be cured in the near future:  targeted neuron networks may be implanted with photo sensitive proteins; the “Blue Proteins” or sensitive to blue light would activate the neuron and the “Yellow Proteins” would deactivate.

Brains of rats have been programmed this way; if the right special parts of the brain are implanted with the proteins then, the rat would run counter-clockwise and then stop when yellow lights are sent.  The rat would look at the experimenters wondering: “Tell me guys, what happened to me running crazily counter-clockwise?”

Since the Italian Galvani’s experiments on reactions of frog muscles to electrical impulses in the 18th century, study on brain functions basically relied on binary (on/off) activities of neurons and nerves.

Currently, experiments are done using non-intrusive tools and techniques such as photovoltaic (light) energy impulses.  The pores of particular axons of network of neurons and synapses in insects are activated by the light; the insect is thus programmed to behave as lights are on/off.

Research is focusing on selecting specialized network of neurons that can be activated and programmed so that particular functions of the brain are localized and controlled.  This strategy says: “let us investigate sets of neuron networks with definite functions.  As more networks are identified then, extrapolating procedures might shed better lights on how the brain function”.

It seems that this strategy in research is adopted frequently among teams of neuroscientists.

Basically,  although the brain does not function as current computers do, advanced computers are being tested, working on living organisms such as bacteria that are programmed with artificial intelligence rules.

Fundamentally, the brain and the nervous systems are activated in binary modes as computer by surges of energy impulses.

Note 1:  I have this strong impression that research on animals and insects are not solely based on moral grounds or ethical standards.

The practical premises are that animals are far more “rational” in their “well-behaved” habits than mankind:they are more adequate to logical designs.  Do you know that experiments are mostly done on male subjects (rats, insects, mamals…)?  They don’t have periods and mood change.

The variability (in types and number) in experimenting with particular animal species are vastly less systematic than experimenting with mankind:  For one thing, we are unable to communicate effectively with animal species and we have excuses to hide under the carpet our design shortcomings.

Note 2: I think there is a high positive correlation between longevity in the animal kingdom and level of “intelligence”.

Species that live long must have a flexible nervous systems that rejuvenate, instead of the mostly early hard-wired nervous systems in short-lived species. Thus, the brains of long-lived species are constantly “shaking”, meaning cogitating and thinking when faced with new conditions and environments.

Mankind mostly observed the short-lived species (with mostly hard-wired nervous systems) and applied control mechanisms on societies based on those “well-behaving” animals for control and organization models of communities of mankind.

It is of no surprise that control mechanisms on human societies failed so far in the long-term.

Man is endowed with a brain shaking constantly and rejuvenating most of his nervous cells.

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January 2011

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