Thursday, 1 August 2013

Jumping through hoops with a light flash

Whoever thought the time would come when the mind could be controlled with the flick of a light switch. Pretty cool huh! And I’m not talking about hypnotherapy.  Think “opto” and think “light”, think “genetics” and think “DNA”. Put them together and you give birth to the concept of “optogenetics”.

Optogenetics is the exciting new area of research where specific brain cells (neurons) can be manipulated to respond to light thereby linking the cell function to a light flash.
Imagine the concept of a football game on a console. Push a button on the controller and a player passes the ball. Push another button and it’s a shot. Such is the concept of optogenetics. Flash a blue light and the neuron responsible for signalling movement kicks the ball flash a yellow light and the neuron is activated to trigger a throw.

The brain is a complex network of cells known as neurons with each neuron having a unique role. The role of each of these trillions of neurons is yet to be deciphered. Put these neurons together and we have the ability to multi task; - Coordinate movement, listen and speak, read and write, sing and dance. The processing of this information in the brain occurs as a result of electrical impulses that travel between neurons. Like a 4 x 4 relay race, one neuron ignites the baton from the start line, passes on the baton to the next athlete and the last neuron finishes the race. If a member of the team drops the baton along the way, the race is lost. Each neuron has its own genetic composition and it is the genes that tell the neuron how to function via gene regulators. These gene regulators switch themselves on or off to control the neuron.  In the same way scientist can influence these regulators such that the ability to switch a neuron on or off is controlled externally, in this case the trigger is via a light flash. 

With optogenetics, a light sensitive protein known as channelrhodopsin which is originally found in unicellular green algae and responds to blue light by moving towards it, is engineered and injected into a chosen neuron. When blue light is then shone on neurons, the cell containing the channelrhodopsin is activated and it sends signals to other neurons in its team to perform a designated function. Light pulses are sent within milli - seconds of each other thereby allowing scientists to monitor the sequence of events with precision. This way when the baton is dropped along the way it is easy to pinpoint the culprit.
Opsins is the umbrella term describing light sensitive proteins. Others include halorhodopsin which is sensitive to yellow light.     

So of what benefit is this to mankind. If we can understand how each of these neurons controls brain function and we are able to identify and isolate the neuron responsible for a specific brain disease be it Parkinson’s, Alzheimer’s, Cerebral palsy and so on, that one defective gene can be corrected to perform its original function. Basically assuming loss of speech is caused by the breakdown of gene X in the brain, Channel rhodopsin can by inserted into the neuron containing gene X and when this gene shuts down blue light pulses can be sent to reactivate its speech function thereby bringing back ones speech.

Other methods exploring this concept of manipulating neurons include therapeutic gene manipulation and gene therapy. 

1 comment:

Horace said...

This is fantastic!