Scientists pilot new noninvasive brain control

Engineers at the Massachusetts Institute of Technology (MIT) have developed the first light-sensitive molecule that could be a breakthrough for optogenetics. The technology allows brain activity to be controlled by shining light on neurons, using light-sensitive proteins that can suppress or stimulate electrical signals within cells. 

However, this science relies heavily on a light source being implanted in the brain, where it can reach the cells to be controlled. The new technique, piloted by the team at MIT, uses a light source outside the skull, allowing neurons to be silenced noninvasively.

It is thought that this would make it possible to do long-term studies without having to introduce a light source into the brain. The so-called Jaws protein can also target a larger area of brain tissue at the same time, than the current technique.

The development of a new noninvasive approach could see optogenetics used for patients suffering with epilepsy and other neurological disorders, according to the researchers.

The team, led by Professor Ed Boyden, an associate professor of biological engineering and brain and cognitive sciences at MIT, published their findings in the latest issue of Nature Neuroscience.

However, these implanted light sources are not suitable for all experiments, such as studies of development where the brain changes size or neurodegenerative disorders. In addition, it is difficult to perform long-term studies of chronic diseases with these implants.

Professor Boyden and his colleagues used the natural world as inspiration as many microbes use opsins to detect light and react to their environment, with most of those commonly used in optogenetics responding best to blue or green light.

The team had previously identified two light-sensitive chloride ion pumps that respond to red light, allowing them to penetrate deeper into living tissue, but these the photocurrent was not strong enough to control brain activity.

They then tried to improve the photocurrent by looking for relatives of these proteins and engineered one by making a number of mutants, which resulted in Jaws. Jaws retained its red-light sensitivity but had a much stronger photocurrent.