New ‘off switch’ for brain cells could aid epilepsy treatment

Posted Apr 28 2014 in Brain science; genetics

Scientists have found a new and more effective means of switching brain cells on and off, a discovery that could aid the future treatment of epilepsy and other neurological conditions.

A team from Stanford University has refined a technique they originally developed in 2005 that uses special proteins from microbes to pass electrical current into neurons, creating light pulses that can activate targeted brain cells with ease.

This method, known as optogenetics, was previously less effective at turning cells off than on. This led to the current research, which has seen the scientists re-engineer their light-sensitive proteins to switch cells off far more efficiently than before.

By bioengineering a family of proteins known as microbial opsins, the team was able to create an inner lining of positive amino acids to draw a flow of negative or inhibitory ions such as chloride into the targeted cells, before changing another amino acid to keep this new negative channel open.

This new technique is more effective at inhibiting neuronal activity based on chloride conductance, offers greater sensitivity to light and the ability to stay open for longer periods, maintaining inhibition even without light.

It is thought that this discovery will enable researchers to better understand the brain circuits involved in behaviour, thinking and emotion, as well as allowing neuroscientists to apply a brake in any specific circuit with millisecond precision.

Merab Kokaia, a professor at Lund University Hospital in Sweden, said: “These features could be much more useful for behavioural studies in animals, but could also become an effective treatment alternative for neurological conditions where drugs do not work, such as some cases of severe epilepsy and other hyperexcitability disorders.”

Epilepsy is caused by an excess of electrical activity in groups of neurons in the brain, manifesting as debilitating seizures of varying frequency and levels of intensity. In the UK, the condition is estimated to affect approximately one in 103 people and is usually diagnosed in childhood and in people over the age of 65, but can affect anyone at any age.

Posted by Anne Brown

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