A chemical treatment that makes neurons light responsive is described online this week in Nature Methods. This will allow researchers to selectively increase neuronal activity in animals. This is directly applicable to understanding the functioning of the nervous system and in the future it may have therapeutic applications.
Neuronal activity mediates behaviour in all animals with neurons but light doesn't normally regulate this activity. Neuroscientists have developed artificial methods however, that allow them to control neuronal activity with light. Existing methods for imparting long-term light sensitivity to neurons requires expression of foreign proteins. This can be done with genetic engineering but is difficult and not always feasible.
To overcome this limitation Richard Kramer and colleagues designed a chemical that permanently attaches to cell surface proteins and acts as a 'photoswitch'. Exposure to different colours of light flips the photoswitch between two different physical orientations. When the chemical is added to neurons it attaches to potassium channels on their surface and the light-induced flipping blocks and unblocks the channels to increase or decrease the excitability of the neurons.
This method will allow researchers to control the activity of almost any neuron by simply treating it with the chemical and shining light on the cell.
Richard H. Kramer (University of California, Berkeley, CA, USA)
Abstract available online.
(C) Nature Methods press release.
Message posted by: Trevor M. D'Souza