Cocaine-Induced Adaptive Behaviour Can Be Reversed Using Optogenetics

A team of Swiss scientists at the University of Geneva, has proven for the time that cocaine use is linked to physical brain changes. The study was led by Christian Lüscher and was published yesterday in Nature Magazine. The researchers also discovered methods that can be used to reverse the impact which cocaine has on the brain.

It is not a new thing that the firing potential of neurons that can be found in the nucleus accumbens (plays a central role in the reward circuit) is dramatically increased. The effects of cocaine like paranoia, delusions of persecution, visual hallucinations, auditory and tactile, increasing irrational acts, anger, distrust, depression and lack of motivation were long suspected to be caused by this increased neuronal firing potential but until now it has never been fully proven.

In order to prove the link between cocaine use and physical brain changes and also find a way to fight the effect of cocaine, Lüscher turned their attention to optogenetics process in which certain kinds of algae (which poses light-sensitive ion channels) are used to trigger a celular response to light. This property was used in this case to reduce the firing potential of neurons that was being increased by to cocaine use.

In their experiment, researchers expressed such light-sensitive ion channels in cortical neurons that normally communicate with neurons in the accumbens in laboratory mice that were administered several doses of cocaine. Then, the researchers fired laser pulses, causing a virtual storm of electrical impulses between the two types of neurons resulting in overkill, fact that determined the neurons to reduce their firing in response. This result effectively nullified the initial effect caused by the cocaine.


By repeating their experiment using several mice, and finding the same encouraging results each time (reduced firing potential of neurons and improved cocaine addiction specific behavior), researchers were able to establish a link between the two

While it seems that researches have found an effective method that can help cocaine addicts, it is not as simple as that. This particular techniques appears to be effective in mice that are newly addicted and whose brains have not changed dramatically.