Lasers blast away cocaine addiction in rats

Researchers with the U.S. National Institute on Drug Abuse (NIDA) have discovered a way to use lasers to turn cocaine addiction in rats on and off like a switch.

Cocaine abuse has severe consequences. The drug increases brain activity, but it also ends up causing decreased activity in the prefrontal cortex — essentially the 'front-most' part of the brain, which handles both decision making and impulse control. This leads an addict to seek out more of the drug, and the more drug they use, the worse the 'deficits' in the prefrontal cortex become, creating a serious and potentially-deadly loop of behaviour.

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Studying the brains of both addicted and non-addicted rats, the scientists saw how the drug affected the firing patterns of nerve cells. They then modified the affected nerve cells to respond to light — a technique called 'optogenetics' — so that they would switch on or off when exposed to a laser.

For the cocaine-addicted rats, these cells were already 'switched off' by the drug use, but when the scientists hit them with the laser light, they turned back on, and the rats' cocaine-seeking behaviour stopped. For the non-addicted rats, these cells were normal, but when they were also subjected to the laser light they turned off, causing the non-addicted rats to exhibit addicted behaviour.

"This is the first study to show a cause-and-effect relationship between cocaine-induced brain deficits in the prefrontal cortex and compulsive cocaine-seeking," said Dr. Billy Chen, first author of the study, in an NIDA press release. "These results provide evidence for a cocaine-induced deficit within a brain region that is involved in disorders characterized by poor impulse control, including addiction."

The scientists are now looking to translate these methods into use for humans, but they wouldn't be zapping people's brains with lasers. Instead, according to Dr. Antonello Bonci, who is the lead author of the study, more non-invasive methods would be used — such as 'transcranial magnetic stimulation (TMS)' apparently, according to a UC San Francisco statement, a technique that uses short magnetic impulses to stimulate brain activity.

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"This exciting study offers a new direction of research for the treatment of cocaine and possibly other addictions," NIDA Director Dr. Nora D. Volkow said in the press release. "We already knew, mainly from human brain imaging studies, that deficits in the prefrontal cortex are involved in drug addiction. Now that we have learned how fundamental these deficits are, we feel more confident than ever about the therapeutic promise of targeting that part of the brain."

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