Campus / News / Student Research / February 28, 2008

Cocaine on the brain

Venture into the depths of the SMC psychology department and you will find senior Andy Arnold surrounded by red-eyed rats and busy at work on his honors project. Arnold is working to discover if “the insular Cortex [of the brain] mediates cocaine craving.”

Arnold, a neuroscience major, became interested in this question while taking behavioral pharmacology with Heather Hoffman. Arnold came across the report “Damage to the Insula Disrupts Addiction to Cigarette Smoking,” published in Science Magazine in January of 2007. The report outlines how researchers in California found that the vast majority of smokers in the study who had their insular cortex destroyed during a stroke quit smoking and reported no cravings for nicotine.

This was “the first report to indicate insula in drug cravings,” said Arnold. The discovery was “really crazy because it just was really clear the insula was mediating this craving.” Intrigued by the study, Arnold sent an e-mail to the researcher asking for more information, receiving an encouraging reply.

Arnold had received the Ford scholarship and was planning a project centered on yoga, but changed it after reading the study. To test the correlation, he decided to see how rats, once addicted to cocaine, would react once having their insula destroyed. Arnold chose to use a Pavlovian-Instrumental Transfer test (PIT.)

The test occurs in five stages. During the first stage, the instrumental stage, Arnold teaches the rats to associate lever pushing with receiving a liquid mixture of cocaine and sugar water, (the sugar is to help with the bitter taste of the cocaine.) The next stage, the Pavlovian conditioning, teaches the rats to “associate the smell of lemon with the feeling of cocaine.” The third stage is the actual PIT test, where Arnold tests to see if the rats will press on the lever in the hope of receiving cocaine when they smell the lemon scent. They do not receive cocaine during this stage.

After this the rats undergo stereotaxic surgery. Arnold uses a neurotoxin to destroy the insula tissue, before stitching the rats up. He then lets the rats recover for about ten to 12 days, giving them plenty of water during this period.

“We don’t want any infections,” said Arnold.

He then reconditions the rats and subjects them to a second PIT test. Seven of Arnold’s rats went through this process, and all showed “results suggestive” that Arnold’s hypothesis could be correct. But he understands he will need to test more to come up with a more definitive understanding. He started his second batch of test rats Tuesday.

Arnold was met with challenges along the way. He worked with science technician Clarence Kuster, to design a machine “to shoot different odors into the cage through tubes.”

“I stopped naming my rats after a while, that didn’t take long, [I] named the first four, when Candice and Beatrice died I decided to stop.”

“I do have a relationship with my rats,” he said. “I just really see them as a mechanism for better understanding the human drug addiction problem…that’s harsh calling them a mechanism, but I guess it’s true.”

Arnold started working on the project last summer, setting up a pilot study with Hoffman “to figure out exactly how to run it.”

It was “nice to get started in the summer,” said Arnold to be able to start the project when returning to school.

“Heather’s been really awesome through this whole experience…really encouraging and helpful setting up protocol [and with] guidance.” Neil Schmitzer-Torbert, a professor at Wabash College in Indiana, is on Arnold’s honor’s committee as well as biology professor Esther Penick.

Arnold estimates that he spends 25 to 30 hours a week working on his honors project, that in addition to taking one class (plus1.5 credits of honors,) SNU activities, and eight hours working at the library. His hours spent working on honors goes up during surgery.

Overall, Arnold “was really surprised to be able to do novel scientific research here at Knox.” It’s “been cool to be doing cutting edge work in the field,” adding “it has really taught [him] the collaborative nature of academia.”

He plans to attend graduate school for a Ph.D, but is first applying for a Fulbright to return to Denmark where he wants to study at the Research Center for Brain Injury Rehabilitation.

Klayr Valentine-Fossum


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