by K. C. Jaehnig, Media & Communication Resources
 

A young psychologist whose research is helping to solve the puzzle of how hormones and certain drugs can affect memory has won SIUC's Outstanding Dissertation award for 2000.

Kevin Clark received the honor for studies showing that stimulation of the vagus nerve, which carries information from internal organs to the brainstem, can enhance memory in both rats and humans—findings so significant that portions of his dissertation have already been published in the journals Nature Neuroscience and Neurobiology of Learning and Memory. 

Clark’s work is the latest in a series of memory-related studies conducted by SIUC faculty and their doctoral students. SIUC psychologists Robert Jensen and Douglas Smith are investigating whether vagus nerve stimulation can help patients with brain damage recover more quickly—research to which Clark’s work has made a significant contribution.

Influenced by previous findings pointing to the vagus nerve as a possible pathway through which memory-enhancing hormones might exert their effects, Clark set out to show that electrically stimulating this nerve could improve learning and memory in rats.

The successful conclusion of that experiment led him to set up a second study. This one demonstrated that positive effects obtained in the first trials came about solely because of vagus nerve stimulation effects on the brain—not, as some critics argued, because that stimulation had triggered the release of glucose or certain hormones.

"These two studies were technically difficult and of considerable significance and in themselves might have been sufficient for some dissertations," wrote Jensen in his nominating letter, noting that both had been cover stories in the journal Neurobiology of Learning and Memory. "However, there is much, much more in Kevin’s research."

Still using lab rats, Clark next showed that vagus nerve stimulation increased neural activity in the hippocampus, an area in animal and human brains that plays a role in the ability to learn.

Clark got the chance to test his hypothesis on humans after meeting SIUC physician Dean Naritoku, who was conducting clinical trials at the School of Medicine in Springfield of vagus nerve stimulation as a means of controlling epileptic seizures. 

With Naritoku’s help, Clark was able to show that people who were given sets of words to remember could recall those words that had been paired with vagus nerve stimulation better than those words that had not been paired with stimulation. It was this portion of his work that was published in Nature Neuroscience.

"Many scientists go a lifetime without being able to publish in such a prestigious journal," noted Smith, who co-chaired Clark’s dissertation committee. 

Clark, who also earned his master’s from SIUC, completed his doctoral degree in May 1999 and has since studied at the Max Planck Institute in Tübingen, Germany. 

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