By training lab rats to learn complex maze paths and tracking their activity over time, psychology professor Kyle Smith used optogenetics to identify the cells responsible for habit formation. Smith, who joined the faculty this summer, presented his work in the June 27 issue of the journal Neuron.
Smith found that habitual behaviors could be prevented by turning off certain neurons in the cortex. At the Massachusetts Institute of Technology, he worked under professor Ann Graybiel to learn the optogenetics technique and perform his research.
"The brain works in complex patterns in reflection of changes in activities, and this allows you to gain some control over that," Smith said.
After training the rats, Smith then over-trained them until they formed habits. He tracked their activity and used optogenetics to figure out the brain areas that are important to habit formation and how rapidly behavior alters in response to different manipulations.
Smith found the habit-forming cells in the infralimbic cortex, the area that his team changed with the optogenetics, and the striatum.
At Dartmouth, Smith plans to explore topics including addiction and brain circuitry and use the techniques he learned at MIT to answer new research questions.
"Now that we have a good sense of what the brain is doing with normal habit formation, maybe we can go in and see what becomes dysfunctional in the addictive state," Smith said.
At the College, he hopes to return to reward and motivation studies he conducted at the University of Michigan as a PhD student. He said he would like to see his work with habit formation complement his prior research.
"Habits are insensitive to bad consequences, so maybe there's something wrong with the rewards system and maybe we can handle it," he said.
Smith plans to have his lab running by early September. A post-doctorate researcher, a PhD student and two undergraduate presidential scholars will join him.
Adam Crego, Smith's PhD student, said he is excited to join Smith at the "frontier of optogenetics."
The technique uses viruses to transfer DNA that codes for light-sensitive proteins into brain cells. Then, researchers can enter the brain with lasers or fiber optics to expose certain cells to light, turning these areas on or off in the span of milliseconds.
Smith will teach undergraduate classes on reward and motivation in the winter and spring terms.
"I can give a good sense of what's going on in the field, what's hot and exciting," he said. "Dartmouth is unique because it's a research school but it also really emphasizes undergraduate teaching. The teaching quality here is very precise."
Crego, who will arrive on campus this week, called Smith's research impressive.
"I'm really excited to work with him and be a part of what he wants to accomplish at Dartmouth," he said.
Sam Gardner '15, a presidential scholar who will work in Smith's lab this fall, said he is interested in looking at the brain mechanisms of addiction.
