Researching how neural pathways are involved with visual processing

6/6/2012

Professor Martin Usrey has been named a Brain Research Foundation 2012 Science Innovation Award winner, with a $150,000 prize that will fund the development of a powerful and highly precise method for manipulating brain activity while simultaneously recording from the brain with functional magnetic resonance imaging (fMRI). Called optogenetics, the technique will be used by his team to research how neural pathways are involved with visual processing.

“It was extremely exciting to get the news because this is something that is too risky for NIH funding,” the neurobiologist says. “This innovation award allows me to delve into the riskier but innovative side of a technology.”

Usrey was highly honored to receive the award in its inaugural year. According to the Brain Research Foundation, the intent is to support research ideas or strategies that are so cutting edge that they may not yet be considered for other sources of funding.

“This particular award was to take two very powerful technologies and combine them in order to address questions in a way that hasn’t been done before,” Usrey says, speaking of the combination of optogenetic stimulation and fMRI recording.

Only a few years old, optogenetics involves combing the DNA of phototaxic bacteria with a viral vector in order to transfect neurons with light-sensitive ion channels. When these channels are incorporated into the membranes of brain neurons, the neurons become photosensitive. Light can then activate or deactivate the neurons depending on the color of the light.

“With millisecond precision we can control the cells that are active with high specificity, both temporally and spatially,” Usrey says, adding that the method has no side effects for the study subject. “After the light goes off, the cells return right back to normal.”

He and his team will measure brain activity during optogenetic stimulation using UC Davis’ new and state-of-the-art fMRI machine, for which he thanks Dr. Cameron Carter, Director of the Center for Neuroscience and Professor of Psychiatry and Behavioral Sciences.

“He put in a grant to purchase an fMRI magnet and placed it immediately adjacent to our laboratory,” Usrey says. “Worth $3 million, it arrived last year and has really opened up the door for us to conduct new types of studies.”

Usrey hopes to fine-tune optogenetics methods so that the days of less precise and highly invasive manipulations are no longer necessary.

“At first, to study the brain, you would cut a piece out and ask how that affected behavior,” Usrey says. “After that, researchers would squirt drugs into the brain and wait to see the effects.”

In this study, Usrey will team up with Dr. George R. Mangun, Dean of the Division of Social Sciences and Professor of Psychology and Neurobiology, an expert on visual attention, to study the subclass of cortical neurons that provide feedback communication to the thalamus. These neurons are believed to play a critical role in our visual attention, but their role has yet to be directly tested.

“When our eyes look at our environment, we receive too much information for our brains to process efficiently. Visual attention is a process that allows organisms to regulate the flow of sensory information by “selecting” relevant information for continued processing and/or inhibiting irrelevant or distracting events”,” Usrey says. “We’ll be looking at what happens to that spotlight of attention when you activate or inactivate certain pathways.”

Usrey’s work will have implications far beyond visual processing. Cortical circuits play a crucial role in mediating complex behavior, and disruption of cortical processing underlies numerous disorders, including epilepsy, schizophrenia, and Alzheimer’s disease.

“The strategy and tools we develop will have broad application to all areas of neuroscience and provide a much needed bridge between molecular, cellular, systems, and cognitive neuroscience,” Usrey says.