A novel technique for rapidly mapping the epic network of connections between neurons in the brain has been developed by researchers. Infrared laser stimulation techniques were combined with functional magnetic resonance imaging in animals to generate mapping of connections throughout the brain.
“This is a revolution in detecting connections in the brain. The ability to easily map connections in the living brain with high precision opens doors for other applications in medicine and engineering,”
said senior author Anna Wang Roe, Ph.D., a professor in the Division of Neuroscience at Oregon Health and Science University. Roe led an international team of researchers in the United States and China. Roe splits her time between her lab at OHSU in Portland, Oregon, and Zhejiang University in Hangzhou, China, where she directs the Interdisciplinary Institute of Neuroscience and Technology.
Infrared Neural Stimulation
Researchers threaded a 200-micron optical fiber into the brains of research animals – in this case, cats and monkeys at Zhejiang and Vanderbilt, respectively – and stimulated specific areas of the brain, using pulsed near-infrared optics. They were then able to view the cascading series of connections through ultra-high-field MRIs measuring blood oxygen levels in various areas.
Traditionally, researchers have mapped these kinds of connections in the brain through a laborious process in which they injected dyes directly into the brain and reconstructed the connections post-mortem.
“It’s a very slow, expensive and time-consuming process,”
Roe said. Mapping of resting state connectivity, based on low-frequency correlations between brain areas, is commonly used for the study of brain networks; however, the relationship of these correlations to anatomical connectivity is still uncertain.
Information Flow Direction
The new technique opens doors for systematic, large-scale study of connection patterns within single individuals repeatedly and efficiently. It also enables researchers to determine the direction of information flowing within the brain, an insight critical for understanding information processing in the brain.
Roe said she believes the technique will greatly expand scientists’ ability to understand the brain and could accelerate development of artificial intelligence and technologies that use a brain-machine interface.
“If we can understand the organizing patterns in the brain, this could lead to some understanding of the general rules of connectivity,”
The research was supported by the National Natural Science Foundation, National Hi-Tech Research and Development Program, Zhejiang Provincial Natural Science Foundation of China, and National Institutes of Health.
Augix Guohua Xu, Meizhen Qian, Feiyan Tian, Bin Xu, Robert M. Friedman, Jianbao Wang, Xuemei Song, Yi Sun, Mykyta M. Chernov, Jonathan M. Cayce, E. Duco Jansen, Anita Mahadevan-Jansen, Xiaotong Zhang, Gang Chen, Anna Wang Roe
Focal infrared neural stimulation with high-field functional MRI: A rapid way to map mesoscale brain connectomes
Science Advances 24 Apr 2019: Vol. 5, no. 4, eaau7046 DOI: 10.1126/sciadv.aau7046
Top Image: Chris Nurse, Wellcome Images