Lens Design Enables Expanded View of Neuronal Activity
RALEIGH, N.C., July 18, 2016 — A novel lens for a two-photon imaging system is able to capture images of the brain that are almost 10 times larger than those captured through a conventional two-photon microscope. When incorporated into a two-photon imaging system, the advanced lens demonstrated an expanded field of view of more than 9.5 mm2. In contrast, conventional two-photon microscopy systems are limited in their field of view to approximately 1 mm2.
The lens design was the result of a partnership melding neuroscience and electrical engineering. To study how mice process visual input, researchers at University of North Carolina at Chapel Hill (UNC-Chapel Hill) needed to view neuronal activity across multiple areas of mice brains simultaneously. When they were unable to achieve this goal using a conventional two-photon microscope, they contacted a team of electrical engineers at North Carolina State University (NC State) for help.
The NC State team designed and assembled an optimized scan engine, objective and two independently positionable, temporally multiplexed excitation pathways. They used the custom-designed microscope to measure activity correlations between two cortical visual areas in mice during visual processing and found that the microscope was able to perform rapidly reconfigurable simultaneous scanning of widely separated neuron populations.
The advance in lens design will allow researchers to view activity of widely separated populations of neurons at the same time, addressing one of the challenges of two-photon imaging of neuronal activity: the limited field of view.
The research was published in Nature Biotechnology (doi:10.1038/nbt.3594).
- A quantum of electromagnetic energy of a single mode; i.e., a single wavelength, direction and polarization. As a unit of energy, each photon equals hn, h being Planck's constant and n, the frequency of the propagating electromagnetic wave. The momentum of the photon in the direction of propagation is hn/c, c being the speed of light.
- A transparent optical component consisting of one or more pieces of optical glass with surfaces so curved (usually spherical) that they serve to converge or diverge the transmitted rays from an object, thus forming a real or virtual image of that object.
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