High-speed 3D imaging of cellular activity in the brain using axially-extended beams and light sheets

• Published in: Current opinion in neurobiology Vol. 50; pp. 190 - 200
• Main Authors: Hillman, Elizabeth MC, Voleti, Venkatakaushik, Patel, Kripa, Li, Wenze, Yu, Hang, Perez-Campos, Citlali, Benezra, Sam E, Bruno, Randy M, Galwaduge, Pubudu T
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01-06-2018
• Subjects: Animals; Brain - cytology; Brain - diagnostic imaging; Humans; Imaging, Three-Dimensional - methods; Lighting - methods; Microscopy, Confocal; Models, Theoretical; Neurons - physiology; Neurons - ultrastructure
• ISSN: 0959-4388; 1873-6882
• DOI: 10.1016/j.conb.2018.03.007

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•Neuroscience needs faster in vivo volumetric microscopy approaches.•Axially-extended beams and light sheets provide alternatives to point scanning.•The performance and photobleaching benefits of axially extended illumination are modeled.•SCAPE microscopy leverages axial benefits for high-speed 3D imaging of neural activity.•SCAPE imaging in awake mouse brain and larval zebrafish brain is demonstrated.
As optical reporters and modulators of cellular activity have become increasingly sophisticated, the amount that can be learned about the brain via high-speed cellular imaging has increased dramatically. However, despite fervent innovation, point-scanning microscopy is facing a fundamental limit in achievable 3D imaging speeds and fields of view. A range of alternative approaches are emerging, some of which are moving away from point-scanning to use axially-extended beams or sheets of light, for example swept confocally aligned planar excitation (SCAPE) microscopy. These methods are proving effective for high-speed volumetric imaging of the nervous system of small organisms such as Drosophila (fruit fly) and D. Rerio (Zebrafish), and are showing promise for imaging activity in the living mammalian brain using both single and two-photon excitation. This article describes these approaches and presents a simple model that demonstrates key advantages of axially-extended illumination over point-scanning strategies for high-speed volumetric imaging, including longer integration times per voxel, improved photon efficiency and reduced photodamage.