Advances in two photon scanning and scanless microscopy technologies for functional neural circuit imaging

Abstract

Recent years have seen substantial developments in technology for imaging neural circuits, raising the prospect of large scale imaging studies of neural populations involved in information processing, with the potential to lead to step changes in our understanding of brain function and dysfunction. In this article we will review some key recent advances: improved fluorophores for single cell resolution functional neuroimaging using a two photon microscope; improved approaches to the problem of scanning active circuits; and the prospect of scanless microscopes which overcome some of the bandwidth limitations of current imaging techniques. These advances in technology for experimental neuroscience have in themselves led to technical challenges, such as the need for the development of novel signal processing and data analysis tools in order to make the most of the new experimental tools. We review recent work in some active topics, such as region of interest segmentation algorithms capable of demixing overlapping signals, and new highly accurate algorithms for calcium transient detection. These advances motivate the development of new data analysis tools capable of dealing with spatial or spatiotemporal patterns of neural activity, that scale well with pattern size.

A Systematic Evaluation of Interneuron Morphology Representations for Cell Type Discrimination

“…The development of experimental methods for highthroughput single cell RNA sequencing (Zeisel et al 2018;Saunders et al 2018;Tasic et al 2018;Cao et al 2019) and large-scale functional imaging (Baden et al 2016;Pachitariu et al 2017;Schultz et al 2017) has led to a surge of interest in identifying the building blocks of the brain -the neural cell types (Zeng and Sanes 2017;Xi et al 2018). Both data modalities are analyzed with specialized quantitative tools (Stegle et al 2015;Stringer and Pachitariu 2019) and produce data sets amenable to statistical analysis such as cell type identification by clustering.…”

Quadratic Mutual Information estimation of mouse dLGN receptive fields reveals asymmetry between ON and OFF visual pathways

“…We finally remark that, although here, the QMI receptive field mapping method has been applied to an electrophysiological dataset, it is likely to have wider application. In particular, we expect it to find use in mapping sensory receptive fields through technology such as multiphoton calcium [30], [31] or voltage [32] imaging, and in additional characterisation domains such as mapping selectivity functions in spatial memory [33].…”

Implantable photonic neural probes for light-sheet fluorescence brain imaging

“…Confocal imaging improves the contrast by optical sectioning, and out-of-focus light is rejected using a pinhole; however, a laser beam must be scanned across each point of the tissue and this significantly slows the image acquisition rate [9]. Multiphoton microscopy is also inherently a point or line scanning method, but because it uses infrared excitation (which provides a longer optical attenuation length [5]), the imaging depth in brain tissue can be extended to ∼1 mm and the focus of the light beam can be rastered in three-dimensions to achieve volumetric imaging [5,[10][11][12].…”