Abstract
Recent discoveries that astrocytes exert proactive regulatory effects on neural information processing and that they are deeply involved in normal brain development and disease pathology have stimulated broad interest in understanding astrocyte functional roles in brain circuit. Measuring astrocyte functional status is now technically feasible, due to recent advances in modern microscopy and ultrasensitive cell-type specific genetically encoded Ca2+ indicators for chronic imaging. However, there is a big gap between the capability of generating large dataset via calcium imaging and the availability of sophisticated analytical tools for decoding the astrocyte function. Current practice is essentially manual, which not only limits analysis throughput but also risks introducing bias and missing important information latent in complex, dynamic big data. Here, we report a suite of computational tools, called Functional AStrocyte Phenotyping (FASP), for automatically quantifying the functional status of astrocytes. Considering the complex nature of Ca2+ signaling in astrocytes and low signal to noise ratio, FASP is designed with data-driven and probabilistic principles, to flexibly account for various patterns and to perform robustly with noisy data. In particular, FASP explicitly models signal propagation, which rules out the applicability of tools designed for other types of data. We demonstrate the effectiveness of FASP using extensive synthetic and real data sets. The findings by FASP were verified by manual inspection. FASP also detected signals that were missed by purely manual analysis but could be confirmed by more careful manual examination under the guidance of automatic analysis. All algorithms and the analysis pipeline are packaged into a plugin for Fiji (ImageJ), with the source code freely available online at https://github.com/VTcbil/FASP.
Highlights
Astrocytes, which constitute nearly half the volume of the adult human brain, have long been considered to play only passive roles in the central nervous system, such as supplying trophic factors, maintaining ion homeostasis, and serving as an inert scaffold
We evaluated Functional AStrocyte Phenotyping (FASP) on both synthetic data simulating Ca2+ signaling and real data of in vitro human astrocyte induced pluripotent stem cells
We model the fluorescence microscopy imaging data of astrocyte Ca2+ dynamics Y[i, j, t] consisting of
Summary
Astrocytes, which constitute nearly half the volume of the adult human brain, have long been considered to play only passive roles in the central nervous system, such as supplying trophic factors, maintaining ion homeostasis, and serving as an inert scaffold. Active roles in regulating various aspects of neuronal function have been identified. Astrocytes interact with synapses through release of soluble factors driven by intracellular Ca2+ elevations (Agulhon et al, 2008; Haustein et al, 2014) and, as a result, the Ca2+ dynamics are the best established correlates of the excitatory state and functional readout of astrocytes. With the convergence of recent advances in both modern microscopy and ultrasensitive cell-type specific genetic encoded calcium indicators (GECI; Knöpfel and Boyden, 2012; Broussard et al, 2014), it is possible to conduct chronic optical imaging to record activities of a large number of astrocytes with high spatial and temporal resolution (Srinivasan et al, 2015), resulting in overwhelmingly large data sets and making manual analysis prohibitive. The detailed definition of FIU and characteristic curve is referred to Section Problem Statement and Formulation
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
