High-throughput Analysis of Synaptic Activity in Electrically Stimulated Neuronal Cultures.

Synaptic dysfunction is a hallmark of various neurodegenerative and neurodevelopmental disorders. To interrogate synapse function in a systematic manner, we have established an automated high-throughput imaging pipeline based on fluorescence microscopy acquisition and image analysis of electrically stimulated synaptic transmission in neuronal cultures. Identification and measurement of synaptic signal fluctuations is achieved by means of an image analysis algorithm based on singular value decomposition. By exploiting the synchronicity of the evoked responses, the algorithm allows disentangling distinct temporally correlated patterns of firing synapse populations or cell types that are present in the same recording. We demonstrate the performance of the analysis with a pilot compound screen and show that the multiparametric readout allows classifying treatments by their spatiotemporal fingerprint. The image analysis and visualization software has been made publicly available on Github ( https://www.github.com/S3Toolbox ). The streamlined automation of multi-well image acquisition, electrical stimulation, analysis, and meta-data warehousing facilitates large-scale synapse-oriented screens and, in doing so, it will accelerate the drug discovery process.

A robust simulator for physiologically structured population models.

A framework to simulate physiologically structured population (PSP) models on high performance compute (HPC) infrastructure is built. Based on the model of a single cell, billions of cells can be simulated in an efficient way, allowing fast simulation of the interaction of an entire organ with other body parts. Trough combination of three state-of-the-art algorithms, the simulation time is decreased with multiple orders of magnitude. First: PSP modelling exploits the fact that a lot of the cells act the same at the same time which results in multiple orders of magnitude speed-up. Secondly, speed-up is achieved by using an unconditionally stable, partial differential equation solver which allows to trade speed for precision and allows big time stepping. Third speed-up is due to the fact that the framework is designed with HPC cluster use in mind. The PSP simulator is mathematically derived to have maximal stability.Simulation results are validated and simulation speed and accuracy are measured.

Image-Based Profiling of Synaptic Connectivity in Primary Neuronal Cell Culture.

Neurological disorders display a broad spectrum of clinical manifestations. Yet, at the cellular level, virtually all these diseases converge into a common phenotype of dysregulated synaptic connectivity. In dementia, synapse dysfunction precedes neurodegeneration and cognitive impairment by several years, making the synapse a crucial entry point for the development of diagnostic and therapeutic strategies. Whereas high-resolution imaging and biochemical fractionations yield detailed insight into the molecular composition of the synapse, standardized assays are required to quickly gauge synaptic connectivity across large populations of cells under a variety of experimental conditions. Such screening capabilities have now become widely accessible with the advent of high-throughput, high-content microscopy. In this review, we discuss how microscopy-based approaches can be used to extract quantitative information about synaptic connectivity in primary neurons with deep coverage. We elaborate on microscopic readouts that may serve as a proxy for morphofunctional connectivity and we critically analyze their merits and limitations. Finally, we allude to the potential of alternative culture paradigms and integrative approaches to enable comprehensive profiling of synaptic connectivity.