VIOLA - A multi-purpose and web-based visualization tool for neuronal-network simulation output

Abstract

Neuronal network models and corresponding computer simulations areinvaluable tools to aid the interpretation of the relationship betweenneuron properties, connectivity and measured activity in corticaltissue. Spatiotemporal patterns of activity propagating across thecortical surface as observed experimentally can for example be describedby neuronal network models with layered geometry and distance-dependentconnectivity. In order to cover the surface area captured by today'sexperimental techniques and to achieve sufficient self-consistency,such models contain millions of nerve cells. The interpretation ofthe resulting stream of multi-modal and multi-dimensional simulationdata calls for integrating interactive visualization steps into existingsimulation-analysis workflows. Here, we present a set of interactivevisualization concepts called views for the visual analysis of activitydata in topological network models, and a corresponding referenceimplementation VIOLA (VIsualization Of Layer Activity). The softwareis a lightweight, open-source, web-based and platform-independentapplication combining and adapting modern interactive visualizationparadigms, such as coordinated multiple views, for massively parallelneurophysiological data. For a use-case demonstration we considerspiking activity data of a two-population, layered point-neuron networkmodel incorporating distance-dependent connectivity subject to a spatiallyconfined excitation originating from an external population. Withthe multiple coordinated views, an explorative and qualitative assessmentof the spatiotemporal features of neuronal activity can be performedupfront of a detailed quantitative data analysis of specific aspectsof the data. Interactive multi-view analysis therefore assists existingdata analysis workflows. Furthermore, ongoing efforts including theEuropean Human Brain Project aim at providing online user portalsfor integrated model development, simulation, analysis and provenancetracking, wherein interactive visual analysis tools are one component.Browser-compatible, web-technology based solutions are therefore required.Within this scope, with VIOLA we provide a first prototype