A Virtual Environment: Exploring the Brain Forest

Abstract

Abstract. Exploring the Brain Forest, a virtual environrnent currently in design, will present hierarchical views of the btain at several levels of scale from a global overview to immersion within its forest of neurons and glial cells. Participants are encouraged to enter, become immersed in, and wander within the most spatially complex structure known in nature. Exploring the Brain F orest is being designed as a 3D graphical model onto which will be mapped brain data sets drawn from microscopy of ral, monkey and human brain tissue mapped at the limit ofoptical resolution. In the cortex, for example, pyramidal neurons scaled up 50,000 times resemble giant Sitka spruce trees, while other neurons mimic hardwoods oftropical rain forests. This volumetric brain model will provide both an initial orientation and a portal into the virtual microscopy ofbrain structure. Methods for constructing the environment include creating a fínite element model of the human cortex and implanting this solíd model with synthetically-generated morphological models of neurons. Stochastic L-system models are used for this purpose. The imagery is sufficiently complex that its presentationin a virtual reality simulation requires several entwined display strategies to be successful. Two such strategies exploiting the limitations ofthe human visual system, gaze-contingent and scale-dependent geometric modeling, are employed to reduce the graphical complexity of the environment.