How far does one click spread? Drop the excitation below about 0.8 and a click dies out after a flash or two; raise it past 0.9 and the same click cascades across the tissue. The counter below measures it.
The shape is a stylized point cloud, not anatomy. It is a procedural surface with two hemispheres, a cerebellum, and a stem, drawn in the site's glyph-and-dot language; no region boundary here is anatomically exact.
Each of the 3,600 cells is the leaky integrate-and-fire unit from lesson 2: charge leaks away, and a cell fires once it is pushed past threshold. The connections are simply each cell's 6 nearest neighbors in space, not real connectomics. The excitation slider scales how strongly a spike drives its neighbors.
Reference for the unit model: Gerstner et al., Neuronal Dynamics, section 1.3.