Encodes areas, zones, and bounded spatial regions.
What It Does
Space.Region neurons activate on bounded spatial areas: territories ('Eastern Europe', 'the tropical zone'), domains ('the private sector', 'the public sphere'), areas of effect ('the blast radius', 'the coverage area'), and conceptual regions ('the gray area', 'the danger zone'). They encode space as a defined domain with extent, distinct from a point (Position) or a trajectory (Direction).
How It Behaves
Region neurons show a disproportionate middle-layer concentration, where spatial extent is being integrated with semantic content. They are particularly active in scientific and technical contexts where domains are precisely defined, and in political or geographic contexts where territorial boundaries matter. Region neurons interact with Identity.Place neurons (named regions) and Space.Boundary neurons (the edges of regions).
Research Example
In Llama 3.1 8B, Space.Region neurons activate on 'the area of the brain responsible for language processing' — an anatomical region defined by function rather than geography. The same Region neuron sub-type handles both physical geographic regions and functionally-defined domains, reflecting the model's generalization of spatial region concepts across domains.