Data from: Vertical exploration and dimensional modularity in mice

Exploration is a central component of animal behaviour studied extensively
in rodents. Previous tests of free exploration limited vertical movement
to rearing and jumping. Here we attach a wire mesh to the arena wall,
allowing vertical exploration. This provides an opportunity to study the
morphogenesis of behaviour along the vertical dimension, and examine the
context in which it is performed. In the current setup, the mice first use
the doorway as a point reference for establishing a borderline linear path
along the circumference of the arena floor, and then use this path as a
linear reference for performing horizontal forays towards the center
(incursions) and vertical forays on the wire mesh (ascents). Vertical
movement starts with rearing on the wall, and commences with straight
vertical ascents that increase in extent and complexity. The mice first
reach the top of the wall, then mill about within circumscribed horizontal
sections, and then progress horizontally for increasingly longer distances
on the upper edge of the wire mesh. Examination of the sequence of
borderline segments, incursions and ascents reveals dimensional
modularity: an initial series ("bout") of borderline segments
precedes alternating bouts of incursions and bouts of ascents, thus
exhibiting sustained attention to each dimension separately. The exhibited
separate growth in extent and in complexity of movement and the sustained
attention to each of the three dimensions disclose the mice's modular
perception of this environment and validate all three as natural kinds.