  The brain in conjunction with the body is able to adapt to new environments
and perform multiple behaviors through reuse of neural resources and transfer
of existing behavioral traits. Although mechanisms that underlie this ability
are not well understood, they are largely attributed to neuromodulation. In
this work, we demonstrate that an agent can be multifunctional using the same
sensory and motor systems across behaviors, in the absence of modulatory
mechanisms. Further, we lay out the different levels at which neural reuse can
occur through a dynamical filtering of the brain-body-environment system's
operation: structural network, autonomous dynamics, and transient dynamics.
Notably, transient dynamics reuse could only be explained by studying the
brain-body-environment system as a whole and not just the brain. The
multifunctional agent we present here demonstrates neural reuse at all three
levels.
