In this paper, we suggest that cortical anatomy recapitulates the temporal
hierarchy that is inherent in the dynamics of environmental states. Many aspects
of brain function can be understood in terms of a hierarchy of temporal scales
at which representations of the environment evolve. The lowest level of this
hierarchy corresponds to fast fluctuations associated with sensory processing,
whereas the highest levels encode slow contextual changes in the environment,
under which faster representations unfold. First, we describe a mathematical
model that exploits the temporal structure of fast sensory input to track the
slower trajectories of their underlying causes. This model of sensory encoding
or perceptual inference establishes a proof of concept that slowly changing
neuronal states can encode the paths or trajectories of faster sensory states.
We then review empirical evidence that suggests that a temporal hierarchy is
recapitulated in the macroscopic organization of the cortex. This
anatomic-temporal hierarchy provides a comprehensive framework for understanding
cortical function: the specific time-scale that engages a cortical area can be
inferred by its location along a rostro-caudal gradient, which reflects the
anatomical distance from primary sensory areas. This is most evident in the
prefrontal cortex, where complex functions can be explained as operations on
representations of the environment that change slowly. The framework provides
predictions about, and principled constraints on, cortical
structure–function relationships, which can be tested by manipulating
the time-scales of sensory input