Figure 10.

Hierarchy of action representation in the rat. A, Strategic representations such as spatial and egocentric are encoded in PL-IL. OFC encodes paths and possibly—in the combined activity of path-selective cells—tasks. Memory structures such as the hippocampus encode contextual information, whereas the dorsal striatum encodes stimulus–response pairings. Sensory cortices encode stimuli, whereas the motor cortex encodes responses. Higher levels of the hierarchy are created by combining the representations of lower levels. As the position in the hierarchy increases, the representations become more abstract (adapted from Rich and Shapiro, 2009). B, PL-IL, OFC, and hippocampus represent different levels of abstraction along rewarded paths. PL-IL represents a path only in the context of a particular strategy such as spatial. Ensembles in OFC are active continuously along rewarded paths. Individual hippocampal cells represent the component locations along the path. Interactions between the brain regions integrate these representations to guide behavior.