Generation of neural sentences is not confined to the hippocampal system. In the medial prefrontal cortex of the rat, neuronal sequences reliably differentiate between right and left trajectories in the maze prior to making a choice, with individual neurons active only for a short duration (Figure 4B; Baeg et al., 2003; Fujisawa et al., 2008). In summary, in contrast to the olfactory network and the birdsong system, cortical circuits can produce multitudes of unfolding assembly sequences in two different ways: either by responding to environmental/idiothetic stimuli, when such inputs are available, or generating them internally.
