The Two Prefrontal Streams: Evidence for Homology Across Species

Excerpt

The prefrontal cortex (PFC) plays a critical role in human cognition, but the precise mechanisms by which its circuitry accomplishes its proposed functions are unclear. Nonhuman animals are indispensable in revealing such mechanisms, as the ability to monitor and manipulate their circuitry provides necessary insights. A major impediment to linking the growing progress in animal research to insights for human cognition and applications to human health is the lack of consensus on how the PFC is homologous across species. In this perspective, we follow the classification of human PFC into medial and lateral streams, with the medial being primarily evaluative and the lateral being executive. Based on anatomy, physiology and function, we advance the proposal that the rodent medial prefrontal cortex contains elements of both streams, with functional parallels between primate ventromedial and dorsolateral PFC with rodent infralimbic and prelimbic areas, respectively. To support this argument, we highlight the granular nature of the prelimbic cortex in Tupaia belangeri, a basal primate whose PFC macrostructure is rodent-like. Our perspective may help provide additional input to the debate on PFC homology and lead to new testable hypotheses.