The subiculum: cell-type-specific composition, computation, and function

The hippocampus is a key brain region for understanding the neurobiological mechanisms of learning, memory, and cognition. The subiculum, which provides the predominant form of hippocampal output via excitatory neurons, offers an advantageous perspective with which to understand these mechanisms. In this review, focusing on recent rodent research, we summarize and integrate results on subiculum excitatory neurons across molecular, cellular, circuit, and functional properties. This collective work converges upon discrete excitatory neuron subtypes coherently represented across modalities, with these subtypes occupying distinct spatial subdomains within the subiculum. This subtype framework helps contextualize existing findings on hippocampal processing, illustrates the possibility of spatially restricted parallel hippocampal outputs, and provides a biological roadmap for future experiments pursuing the mechanisms of hippocampal function.