A historical perspective on the insect central complex: Anatomy, development, and function

The central complex (CX), a remarkable brain region at the core of insect behaviors, has been the subject of extensive research for decades. In this review, we offer a comprehensive historical perspective on the anatomy, development, and function of the CX. The CX consists of discrete and highly structured neuropils found at the center of the brain, and conserved across insects and arthropods. The developmental processes that shape it are themselves conserved across all panarthropods. In early research, the CX had been shown to receive visual information and control motor function. Using increasingly advanced methods throughout the years, it has become clear that the CX is involved in high-level behavioral control, including multimodal sensory cue integration as well as learning and memory. Its numerical simplicity presents a rare opportunity to study structure-function relationships in small brains, gain insights into evolutionary neurobiology, and develop novel neuromorphic technologies inspired by insect brains. Since the CX is a highly conserved brain region that controls a multitude of complex behaviors, it is uniquely suited to gain a detailed understanding of the computations required for these processes at the level of neural circuits.