New insights on the olfactory lobe of decapod crustaceans.

Studies on the crustacean nervous system have been responsible for advances in neuroscience and continue to play an important role in comparative neurobiology. The organization of crustacean brains provides clues about their phylogeny and might also offer some hints regarding their lifestyles. In this study, we compared the organization of specific brain regions of three species of marine shrimp with two species of freshwater prawns, making possible the identification of a pathway issuing from the periphery and cluster 9, which was not previously identified in freshwater prawns and shrimp. Although the brains of the species studied show the same general organization of other crustaceans, variations in the structural organization of the olfactory lobe, evidenced by different immuno-markers, were observed between shrimp species and prawns. In contrast to shrimp, the more well-defined organization of the olfactory lobe in freshwater prawns might reflect greater integration in the processing of olfactory information. Also, in freshwater prawns we described fibers organized as a tract similar to the deutocerebral commissure.