The Impact of Developmental and Genetic Influences on Neural Circuits

BACKGROUND: Neural circuits form the basis for brain function and behavior. However, solely focusing on adult brains can sometimes overlook prior events that may have shaped this anatomy. These other perspectives can provide further insight into brain circuit organization. SUMMARY: To support this suggestion, specific examples of developmental and genetic events are presented that might not be appreciated if only adult brains were investigated. Examples include the following. One is the origin of nuclei from the same developmental field that divides into two major nuclei. Each subdivision has neurons with different dendritic arbors and different input and output circuits. The other is new circuit formation that is produced in three ways. One is the result of peripheral sensory receptor reduction. Another is the consequence of genetic mutation. The third is due to axonal pruning or perinatal injury. KEY MESSAGE: In certain instances, developmental and genetic features provide additional perspectives to better understand how circuit formation in the brains of adult animals came to be.