Early brain development has a tremendous impact on the success of humans throughout their lives. During early development, neural circuit formation proceeds in a strictly regulated manner. In addition to genetic and epigenetic programs, recent studies using animal models have demonstrated that certain maternal bio-active agents are essential for normal neural development, with deficiencies adversely affecting offspring brain function and behavior. On the basis of these findings, we propose a new viewpoint: that maternal bio-active substances support the development of the fetal and neonatal brain, and the subsequent expression and maintenance of higher brain functions. We term these molecular-based biological conversations between mother and offspring "bio-communications". Based on findings obtained primarily from animal models, we review the effects of maternal substances on the neural developments and functions. Clarifying the regulatory mechanisms of "bio-communications" will help improve understanding of the mechanisms of human brain functioning and neural development. In addition, these findings will be applied to elucidate the mechanisms of developmental disorders and to explore new medical therapies to treat them.