Figure 5.1 Connecting genes to brain to cognition in the autisms. Genes interact with environmental and stochastic factors during fetal and post-natal development, affecting the cerebral structure that underlies all human behavior and cognition. This structure is not static, but dynamic, and ranges in scale from the highly plastic chemical, molecular, and microscopic structures to neural circuits and the visible gross anatomy. The understanding of behavior and cognition is therefore rooted in an understanding of this dynamic structure, which itself is critically dependent on cognitive function (environment) for its normal development; hence the bi-directional arrow connecting cerebral structure to cognitive function. From a developmental perspective, what one may observe at a given epoch likely reflects an initial genetic insult modified by alterations in developmental trajectory caused by alterations in experience.