What aspects of brain development underlie tremendous gains in language, thinking and motor control in early childhood?

Cerebellum, Hippocampus, Corpus Callosum and Reticular Formation are the aspects of brain development  that leads to  tremendous gains in language, thinking and motor control in early childhood

Explanation:

The cerebellum of brain is basically involved in balancing and controlling body movements. Thinking is processed in human being due to the connection between cortex and cerebellum. The motor and cognitive efficiencies such as memory, language, perception, understanding, etc.  in a child are developed due to this cortex and cerebellum association. Hippocampus with in the brain helps a child to memorize, perceive images and understand the spatial context of world in early childhood.  

Reticular Formation causes consciousness and alertness in a child by generating synapses and myelinated starting from childhood to the adulthood.  

Corpus Callosum integrates the simultaneous movement of left and right side body parts as they are controlled by left and right hemisphere

Thus, Cerebellum, Hippocampus, Corpus Callosum and Reticular Formation are the aspects of brain development  that leads to  tremendous gains in language, thinking and motor control in early childhood