The Role of Sensory Neurons
Billions of brain cells, or neurons, are formed throughout the first stages of fetal development and through birth. When an infant is born, the only part of the brain that is very developed, is the brain stem. This part of the brain controls functions such as; kicking, sleeping, rooting, crying and feeding. Right after birth, an infant's brain begins making over a trillion neuron connections, or synapses which are used to transmit information based on various life experiences. Stimulation through the senses of touch, hearing, seeing, smelling, and tasting directly affect the sensory neurons and help in establishing these connections. According to research, an infant's brain is producing 2-3 million synapses per second!
The more frequently the neuron connections are used, the more they retain information and the stronger they become. If some of the neural pathways are not used, they will end up dying out (this is called pruning). This is a necessary step in the brain development process for it prevents "overload" so to speak. Once these synapses gain strength and are noted by the brain that these are the pathways of important information, they become protected by a myelin sheath (a natural insulating material) that helps in sending messages to the brain even faster.
This process occurs mostly with the neurons and synapses that control a baby's sensory areas such as the eyes, ears, nose, mouth, and skin. Many of these "new" connections help infants to reach important milestones such as color vision, develop a pincer grasp, or strive for parent attachment.