What is the myelin sheath and how does it relate to the cephalocaudal and proximodistal directions of motor skill development? Describe the sequence of motor milestones related to each direction.

Question

What will be an ideal response?

Answer 1

The myelin sheath is a fatty coating that wraps around the nerves to ensure that the chemical messages sent between neurons are delivered efficiently. When babies are born, just as the synaptic connections are not complete, so too the myelin sheath does not yet cover all of the nerves in the nervous system. The process of producing synaptic connections, pruning away those that are not being used, and myelinating the connections that are left will continue throughout childhood and adolescence. Myelination begins in the lower centers at the base of the brain and continues through the higher centers of the cortex (Deoni et al., 2011). As researchers learn more about the normal progression of myelination, they are also likely to find evidence of abnormal processes that may contribute to such disorders as autism and schizophrenia (Deoni et al., 2011). There is also evidence that myelination is affected by our experiences. Bengtsson et al. (2005) compared brain development in children who spent long hours practicing piano to that in children who did not play piano. Their evidence indicates that the extra stimulation that certain neurons experience when children are practicing results in more myelination of those neurons, including those in the corpus callosum, which connect the two hemispheres of the brain. The corpus callosum is involved in the ability to coordinate movements of your two hands at the same time. In this study, children who played piano had increased brain efficiency, and this increased ability continued into adolescence.
Answer can vary for proximodistal and cephalocaudal growth.