Answer:
Myelin (also called Myelin Sheath).
Explanation:
This sheath is actually formed by special cells called Shwann Cells, that are wrapped around the axon. These membranous layers of these cells are made up of whitish fatty material. The myelin sheet also increase the speed at which impulses travel along an axon. All these explains how help the brain and other parts to speed neurotransmission and aid better communication.