What is included in the composition of brain tissue categorized as white matter?

White matter in the brain is primarily composed of myelinated nerve fibers that connect different regions of gray matter across the central nervous system. These nerve fibers are crucial for communication between various brain regions, enabling the integration and processing of information. The myelin sheath, which surrounds these fibers, gives white matter its characteristic color and enhances the speed and efficiency of electrical signal transmission.

The presence of nerve fibers linking neurons into functional circuits is essential for the overall functioning of the brain, as they facilitate rapid communication and coordination between different areas involved in cognitive, sensory, and motor processes. This connectivity helps to form the neural pathways that underpin various functions, including memory, perception, and decision-making.

In contrast, the other options, while essential to brain function, do not define the composition of white matter. Cell bodies of neurons, synaptic connections, and structures of gray matter are all components related to gray matter—the area of the brain where processing and signaling occur. Understanding these distinctions is vital for grasping the anatomy and physiology of the central nervous system.