Because the spinal cord is connected with the white matter of the brain, the white matter mainly plays a conductive role, and the excitement is transmitted from the whole body to the central nervous system of the spinal cord, through the outer white matter of the spinal cord to the inner white matter of the brain, and then to various regions of the cerebral cortex to generate excitement, and then back to the whole body to form networks and circuits. The gray matter of the spinal cord also comes from the outer layer of white matter, and then comes out. Anyway, this layout is the most reasonable.

The gray matter of cerebral cortex plays a leading role, and the expansion area of the outer layer is larger, which is more conducive to brain development.

Moreover, the white matter of the brain is wrapped in gray matter, so the contact area is large and the transmission efficiency is fast ~

It should be like this. I guessed = =