Underneath the gray matter of the cortex lies white matter, made up largely of myelinated nerve fibers running to and from the ... The entire assemblage is surrounded by a sheath of glial cells. Each mossy fiber sends collateral branches to several ... la emoción y la conducta" [The role of the cerebellum in the regulation of affection, emotion and behavior]. Revista de ... He speculated that the cerebellum was the source of motor nerves. Further significant developments did not come until the ...