Ramon cajal sketch cerebral cortex brain

The images are iconic to anyone who has dipped a toe in the vast and enigmatic pool of neuroscience: A delicate branching pattern emanates from and surrounds a small black splotch.

Varied line weights hint at the three-dimensional structure the drawing describes, reminiscent of a bare-branched tree in winter.

Ramon cajal sketch cerebral cortex brain

These are Spanish neuroanatomist Santiago Ramón y Cajal's drawings of neurons.

Over five decades of work, Cajal () created more than 2, drawings detailing the nervous system's architecture. Countless hours of close observation informed those drawings and helped him realize two fundamental truths of neuroanatomy.

First, he deduced that the brain was made up of many individual cells, called neurons, rather than a spider web-like structure of fused cells (the view of many of his contemporaries). Second, the electrical signals those cells generate flow through neurons in one direc