Today we know that there are dozens of different types of neurons in the neocortex, not six. Scientists still use the six-layer terminology. For example, one type of cell might be found in Layer 3 and another in Layer 5. Layer 1 is on the outermost surface of the neocortex closest to the skull, at the top of Cajal’s drawing. Layer 6 is closest to the center of the brain, farthest from the skull. It is important to keep in mind that the layers are only a rough guide to where a particular type of neuron might be found. It matters more what a neuron connects to and how it behaves. When you
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