This diagram shows correlation between connectivity and distance of neurons in the human cortex. There are approximately 100,000 neurons in a square millimeter of cortex, as illustrated in the center box. The red gradation shows neuronal connectivity, with dark red indicating denser connectivity through synapses. While half of the synapses connect to neurons close to them, the other half connect with distant neurons, as so illustrated in the boxed area on the far left of this diagram. The differences in connectivity and distance between neurons require whole brain simulation in order to understand brain function.
