Brain Region for Estimating Quantities Finally Mapped

You might call numerosity humans' sixth sense. This number sense gives us the ability to visually discern quantity, such as how many peaches are resting in a bowl or how many marbles are scattered across the floor. Like seeing or hearing, it's an evolutionary part of human and animal brains. Now researchers have shown that, like our other basic senses, numerosity depends on the organization and close proximity of very particular neurons. Scientists have long known that the brain's primary senses, such as sight and smell, lie in clusters of neurons in the sensory cortex. And these have been mapped to identify how and where the neurons for these sensory organs are organized in the brain. Such topographic maps have also been established for numerosity in macaques. Scientists figured that human numerosity, too, relied on specific neuron organization. They just hadn't been able to find it, until now. Benjamin Harvey ...