Belying their name, simple cells are an eclectic bunch. For one thing, they keep the orderly map of the visual world that came from the retina, so nearby simple cells respond to similar positions in the world. For another, tens of channels of information from the retina have slammed into the simple cells that surround us. Thirty-plus channels for every location in visual space, for the middle, the left, the right, up and down, everywhere. So collections of simple cells bunched together are interested in different things about the same location in the world: some in edges at 90 degrees, some at
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