<P> Receptive fields of cells in the visual cortex are larger and have more - complex stimulus requirements than retinal ganglion cells or lateral geniculate nucleus cells . Hubel and Wiesel (e.g., Hubel, 1963; Hubel - Wiesel 1959) classified receptive fields of cells in the visual cortex into simple cells, complex cells, and hypercomplex cells . Simple cell receptive fields are elongated, for example with an excitatory central oval, and an inhibitory surrounding region, or approximately rectangular, with one long side being excitatory and the other being inhibitory . Images for these receptive fields need to have a particular orientation in order to excite the cell . For complex - cell receptive fields, a correctly oriented bar of light might need to move in a particular direction in order to excite the cell . For hypercomplex receptive fields, the bar might also need to be of a particular length . </P> <Table> Original Organization of Visual Processing Cells by Hubel and Wiesel <Tr> <Th> Cell Type </Th> <Th> Selectivity </Th> <Th> Location </Th> </Tr> <Tr> <Td> Simple </Td> <Td> orientation, position </Td> <Td> Brodmann area 17 </Td> </Tr> <Tr> <Td> Complex </Td> <Td> orientation, motion, direction </Td> <Td> Brodmann area 17 and 18 </Td> </Tr> <Tr> <Td> Hypercomplex </Td> <Td> orientation, motion, direction, length </Td> <Td> Brodmann areas 18 and 19 </Td> </Tr> </Table> <Tr> <Th> Cell Type </Th> <Th> Selectivity </Th> <Th> Location </Th> </Tr> <Tr> <Td> Simple </Td> <Td> orientation, position </Td> <Td> Brodmann area 17 </Td> </Tr>

Somatosensation collectively the receptive fields of one dorsal root ganglia are called