<unk> s can be found in the primary visual cortex (V1), the secondary visual cortex (V2), and Brodmann area 19 (V3). Like a simple cell, a<unk>  will respond primarily to oriented edges and gratings, however it has a degree of spatial invariance. This means that its receptive field cannot be mapped into fixed excitatory and inhibitory zones. Rather, it will respond to patterns of light in a certain orientation within a large receptive field, regardless of the exact location. Some<unk> s respond optimally only to movement in a certain direction. These cells were discovered by Torsten Wiesel and David Hubel in the early 1960s. They refrained from reporting on the<unk> s in (Hubel 1959) because they did not feel that they understood them well enough at the time. In Hubel and Wiesel (1962), they reported that<unk> s were intermixed with simple cells and when excitatory and inhibitory regions could be established, the summation and mutual antagonism properties didn't hold. The difference between the receptive fields and the characteristics of simple and<unk> s is the hierarchical convergent nature of visual processing.<unk> s receive inputs from a number of simple cells. Their receptive field is therefore a summation and integration of the receptive fields of many input simple cells, although some input is directly received from the LGN. The manner through which simple cells are able to make up<unk> s is not fully understood. A simple addition of receptive fields would result in<unk> s manifesting observable, separate excitatory/inhibitory regions, which is not the case.
Complex cell
Clue cell
Stem cell
Buttock cell
Nurse cell
Aschoff cell
Blood cell
Brain cell