A–E, F–J, The tuning functions of example neurons from C5 and C6. The neurons in these clusters were orientation and SF selective, but one characteristic that separated them from the other two clusters was their insensitivity to contrast. They are separated from each other by their TF tuning, neurons in C5 were bandpass, and those in C6 were low pass. K–O, P–T, Neurons from the smaller clusters where most of the neurons were weakly selective for orientation and relatively low pass in SF (f1/f0 1.3 and 1.5, respectively). The other details are as for Figure 1.