Relative frequency and example voltage traces of primate neurons that do not fit into the classification of Type I, II, or III. Exploded portion of the pie chart shows the relative contribution of the different cell groups to describe the neurons classified as “other” (a). Example voltage traces of a neuron from each group: a RS cell without much Ih or IK(IR) (b), neurons with a large fAHP (c), neurons with large low-threshold calcium spikes (d), and neurons with a stutter firing pattern (e). Scale bar: 20 mv and 100 ms