Histogram of the receptive field size of nociceptive specific (A), nociceptive nonspecific (B), and tactile (C) PoT neurons. Abscissa, Size of receptive field; VS, very small = one digit or one vibrissa; S, small = one paw, one part of the face or the tail; M, medium = two to four parts of the body; ordinate, percentage of neurons in each class; black, receptive fields exclusively contralateral; gray, receptive fields bilateral with contralateral predominance.