This coronal section image shows a heart-shaped population of oxytocin neurons (red) residing in the caudal paraventricular nucleus of the hypothalamus. With electrophysiological recording and biocytin immunostaining, two canonical subpopulations are easily identified: Magnocellular neurons (magenta), with rectification and larger soma, and Parvocellular neurons (green), with narrower AP and more complex morphology. But the morphological and electrophysiological properties of these subtypes changes along rostral-caudal axis of the paraventricular nucleus, creating far more than two subtypes. For more information, see the article by Chen et al. (pages 2885–2904). Cover image: Lei Xiao.