Indeed, studies of both POMC and NPY/AgRP neurons from ob/ob mice reveal that they undergo extensive synaptic plasticity under conditions of obesity; with the former receiving significantly more inhibitory inputs concomitant with a reduction in excitatory inputs, and the latter having appreciably more excitatory inputs and fewer inhibitory ones impinging upon them [136]. This evidence concerns the gene NPY and obesity due to melanocortin 4 receptor deficiency.