For explaining why morphine can paradoxically cause pain, and showing that the mechanisms underlying pain hypersensitivity are distinct from those causing morphine tolerance.
Original research article: Ferrini F, Trang T, Mattioli TA, Laffray S, Del'Guidice T, Lorenzo LE, Castonguay A, Doyon N, Zhang W, Godin AG, Mohr D, Beggs S, Vandal K, Beaulieu JM, Cahill CM, Salter MW, De Koninck Y. Morphine hyperalgesia gated through microglia-mediated disruption of neuronal Cl⁻ homeostasis. Nat Neurosci. 2013 Feb;16(2):183-92. doi: 10.1038/nn.3295. Epub 2013 Jan 6.