Giuseppe Moruzzi’s midpontine pretrigeminal preparation and its continuing importance for neuroscience

Abstract

More than 50 years ago Giuseppe Moruzzi and his collaborators reported that cats with a complete transection of the pons in front of the origin of the trigeminal nerve were almost continuously awake, suggesting that the brain had been separated by sleep-inducing structures in the brainstem behind the section. Several pieces of experimental evidence were subsequently obtained to show that the isolated brain of midpontine pretrigeminal cats was capable of conscious awareness, learning and sensitivity to rewarding brain stimulation. The current interest of those data for clinical neurology is that there are striking resemblances between the midpontine pretrigeminal preparation and the human locked-in syndrome, in which the patients are fully conscious but unable to move except for palpebral or ocular movements. Here I present the basic evidence for assuming that the midpontine pretrigeminal cat may serve as an at least partial model for the locked-in syndrome and suggest that it may provide useful insights into the neural mechanisms of consciousness in absence of behavior.