History and literature were Moruzzi's favorite subjects when he was growing up, but he chose to study medicine because Italy's economy was struggling at the time and he knew that he would always have job opportunities with a medical degree.

Pensa left to work in Pavia, but Moruzzi stayed behind, in part because he could not afford to move away from home but also because his interests had shifted from neuroanatomy to neurophysiology.

He then worked at the Neurophysiological Institute of Cambridge under Edgar Adrian, where the pair became known for recording discharges from single motor neurons in the pyramidal tracts.

[3] Once at Northwestern, Moruzzi met Horace Winchell Magoun and Donald B. Lindsley, and they worked to elucidate the neural processes responsible for wakefulness.

In a 1949 experiment with a cat, Moruzzi and Magoun proved that stimulation of a certain brain region (near the intersection of the pons and midbrain) created a state of alertness.