"Some investigators contend that EEG patterns denoting wakefulness indicate when consciousness is first possible. Wakefulness is a state of arousal mediated by the brainstem and thalamus in communication with the cortex. In preterm neonates, the earliest EEG pattern representing wakefulness appears around 30 weeks’ PCA. However, wakefulness alone is insufficient to establish consciousness, as unconscious patients in a persistent vegetative state may also have wakeful EEGs."