  First, older children — even those who have not succeeded in  learning language previously — can substantially recover from  left hemisphere trauma occurring well after the supposed closure of  the ‘sensitive’ or ‘critical’ period; in  effect, they learn language from scratch as adolescents.  Vargha-Khadem et al. 1997, for instance, report the case of Alex,  who failed to speak at all during childhood and whose receptive  language was at age 3-4 level at age 9. After his left cortex was  removed at age 9, Alex suddenly began to learn language with gusto,  and by age 15, his skills were those of an 8-10 year old.