It had been thought that new brain cells grew only in young children, and that thereafter every bump on the head or glass of wine led to a loss of intelligence.
One of the simplest procedures, with a relatively short recovery time, is called an exostectomy, in which the bump on the head of the first metatarsal is thinned or shaved off with a surgical saw.
If you slip in a mud puddle, destroying your iPhone (along with any locally stored encryption keys) and forgetting your passwords as a result of the bump on the head, can you still recover your data?