Final answer:
Phineas Gage suffered a severe brain injury when an iron rod impaled his prefrontal cortex. This caused a change in his personality, making him irritable, temperamental, and lazy. However, he was still able to function as a stagecoach driver, suggesting that the brain can recover from such trauma.
Step-by-step explanation:
Phineas Gage, a railroad worker, suffered a severe brain injury when an iron rod impaled his prefrontal cortex. After the accident, his personality changed, with him becoming irritable, temperamental, and lazy. This suggests that the frontal lobe, which plays a role in personality and behavior, was affected by the injury. However, Gage was able to function as a stagecoach driver, indicating that the brain has the ability to recover from major trauma.