aphasia

Aphasia is the loss or weakening of the ability to use language after the brain is injured — usually after a stroke, a head injury, a tumor, or a slowly progressing disease. A person with aphasia may struggle to find words, scramble them, leave them out, or have trouble understanding what others say, even though their mouth, ears, and intelligence still work fine. Imagine knowing exactly what you want to say but the door between the thought and the words is jammed: the idea is there, yet it cannot get out cleanly.

Language in most people leans on a network of regions in the left side of the brain, and aphasia shows up differently depending on which part is damaged. When the front part (an area linked to Broca) is hurt, speech becomes slow and effortful — short, broken phrases — yet understanding stays fairly good; when a region farther back (linked to Wernicke) is hurt, speech flows easily but the words come out jumbled or empty of meaning, and understanding others becomes hard. Because the damage is to the language machinery and not to the muscles or the mind, many people with aphasia recover some ability with time and speech therapy, and they often understand far more than they can express.