Key study of neuroplasticity: Brain damage and language (Tierney et al. 2001)

You might have already read about Tierney et al.’s 2001 case study in the Pamoja textbook. However, many students’ explanations of this study and how it demonstrates neuroplasticity have key details missing.

To recap, this case study was conducted on a 37-year-old male patient they referred to as M.A. While participating in a language study that involved having your brain scanned with MRI, researchers noticed that M.A had a lesion in the left hemisphere of the brain. This area of the brain is responsible for our speech and language. The lesion most probably developed when he was two years old and he suffered from encephalitis (an uncommon but serious condition in which there is swelling in the brain).

It’s logical to assume that if the language areas of the brain were damaged before M.A could learn to talk or read fluently, then he would suffer from speech and language problems. However, this was not the case and M.A’s language skills had developed normally like other kids. In fact, he was bilingual – he spoke English and American sign language (ASL) because both of his parents had severe hearing problems. He used ASL at home and spoke English normally with other people.

The researchers hypothesized that this could be because other areas of M.A.’s brain had taken over the function of speech production to compensate for the damaged speech areas in the left hemisphere. To test this, M.A. was compared with 12 bilingual (English and ASL) participants. PET scans were used when the participants were participating in speech tasks. The speech tasks involved the participants simply recounting an event or a series of events in detail.

One key finding from the study is the comparison of brain activity between MA and the control subjects. M.A.’s right hemisphere was more active when talking about events in both spoken English and sign language. The controls, on the other hand, all had activation in the same areas of the left hemisphere of the brain.

Article by Travis Dixon