One way to test changes in brain function is by using Event Related Potentials (ERPs). ERPs are electrical signals (brain waves) our brains give off immediately after receiving a stimulus from the outside world. They occur in fairly predictable patterns with slight variations depending on the individual brain. These variations, visualized in the figure above with the darkest red and blue areas showing the most intense electrical signals, can clue researchers into how brain function differs between individuals and groups, in this case musicians and bilinguals.
The ERP experiment performed here consisted of a go/nogo task that is frequently used to study brain activity when it is actively suppressing a specific behavior, also called inhibition. In this study, the authors asked research participants to sit in front of a computer while simple shapes appeared on screen, and they were to press a key when the shape was white—the most common-colored shape in the task—but not when purple, the least frequent color in the task. In other words, they responded to some stimuli (go) and inhibited their response to others (nogo). This is a similar task to playing music or speaking a second language because the brain has to identify relevant external sensory information, call on a set of learned rules about that information, and make a choice about what action to take.
The authors combined and compared correct responses to each stimulus type in control (non-musician, non-bilingual) groups, musician groups, and bilingual groups. The figure above compares the brainwaves of different groups over time using stimulus related brainwave components called N2, P2, and LP. As can be seen above, these peaks and valleys were significantly different between the groups in the nogo instances. The N2 wave is associated with the brain’s initial recognition of the meaning or significance of the stimulus and was strongest in the bilingual group. The P2 on the other hand, is associated with the early stages of putting a stimulus into a meaningful context as it relates to an associated behavior, and was strongest in the musician group. Finally, the authors note a wave called LP wave, which showed a prolonged monitoring response in the bilingual group. The authors believe this may mean bilinguals take more time to make sure their initial reaction is correct.
In other words, given a task that involved identifying a specific target and subsequently responding or not responding based on learned rules, these results suggest that musicians’ brains may be better at quickly assigning context and an appropriate response to information because they have a lot of practice turning visual and auditory stimuli into motor responses. Bilinguals, on the other hand, show a strong activation response to stimuli along with prolonged regulation of competing behaviors, likely because of their experience with suppressing the less relevant language in any given situation. Therefore, despite both musicianship and bilingual experiences improving brain function relative to controls, the aspects of brain function they improve are different. As games and activities for the purpose of “brain training” become popular, the researchers hope this work will help with testing the effectiveness of brain training.
Citation: Moreno S, Wodniecka Z, Tays W, Alain C, Bialystok E (2014) Inhibitory Control in Bilinguals and Musicians: Event Related Potential (ERP) Evidence for Experience-Specific Effects. PLoS ONE 9(4): e94169. doi:10.1371/journal.pone.0094169
Images are Figures 1 and 2 from the article.