This is a dated academic article regarding the association of brain activity and native language. Many linguists have promoted the idea beyond the research findings in such a manner that understanding may be increased if native language or mother tongue is employed.
Proverbio AM, Adorni R, Zani A. 2009. ‘Inferring native language from early bio-electrical activity.’ Biological Psychology Jan, 80(1):52-63.
Another review (a strong one) albeit indirectly.
I qoute from the Fountain Magazine:
A study was carried out on fifteen Italian interpreters who were working for the European Union and translating in English and Italian. The interpreters were all extremely fluent in English. The study revealed surprising differences in brain activity when the subjects were shown words in their native language versus in other languages they spoke. About 170 milliseconds after a word was shown, the researchers recorded a peak in electrical activity in the left side of the brain, in an area that recognizes letters as part of words before their meaning is interpreted. These brain waves had much higher amplitude when the word was in Italian, the language the interpreters had learned before age five. “The findings show how differently the brain absorbs and recalls languages learned in early childhood and later in life,” said Alice Mado Proverbio, a professor of cognitive electrophysiology at the Milano-Bicocca University in Milan. Proverbio attributed the differences to the fact that the brain absorbs the mother tongue at a time when it is also storing early visual, acoustic, emotional and other nonlinguistic knowledge. This means that the native language triggers a series of associations within the brain that show up as increased electrical activity. “Our mother tongue is the language we use to think, dream and feel emotion,” Proverbio said.