EEG: Code Switching & The Language You Think In

In 2004 a team of scientists under the lead of Alice Mado Proverbio, professor of cognitive electrophysiology at the Milano-Bicocca University in Milan, analysed the brain activity of fifteen subjects via EEG while they were shown sentences in their native and secondary language (L2). The subjects were interpreters for the European Union and fluent in English. They were shown sentences which "could be entirely in Italian or in English (unmixed); alternatively, the body of the sentence could be in English and the final word in Italian or vice versa (mixed)." (Proverbio 2004) The objective was to determine "[...] neural mechanisms subserving code switching [...]." (ibid.) They monitored an alteration in the brain waves as the participants where code switching.

This sounds quite interesting. Unfortunately, from a linguistic point of view, you can't compare two different languages this way I think. The slightly higher amplitude can rise due to the different morphology, syntax and phonology. Italian, as a Romance language, focus much more on grammatical morphemes than English.
Take the phonology: The IPA notes for Standard English (RP) 24 consonants, 21 vowels (Sauer 1990) compared to Standard Italian with 46 consonants (short and long consonants) and 27 vowels (Rogers & d'Arcangeli 2004).
Take the morphology: "Nouns in Italian have gender (masculine or feminine, but no neuter), and number (singular or plural). The gender and number is always shown by the leading article (definite or indefinite), and usually by the final vowel. [...] Adjectives, like nouns, have two genders and two numbers. Italian verb infinitives have one of three endings, either -are, -ere, or -ire. (Wikipedia) In English we have the third person pronouns, the Saxon genitive and only 8 possible inflection forms for verbs.
In contrast to the rudimentary English verb conjugation system the Italian language has a distinctive system derived from Latin. Furthermore, the lexicon from L1 may be stored deeper in the left hemisphere than the lexicon from L2.

Sentences like:

(A) Occorre impedire l’uso fraudolento delle carte di CREDITO.

in comparison to

(B) The fraudulent use of CREDIT cards must be prevented.

may not be equal and produce different results.

Earlier this year another paper of Proverbio (et al.) was published in Biological Psychology which is about the difference between native language, secondary and even tertiary language (L2, L3) usage and their representation in the brain. The brain activity was recognisably higher when they were shown words from their native language.

"Proverbio attributed the differences to the fact the brain absorbs the mother tongue at a time when it is also storing early visual, acoustic, emotional and other nonlinguistic knowledge." (MSNBC)

Unfortunately, this article is not available for my university and therefore out of reach. I doubt whether an EEG could so easily find the difference between first and second language. You can't easily compare an Italic language with a Germanic language that way; they were separated from their Indo-European roots 2000 years ago. At least you have to consider the difference between morphology, phonology, semantics and syntax. Semantics I havn't mentioned yet. Italian words have sometimes 'more or less meanings' attached they are not equal to e.g. German words.

Lingformant
MSNBC
Proverbio, M. Alice (et al.). Language switching mechanisms in simultaneous interpreters: an ERP study. In: Neuropsychologia 42 (12). 2004: 1636-1656.
Proverbio, M. Alice (et al.). Inferring native language from early bio-electrical activity. In: Biological Psychology. 2008.
Rogers & d'Arcangeli. Vowels of Italian. 2004.
Sauer, Walter. A Drillbook of English Phonetics. 1990.


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Note:
I changed this article due to Ms. Proverbio's correction in the comments. The article on MSNBC was misleading since they mixed the content of the 2004 paper with the paper from 2008.