Discerning the functional networks behind processing of music and speech through human vocalizations
Musicality refers to specific biological traits that allow us to perceive, generate and enjoy music. These abilities can be studied at different organizational levels (e.g., behavioural, physiological, evolutionary), and all of them reflect that music and speech processing are two different cognitive domains. Previous research has shown evidence of this functional divergence in auditory cortical regions in the superior temporal gyrus (such as the planum polare), showing increased activity upon listening to music, as compared to other complex acoustic signals. Here, we examine brain activity underlying vocal music and speech perception, while we compare musicians and non-musicians. We designed a stimulation paradigm using the same voice to produce spoken sentences, hummed melodies, and sung sentences; the same sentences were used in speech and song categories, and the same melodies were used in the musical categories (song and hum). Participants listened to this paradigm while we acquired functional magnetic resonance images (fMRI). Different analyses demonstrated greater involvement of specific auditory and motor regions during music perception, as compared to speech vocalizations. This music sensitive network includes bilateral activation of the planum polare and temporale, as well as a group of regions lateralized to the right hemisphere that included the supplementary motor area, premotor cortex and the inferior frontal gyrus. Our results show that the simple act of listening to music generates stronger activation of motor regions, possibly preparing us to move following the beat. Vocal musical listening, with and without lyrics, is also accompanied by a higher modulation of specific secondary auditory cortices such as the planum polare, confirming its crucial role in music processing independently of previous musical training. This study provides more evidence showing that music perception enhances audio-sensorimotor activity, crucial for clinical approaches exploring music based therapies to improve communicative and motor skills.