Anne van der Kant
Utrecht University
Neural mechanisms underlying sensitive period effects on vocal leaning in songbirds and humans
Based on data showing that children readily learn a new language that is presented to them, while
adults struggle, it has been hypothesized that language is learned within a sensitive period early in
life. Sensitive periods for vocal learning are not uniquely human, as songbirds like zebra finches
also need to be exposed to the vocalizations of their parents within this sensitive period in order to
develop their own. Therefore, songbirds present an excellent model for studying human speech
acquisition.
In order to gain insight in the neural mechanisms underlying sensitive period effects on vocal
leaning in both species we used auditory fMRI in songbirds and humans. Our studies in adult and
juvenile zebra finches showed that a neural selectivity for the tutor’s song (which is learned by the
juvenile) emerges in the left auditory midbrain during song learning, but that the right auditory
midbrain shows this selectivity for the tutor’s song in adulthood. This shift might reflect the change in
function of the tutor’s song.
Human language might also be processed differently within or outside the sensitive period.
To investigate this, we have collected fMRI data from human adults during auditory exposure to an
artificial grammar containing non-adjacent dependencies. After the initial exposure phase learning
and generalization of the artificial grammar are tested. Additionally, resting state data are acquired
before and after the learning phase in order to determine the influence of artificial grammar learning
on functional connectivity. Preliminary data from the adult group show changes in neural
recruitment of IFG during leaning.
This experiment will be repeated in pre-pubertal children in order to assess sensitive-period
effects on artificial grammar learning.