Progress beyond the state of the art
We consider our power calculation framework and our preprocessing pipeline as significant advances beyond the state of the art in developmental cognitive neuroscience. Specifically, we are working on a probabilistic statistical framework for a priori power calculation for longitudinal fMRI studies based on Bayesian inference of population prevalence. Moreover, we are working on an integrated approach for preprocessing longitudinal developmental magnetic resonance imaging data in accordance with international open source standards.
Expected results
Our expectations are guided by a behavioral model of learning to read distinguishing between a preliterate, an alphabetic and an orthographic stage of learning to read (Frith, 1986). In this model, the transition from the preliterate to the alphabetic stage requires learning of the links between speech sounds (phonemes) and letters and the orthographic stage is then entered when letter strings are stored in memory as whole words to instantly access their meanings.
Following this behavioral model we expect that the alphabetic stage of literacy is reached when phoneme-sensitive nerve cell populations within the left posterior superior temporal sulcus start responding to letters (first hypothesis). Moreover, we expect that the orthographic stage of literacy is reached as soon as the left middle fusiform cortex responds to auditorily presented words and visually presented words with increasing similarity (second hypothesis). Finally, we expect that learning to read alters phonological representations such that a set of uncommitted anterior parts of the left posterior superior temporal gyrus, broadly responding to both phonemic and non-phonemic auditory stimuli at a preliterate age, selectively attune to phonemes in the course of literacy instruction (third hypothesis).
