Learning morphological inflections in an artificial language

Learning of new morphological inflections may serve as a model for studying the learning mechanisms underlying the acquisition of language skills. We used an artificial oral language and fMRI to study the effect of statistical factors on the mechanisms involved in the acquisition of plural inflections. We found that the inflection frequency and its phonological diversity critically affect the brain mechanisms involved in its acquisition. This artificial language paradigm was also used in our recent study to look at developmental differences in the effect of sleep on the acquisition of morphological inflections. Our results show better consolidation and greater reliance on procedural learning mechanisms in children, while adults were more affected by sleep and relied to a greater extent on declarative learning. 

Effects of orthography and experience on reading

Reading- Hebrew:
Findings from the last decade, demonstrating the enormous malleability of the nervous system are consistent with reading theories suggesting that the neurocognitive mechanisms involved in reading depend on the properties of the specific language and the readers’ experience with its orthography. The Hebrew Language and orthography provide a unique opportunity to study the effect of orthographic transparency (diacritic marks and vowel letters) and morphological complexity (roots and templates) on the brain of skilled and non- skilled (young or dyslexic) readers. Our results show a critical effect for the reader’s experience, that overrides the effect of the specific orthography. In addition we find effects of individual characteristics such as Dyslexia or gender on the neurocognitive reading process. 
Reading - English:
Children acquiring reading in English have to master the irregularity of the writing system.  In collaboration with the lab of James Booth, at Northwestern University, we studied developmental changes in brain connectivity while children learn to cope with conflicting orthographic and phonological information. Using an analysis method for looking at directional interactions among brain regions (Dynamic Causal Modeling) we identified task specific convergence zones integrating top-down and bottom-up influences. We have also shown a developmental increase in top-down control processes, providing an account for children’s greater susceptibility to distractions from irrelevant information. The same analysis technique enabled us to look at inter-hemispheric connectivity, showing reciprocal influences between hemispheres which were greater for girls compared to boys. These finding can explain some of the behavioral evidence for sex differences in language ability.
Reading – Artificial Orthography:
We use an artificial orthography to study the effect of the readers experience on the brain mechanisms involved in learning to read. The comparison or explicit and implicit instruction methods, in our earlier studies, showed that different instruction methods resulted in differential reliance on procedural learning, and that only explicit instruction on the smallest repeating units in the words resulted in improved consolidation after the end of training. Our recent study has showed that a variable set of trained items results in better learning, demonstrating a critical role for the statistical properties of the input for determining the content and process involved in learning. 

Brain connectivity in post-stroke patients with Aphasia:

Patients with acquired brain lesions suffering from Aphasia often have disrupted brain connectivity within and between hemispheres. In a study done in collaboration with Dr. Jed Meltzer from the Rotman-Baycrest Research Institute we found that excitatory right to left connectivity at the level of the auditory cortex is associated with good recovery. In a treatment study with Prof. Elizabeth Rochon from the University of Toronto we found increased Resting State connectivity between right language areas and motor speech control areas following melody-based therapy.