Pediatric and Developing Brains. Neonates to Adolescents

(Han, Ansari, Joanisse, Morton, Cusack, Menon)

Functional neuroimaging in pediatrics (incl. neonates) is highly challenging. Motion artifacts result in significant rejection of data, and limited attention spans place severe restrictions on paradigm length. Ongoing multi-modality research programs are studying neurocognitive development in infants and children, both from the standpoint of normal development, and within the context of developmental disorders (e.g. autism spectrum disorders). New MRI developments are essential for the extension of fMRI, DTI and other advanced MRI/MRS protocols into neonatal populations, for whom diagnostic and prognostic tools for future quality-of-life are extremely limited.

Neonatal Neuroimaging. Perinatal brain injury is a major health problem of rising incidence with potential life-long consequences. It can lead to cognitive and behavioural abnormalities including cerebral palsy, epilepsy and learning difficulties. The behavioural, neuroanatomical and electrophysiological abnormalities detectable by currently available methodologies are poor predictors of long-term impairments. While there has been much research on the functional evaluation of the brain in adults using the tools of cognitive neuroscience (particularly EEG/ERPs and fMRI), these methods have not yet been adapted to provide valuable clinical tools to assess neonatal brain function.  Research in this theme is aimed at advancing MRI technology to develop tools that will allow prediction of long-term neuro-cognitive outcomes that can be administered non-invasively in the first week(s) of life. Prof. Cusack is optimizing MR parameters to match the long relaxation times of the neonatal brain at 3T, deal with the large movements and develop real-time slice reorientation using the M-R Eye. The auditory system is well developed at birth and can provide a measure of cortical reactivity and the integrity of the ascending neural pathway through the brainstem and midbrain using fMRI. Working with Grahn, beat-based rhythms will be used to stimulate the motor system (disrupted in cerebral palsy) and by varying the timescale of repetition, memory can be probed. The presentation of complex sounds will test sound recognition, and the repetition of patterns will probe statistical learning (both critical in normal language trajectories). NSERC/CIHR has just awarded a CHRP grant for the fMRI study of neonates to Cusack and Han.

Neuroimaging in Children. Currently we focus our research on school age children (≥6yrs old), due to the difficulty that younger children can have with remaining still during 45-60 minute MRI session even with tools like our “0 T” simulator and system to provide motion feedback to children during practice. New infrastructure will allow neuroimaging of younger children through faster volume acquisition and real time motion correction. Studies of pre-literate (<6yrs) children at risk for dyslexia or pre-numerate children at risk for dyscalculia provide critical insights into early identification, and causation at the neural level. Early intervention is key, and members of the team are using fMRI and MRI to investigate the effects of early intervention in the domains of reading, number and cognitive control on the brain. Prof. Ansari’s research examines the development of mathematical abilities in children, with specific regard to how they develop a sense of number, and subsequently learn to enumerate and calculate. This will also involve studying children with dyscalculia, a learning disorder that is marked by impairment in numerical calculation abilities. Prof. Morton studies the development of mental flexibility and cognitive control and seeks to identify the neural substrates of these abilities (such as the dorsolateral prefrontal cortex) and trace their functional development over childhood, using simultaneous event related potentials (ERPs) and fMRI. Prof. Joanisse investigates typical and atypical oral language development in these younger children. He focuses on identifying the earliest risk factors for language and reading disorders, including developmental dyslexia. This will include ERP studies of both spoken and written language processing in children with and without dyslexia or oral language impairment, following up on a recently completed study that has used fMRI to examine spoken language processing deficits in children with dyslexia. The ability to acquire both ERP (with the Geodesics system) and fMRI within a single session at either field strength would allow us to maximize the complementary strengths of the two, allowing us to know both the “where” and “when” of neural processes in developing brains.