Devleopmnet of Distriubted Nueral Sysetms for Readnig in Heatlhy and Brian-Injrued Chlidren (If you can read this, you have a well-developed whole word reading system. It should read Development of Distributed Neural Systems for Reading in Healthy and Brain-Injured Children)

Printed words can be read by decoding, which involves mapping the visual form to its auditory counterpart before meaning is accessed, or directly, by linking meaning to the word form as a whole. Clinical cases and neuroimaging studies have suggested separate, yet interacting, neural pathways may underlie these strategies to reading. Children developing expertise in reading may show a concomitant decrease in reliance on posterior phonological systems supporting decoding as well as an increase in specialization of visual systems. However, the functional organization of these neural systems is not well understood, particularly in light of the fact that reading is a cultural invention too recent to have evolved dedicated brain mechanisms. In the present thesis, we manipulated word frequency and spelling-to-sound consistencies to favor one or the other reading strategy in young readers aged 7-10. Functional magnetic resonance imaging (fMRI) recordings demonstrate that more proficient young readers use inferior frontal regions rather than dorsal inferior parietal and temporal phonological regions during the direct reading strategy, whereas the opposite brain activity pattern supports the less efficient decoding strategy. Moreover, both left and right fusiform gyri participate in functional networks supporting both reading strategies by interacting with left inferior parietal regions during direct reading and inferior frontal and bilateral ventral occipital areas during decoding; however, left fusiform gyrus appears to show a relative specialization for direct reading. Further investigation of the fusiform gyri reveals more dissociable patterns of activity for words versus non-lexical stimuli in young readers compared to adults, suggesting an increase in specialization of visual systems. We argue that this reflects increased local processing and decreased distributed network processing associated with earlier stages of development. Finally, the capacity of functional neural regions to increase their ability to connect to other regions within the reading network may be important for recovery in young readers with pre- or perinatally acquired focal lesions.

Department dc:contributor.department

Psychology

Year dc:date.issued

2012

Author dc:creator

• Raja, Anjali

Advisor dc:contributor.advisor

• McIntosh, Anthony Randal

• reading
• fMRI
• development
• stroke
• neural networks
• partial least squares
• cognitive neuroscience

Language dc:language.iso

en_ca

Handle dc:identifier.uri

http://hdl.handle.net/1807/68958

OAI identifier oai:identifier

oai:utoronto.scholaris.ca:1807/68958