Poster #18 - Language development and brain reorganization in a child born without the left hemisphere

• In Event: 3-206 - Poster Session 13
  In Poster Session: PS 13 Section - Biological Processes: Neuroscience and Genetics

Integrative Statement

The developing brain has a remarkable ability to reorganize and recover from injuries that would be detrimental to the mature adult brain (Stiles et al, 2005). Here, we examine a case of a 14-year-old girl born without the left hemisphere due to prenatal left internal carotid infarction. Her language development has been followed longitudinally since 14 months of age, allowing us to look at her performance across tasks and across time. Despite having had a delay in getting language off the ground during preschool, at 14 years of age her language performance was within-normal on a variety of standardized language tests (Fig.1), and exceptional in phonology, speech repetition and word reading tasks. She performed within her age average not only on language tasks, but also on spatial, number, and reasoning tasks. We found no evidence of “crowding effect” in the sole (right) hemisphere; in other words, the accommodation of language did not come at the cost of other functions, such as visual or spatial abilities (Teuber, 1975). The fact that her performance on phonology, speech repetition and word reading tasks was superior to the performance of typically developing children is extraordinary given the extent of her lesion, particularly since larger perinatal lesions tend to lead to poorer cognitive outcomes (Booth et al., 2000; Cioni et al., 1999; Levine et al., 2005; Rowe et al., 2009; Sauer et al., 2010). These behavioral outcomes were accompanied by functional and diffusion MRI data (Fig.2). The functional MRI data in our case revealed activation in right fronto-temporal areas when listening to short stories, mirroring left hemisphere activation patterns in controls. The diffusion MRI data showed significantly larger dorsal white matter association tracts (the direct and anterior segments of the Arcuate Fasciculus) connecting areas active during language processing in our case’s remaining right hemisphere, compared to either hemisphere in controls. We hypothesize that these changes in functional and structural brain organization are the result of compensatory brain plasticity. The fact that our case had unusually large right dorsal tracts and exceptional performance in phonology, speech repetition and decoding tasks, speaks in favor of our hypothesis. The large white matter connections might have played a compensatory role by providing fast and reliable transfer of information between cortical areas for language in the right hemisphere. Ours is, to the best of our knowledge, the first study on an individual missing the entire left hemisphere in which longitudinal language and cognitive assessments are combined with functional and structural neuroimaging data in order to situate the case within age-matched, typically developing children.

Authors

• Salomi S Asaridou, University of California, Irvine
  Presenting Author

• Ece Demir-Lira, University of Iowa
  Non-Presenting Author

• Susan Goldin-Meadow, University of Chicago
  Non-Presenting Author

• Susan C. Levine, University of Chicago
  Non-Presenting Author

• Steven L Small, University of California, Irvine
  Non-Presenting Author