Decreased Parietal Cortex Activity during Mental Rotation in Children with Congenital Hypothyroidism

Background: The ability to detect the spatial characteristics of objects and to rotate them mentally is frequently impaired in early treated congenital hypothyroidism (CH) children. Aims: To explore the neural substrate of the visuospatial difficulty in children with CH, we studied 15 children with CH (8-10 years) and 13 age-matched control children with functional magnetic resonance imaging (fMRI) using a mental rotation task (VST). Results: Performance at VST was significantly different between the two groups. Moreover, fMRI data showed greater activation in the superior parietal cortex in control children while children with CH had greater activation in the bilateral SMA and the opercular region of the precentral gyrus, the adjacent insula and the left somatosensory parietal cortex. Furthermore, children with CH deactivated the inferior parietal cortex (Brodmann area 40) more than controls. Conclusion: We suggest that the poorer performance of children with CH on VST task is related to the decreased activation in brain areas important for the mental representation of the objects' spatial characteristics, with increased recruitment of regions involved in the representation of somatosensory whole-body information. More studies will be necessary to understand if this different effectiveness in VST reflects immaturity of the neural system or its actual impairment. Copyright (C) 2008 S. Karger AG, Basel