Functional MR imaging of vision in the deaf

Rationale and Objectives. Early loss of a sensory modality has been associa ted with cortical reorganization in both animal models and humans. The purp ose of this study was to map visual activation with functional magnetic res onance (MR) imaging and to document possible developmental reorganization i n the temporal lobe caused by early deafness. Materials and Methods. Six prelingual, profoundly deaf subjects were compar ed with a similar group of six hearing subjects. Three visual tasks were pe rformed by both groups: attention to movement in the field-of-view peripher y, shape matching, and mental rotation. Echo-planar coronal MR imaging was performed at 1.5 T. Results. Regions of interest encompassing the middle and posterior aspects of the superior and middle temporal gyri demonstrated a significantly (P < .05) increased activation in deaf subjects compared with hearing subjects, particularly on the fight side (P < .05) and during the tasks involving mot ion. The most specific effect was noted during the mental-rotation task. Conclusion. These results support the hypothesis that portions of the tempo ral lobe usually involved in auditory processing are more active during cer tain visual tasks in deaf compared with hearing subjects. Cortical reorgani zation may be an important factor in the deaf population when considering t he physiology of temporal lobe lesions and predicting surgical outcomes. Fu nctional MR imaging may be helpful during preoperative assessment in indivi duals with deafness.