A Behavioral Manipulation Engages Right Frontal Cortex During Aphasia Therapy

Background. An aphasia treatment was designed to shift laterality from the left to right lateral frontal lobe during word production by initiating word-finding trials with complex left-hand movements. Previous findings indicated successful relateralization. Objective. The current study was designed to ascertain whether the shift was attributable to the left-hand movement. Methods. Using stratified random sampling, 14 subjects were equally divided between Intention (IT) and Control (CT) treatments. CT was identical to IT, except with no left-hand movements. Both treatments trained picture naming (phases 1 and 2) and category-member generation (phase 3), each phase lasting 10 sessions. Functional magnetic resonance imaging of category member generation occurred at pretreatment, posttreatment, and 3-month follow-up. Results. IT shifted lateral frontal activity rightward compared with pretreatment both at posttreatment (t = -2.602, df = 6, P < .05) and 3-month follow-up (t = -2.332, df = 5, P < .05), but CT did not. IT and CT yielded similar changes for all picture-naming and category probes. However, IT patients showed gains for untrained category (t = 3.33, df = 6, P < .01) and picture-naming probes (t = 3.77, df = 5, P < .01), but CT patients did not. Conclusions. The rightward shift in lateral frontal activity for IT was because of the left-hand movements. IT evoked greater generalization than CT.