Many studies in our lab focus on the fact that, as we age, our brains start to use two hemispheres when our younger selves used just one. This phenomenon, called contralateral recruitment, remains controversial because its neural correlates are still poorly understood. To investigate this phenomenon, we used a lateralized word-matching paradigm that emphasized either bilateral or unilateral processing of word relations presented on a screen. We found that older adults benefitted more from bilateral presentations than younger adults; this greater accuracy for bilateral than unilateral trials (bilateral processing advantage [BPA]) also correlated with a number of brain measures. Older adults showed greater contralateral recruitment in the right hemisphere, as well as greater communication between the hemispheres. Critically, older adults who showed a greater BPA also showed greater brain connectivity, indicating that older adults who recruit extra regions engenders changes that allow them to meet the demands of the task.
Davis, S. W., Kragel, J. E., Madden, D.J., & Cabeza, R. (2011). The architecture of Cross-Hemispheric Communication in the Aging Brain: Linking Behavior to Functional and Structural Connectivity. Cerebral Cortex.