Neuroplasticity of explicit memory during training – a fMRI study in normal aging and MCI

Introduction: In patients with mild cognitive impairment (MCI), mnestic deficits occur long before the onset of dementia. During follow-up, memory decline proceeds in these patients whereas cognitively unimpaired older persons show a stable memory performance. In order to investigate the neural basis underlying cognitive training effects in probands at risk to develop Alzheimer's disease (AD) and in healthy controls we developed a fMRI paradigm of explicit memory function.

Methods: 11 patients with MCI and 11 controls were enrolled in the study. Before and after an one-week-training period all participants underwent fMRI scan during verbal memory encoding. Image analysis was done using statistical parametric mapping.

Results: In healthy controls, before training a temporal, parietal, cingulate, and left frontal cortex activation occurred which decreased after the one-week-cognitive training. In contrast, MCI patients showed at baseline a rather week temporal, cingulate and left frontal cortex activation which increased after training.

Conclusion: In conclusion, the results of this study demonstrate an economisation of cerebral activity in healthy persons after training whereas in the MCI patients after training a compensation for cerebral activation deficits occurs.