Article

Mild cognitive impairment (MCI) is often a precursor to Alzheimer
disease. Little research has examined the efficacy of cognitive rehabilitation in
patients with MCI, and the relevant neural mechanisms have not been explored. The
authors previously showed the behavioral efficacy of cognitive rehabilitation
using mnemonic strategies for face-name associations in patients with MCI. Here,
the authors used functional magnetic resonance imaging (fMRI) to test whether
there were training-specific changes in activation and connectivity within
memory-related areas. METHODS: A total of 6 patients with amnestic, multidomain
MCI underwent pretraining and posttraining fMRI scans, during which they encoded
90 novel face-name pairs and completed a 4-choice recognition memory test
immediately after scanning. Patients were taught mnemonic strategies for half the
face-name pairs during 3 intervening training sessions. RESULTS:
Training-specific effects comprised significantly increased activation within a
widespread cerebral cortical network involving medial frontal, parietal, and
occipital regions; the left frontal operculum and angular gyrus; and regions in
the left lateral temporal cortex. Increased activation common to trained and
untrained stimuli was found in a separate network involving inferior frontal,
lateral parietal, and occipital cortical regions. Effective connectivity analysis
using multivariate, correlation-purged Granger causality analysis revealed
generally increased connectivity after training, particularly involving the
middle temporal gyrus and foci in the occipital cortex and the precuneus.
CONCLUSION: The authors' findings suggest that the effectiveness of
explicit-memory training in patients with MCI is associated with
training-specific increases in activation and connectivity in a distributed
neural system that includes areas involved in explicit memory.

Langue : ANGLAIS