The compensatory role of the frontal cortex in mild cognitive impairment: Identifying the target for neuromodulation

Abstract

Introduction: Development of individualized neuromodulation techniques for mild cognitive impairment (MCI) is a feasible practical goal.  Preliminary research exploring the brain-level compensatory reserves on the base of neuroimaging is necessary.  Methods: Twenty-one older adults, representing a continuum from healthy norm to MCI, underwent functional MRI while performing two executive tasks—a modified Stroop task and selective counting.  A functional activation and connectivity analysis were conducted with the inclusion of a BRIEF–MoCA covariate.  This variable represented the difference between the real-life performance measured by Behavior Rating Inventory of Executive Function (BRIEF) and the level of cognitive deficit measured by Montreal Cognitive Assessment (MoCA) Scale, an ability to compensate for impairment.  Results: Both tasks were associated with activation of areas within the frontoparietal control network, along with the supplementary motor area (SMA) and the pre-SMA, the lateral premotor cortex, and the cerebellum.  A widespread increase in the connectivity of the pre-SMA was observed during the tasks.  The BRIEF–MoCA value correlated, first, with connectivity of the left dorsolateral prefrontal cortex (LDLPFC) and, second, with enrollment of the occipital cortex during the counting task.  Conclusion: The developed neuroimaging technique allows identification of the functionally salient target within the LDLPFC in patients with MCI.