Reduced Routing Efficiency in the Right Fronto-Parietal Attentional Network During Distractor Suppression in Mild Cognitive Impairment

Selective attention is a crucial cognitive function facilitates the relevant-sensory-input processing (i.e., targets) and filters out irrelevant information (i.e., distractors). Prior studies illustrated the ability to selectively process behaviorally sensory information declines with age, especially in older adults who exhibit Mild Cognitive Impairment (MCI), a transitional stage from healthy aging to dementia, e.g. Alzheimer’s disease. Less is known regarding how neural mechanisms help eliminating distractors go awry in MCI. We hypothesized the fronto-parietal attentional network, which is involved in distractor suppression mechanisms, undergoes non-typical changes in MCI compared to healthy-aging individuals. To test this hypothesis, we collected scalp-EEG data from MCI and healthy-aging subjects, while they performed various attention-cueing tasks where they had to ignore the presence of color-salient distractors. Using the routing efficiency analysis (RE) on EEG, the measures in social network analysis representing efficiency of communication between two regions within a network, we found the right fronto-parietal network in the healthy control group (HC) was significantly engaged in trials with salient distractors compared to those without. Critically, the saliency effect on RE of the right fronto-parietal EEG coherence at beta-band frequencies decreased in MCI patients compared to HC, without any significant change in behavioral performance at ignoring salient distractors. Hence, results suggest the right fronto-parietal attentional network plays a critical role in suppressing salient distractors in healthy aging and the reduction in RE between the right fronto-parietal areas could be used as a neural marker for attention deficits related to distractor suppression mechanisms in MCI. ​​​​​​​