Electrophysiological Correlates of Amnestic Mild Cognitive Impairment in a Simon Task

Abstract

Amnestic mild cognitive impairment (aMCI) represents a prodromal stage of Alzheimer`s disease (AD), especially when additional cognitive domains are affected (Petersen et al., 2009). Thus, single-domain amnestic MCI (sdaMCI) and multiple-domain-amnestic MCI (mdaMCI) biomarkers are important for enabling early interventions to help slow down progression of the disease. Recording event-related potentials (ERPs) is a non-invasive and inexpensive measure of brain activity associated with cognitive processes, and it is of interest from a clinical point of view. The ERP technique may also be useful for obtaining early sdaMCI and mdaMCI biomarkers because ERPs are sensitive to impairment in processes that are not manifested at behavioral or clinical levels. In the present study, EEG activity was recorded in 25 healthy participants and 30 amnestic MCI patients (17 sdaMCI and 13 mdaMCI) while they performed a Simon task. The ERPs associated with visuospatial (N2 posterior-contralateral – N2pc -) and motor (lateralized readiness potential – LRP –) processes were examined. The N2pc amplitude was smaller in participants with mdaMCI than in healthy participants, which indicated a decline in the correlates of allocation of attentional resources to the target stimulus. In addition, N2pc amplitude proved to be a moderately good biomarker of mdaMCI subtype (0.77 sensitivity, 0.76 specificity). However, the LRP amplitude was smaller in the two MCI groups (sdaMCI and mdaMCI) than in healthy participants, revealing a reduction in the motor resources available to execute the response in sdaMCI and mdaMCI patients. Furthermore, the LRP amplitude proved to be a valid biomarker (0.80 sensitivity, 0.92 specificity) of both amnestic MCI subtypes.

Neural Dynamics of Multiple Object Processing in Mild Cognitive Impairment and Alzheimer’s Disease: Future Early Diagnostic Biomarkers?

“…However, the patients enrolled in the present study were in the early (mild AD) and in the prodromal phase (MCI) of the disease; therefore, a decline in the N2pc component in the later stages of the disease (i.e., moderate AD) cannot be ruled out. Contrary to the present finding, Cespon and colleagues [41,42] reported a reduction of N2pc amplitude in multi-domain amnestic MCI patients as compared to healthy elderly, suggesting the utility of N2pc to early identify a specific MCI subtype. The discrepant finding may be due to the experimental differences between the studies.…”

Inhibition deficit in the spatial tendency of the response in multiple-domain amnestic mild cognitive impairment. An event-related potential study

“…In a recent study, we observed altered spatial attention toward a lateralized target stimulus, as revealed by the smaller amplitude of the negativity posterior contralateral (N2pc) in mdaMCI participants than in healthy controls (Cespón et al, 2013a ). N2pc is an ERP correlate of the direction of the spatial attention to lateralized stimuli (Luck and Hillyard, 1994 ; Woodman and Luck, 1999 ; Hickey et al, 2009 ).…”

“…In those cases in which the required response is on the opposite side to the stimulus (incompatible condition), a type of interference known as the Simon effect is observed; this leads to increased reaction time (RT) and percentage of errors (PE) (for reviews, see Proctor et al, 2005 ; Leuthold, 2011 ). Several studies have shown that interference in Simon tasks increases with age of participants (van der Lubbe and Verleger, 2002 ; Proctor et al, 2005 ; Juncos-Rabadán et al, 2008 ) and it is even greater in participants with MCI (Cespón et al, 2013a ; Pereiro et al, 2014 ). However, changes in neural mechanisms underlying cognitive control processes in Simon tasks have not been studied in MCI persons.…”

The Effects of Amnestic Mild Cognitive Impairment on Go/NoGo Semantic Categorization Task Performance and Event-Related Potentials

“…These cognitive processes include stimulus evaluation, response execution and inhibition, conflict monitoring, planning, organizing, and decision making [10][11][12][13], all of which play a role in day-to-day activities. To characterize cognitive control and its deficits in individuals with MCI, a variety of clinical (e.g., Behavior Rating Inventory of Executive Function, the Stroop color-word task, Wisconsin Card Sorting Test, Trails B, Letter fluency) and experimental measures (e.g., the Brown-Peterson task, the Hayling task, Erickson flanker task, the Simon task, Go/NoGo task, the stop signal task) have been used [14][15][16][17][18][19][20][21][22][23][24]. Here we report on electrophysiological correlates of cognitive control involved in execution and inhibition of a response in a cohort with aMCI and a group of cognitively normal controls.…”