Age-related effects on event-related brain potentials in a congruence/incongruence judgment color-word Stroop task

Abstract

We examined the event-related brain potentials elicited by color-word stimuli in a Stroop task in which healthy participants (young and old) had to judge whether the meaning and the color of the stimulus were congruent or incongruent. The Stroop effect occurred in both age groups, with longer reaction times in the older group than in the young group for both types of stimuli, but no difference in the number of errors made by either group. Although the N2 and P3b latencies were longer in the older than in the younger group, there were no differences between groups in the latencies of earlier event-related potential components, and therefore the age-related processing slowing is not generalized. The frontal P150 amplitude was larger, and the parietal P3b amplitude was smaller, in the older than in the younger group. Furthermore, the P3b amplitude was maximal at frontal locations in older participants and at parietal locations in young participants. The age-related increase in perceptual resources and the posterior-to-anterior shift in older adults support adaptive reorganization of the neural networks involved in the processing of this Stroop-type task.

Dual-task and electrophysiological markers of executive cognitive processing in older adult gait and fall-risk

“…A congruent/incongruent judgment Stroop task (word-color stimuli: Stroop, 1935 ) was administered to assess executive sustained attention, conflict monitoring and response adaptation/switching (Zurrón et al, 2009 , 2014 ). This task visually presented the words “RED”, “GREEN”, “YELLOW” and “BLUE” in either their congruent font color (“RED” in red type) or an incongruent color (“RED” in blue type).…”

“…Event-related potential (ERP) components were identified and defined based on visual-inspection and previous literature (Mager et al, 2007 ; Killikelly and Szűcs, 2013 ; Gajewski and Falkenstein, 2014 ; Zurrón et al, 2014 ). ERP segmentations time-locked to stimulus onset were set and averaged in BESA; epoch length −200 to 1,000 ms, with a −200 to 0 ms pre-stimulus baseline correction interval.…”

“…We only identified one later positivity after the N2, presenting at midline Pz and Oz between 200–385 ms post stimulus for both the younger and ONF groups (but not the OF). This component was considered to be an early P3a, based on similar windows and sites reported recently on an equivalent Stroop judgment task (Mager et al, 2007 ; Zurrón et al, 2009 , 2014 ; Killikelly and Szűcs, 2013 ). While previous studies have defined the P3a within the window of 300–450 ms post stimulus (Eppinger et al, 2007 ), more recent investigations of Stroop-related ERPs in young and older adults investigate earlier windows: Killikelly and Szűcs ( 2013 ) analyzed an early P3 peak as early as 180–230 ms in young adults, and 250–335 ms in comparable middle aged/older adults.…”

“…The main hypotheses were: (1) there would be subtle gait impairments (slower speed, increased variability) in older adult fallers in comparison to non-fallers and young adults; (2) higher-level EF DTs would affect gait (speed, stride time, variability) comparatively more than basic attention and motor response tasks, with greater effects seen in older adults; (3) age-related and fall-related poorer EF performances would relate to subtle gait impairments; and (4) EF-related later ERP components (N2, P3) would reflect behavioral and gait impairments in fallers compared to non-fallers, and compared to younger adults. More specifically, we want to investigate if P3 amplitude is reduced in older adults (as previously reported by Mager et al, 2007 ; Zurrón et al, 2014 ), and more so in older fallers, who may have limited available neural resources for allocation to task demands.…”

“…Experiment 2 aims to establish if event-related potential (ERP) markers of executive impairment can be found in older fallers in contrast to older non-fallers, by comparing working memory and sustained attention/conflict processing performances with gait performance and history of falls status. An n-Back and Stroop task were used to target these two different types of executive functioning (EF) which have been shown to correlate with gait and falls, and greater DT costs (as outlined above: Beurskens and Bock, 2012 ), and which have previously defined age-related ERP components for comparison (Gajewski and Falkenstein, 2014 ; Zurrón et al, 2014 ). While the continued advancement of mobile-EEG recording will surely enhance understanding of the supraspinal activity underlying gait, the current study aimed to utilize accessible and applicable methods which could potentially translate to a clinical setting.…”