Conflict-Specific Aging Effects Mainly Manifest in Early Information Processing Stages-An ERP Study with Different Conflict Types

Abstract

Aging is usually accompanied by alterations of cognitive control functions such as conflict processing. Recent research suggests that aging effects on cognitive control seem to vary with degree and source of conflict, and conflict specific aging effects on performance measures as well as neural activation patterns have been shown. However, there is sparse information whether and how aging affects different stages of conflict processing as indicated by event related potentials (ERPs) such as the P2, N2 and P3 components. In the present study, 19 young and 23 elderly adults performed a combined Flanker conflict and stimulus-response-conflict (SRC) task. Analysis of the reaction times (RTs) revealed an increased SRC related conflict effect in elderly. ERP analysis furthermore demonstrated an age-related increase of the P2 amplitude in response to the SRC task. In addition, elderly adults exhibited an increased P3 amplitude modulation induced by incongruent SRC and Flanker conflict trials.

Keywords: Fanker conflict; N2; P2; aging; event-related potentials; stimulus-response conflict.

Figure 1

Experimental task design. The participants were instructed to attend to the color of the central arrow (blue or red) and to react as fast as possible via right or left button press with their index finger. The arrows surrounding the central target could either have the same color as the target (congruent Flanker condition) or the color allocated to the opposite response side (incongruent Flanker condition). Furthermore, all arrows were either oriented to the correct response side as indicated by the color of the central arrow (congruent stimulus-response-conflict (SRC) condition) or pointed to the opposite direction (incongruent SRC condition). There were four experimental conditions: (1) congruent Flanker and SR condition (FcSc); (2) incongruent Flanker and congruent SRC condition (FiSc); (3) congruent Flanker and incongruent SRC condition (FcSi), and (4) incongruent Flanker and SRC condition (FiSi). In the depicted scenario the color “blue” of the central arrow is associated with the left response side and the color “red” with the right response side. The association of color and response side was counterbalanced across participants.

Figure 2

Reaction times (RTs; A) and error rates (B) of young and elderly participants for the conditions fcsc (both Flanker and SRC congruent), fisc (Flanker incongruent, SRC congruent), fcsi (Flanker congruent, SRC incongruent), and fisi (both Flanker and SRC incongruent). Error bars show standard error of mean.

Figure 3

(A) Group-averaged event-related potentials (ERPs) for the conditions FcSc (Flanker and SRC congruent), FiSc (Flanker incongruent, SRC congruent), FcSi (Flanker congruent, SRC incongruent) and FiSi (Flanker and SRC incongruent) for young and elderly adults. Stimulus onset is shown by the vertical line. Ticks on the time axis represent 200 ms. (B) Topography of the P2, N2, and P3 component for young and elderly participants.

Figure 4

(A) Topography of amplitude difference between SRC incongruent—congruent condition for the P2 component (140–220 ms). Blue circles indicate electrodes with a significant SRC amplitude effect. (B) Topography of amplitude difference between Flanker incongruent—congruent condition for the N2 component (240–330 ms). Green circles represent electrodes with a significant Flanker conflict amplitude effect. (C) Topography of amplitude difference between SRC and Flanker incongruent—congruent condition for the P3 component (310–570 ms). Colored circles indicate significant SRC (blue) and Flanker conflict (green) amplitude effects.