Linking tonic and phasic pupil responses to P300 amplitude in an emotional face‐word Stroop task

Abstract

The locus coeruleus‐norepinephrine (LC‐NE) system, which regulates arousal levels, is important for cognitive control, including emotional conflict resolution. Additionally, the LC‐NE system is implicated in P300 generation. If the P300 is mediated by the LC‐NE system, and considering the established correlations between LC activity and pupil dilation, P300 amplitude should correlate with task‐evoked (phasic) pupil dilation on a trial‐by‐trial basis. However, prior studies, predominantly utilizing oddball‐type paradigms, have not demonstrated correlations between concurrently recorded task‐evoked pupil dilation and P300 responses. Using a recently developed emotional face‐word Stroop task that links pupil dilation to the LC‐NE system, here, we examined both intra‐ and inter‐individual correlations between task‐evoked pupil dilation and P300 amplitude. We found that lower accuracy, slower reaction times, and larger task‐evoked pupil dilation were obtained in the incongruent compared to the congruent condition. Furthermore, we observed intra‐individual correlations between task‐evoked pupil dilation and P300 amplitude, with larger pupil dilation correlating with a greater P300 amplitude. In contrast, pupil dilation did not exhibit consistent correlations with N450 and N170 amplitudes. Baseline (tonic) pupil size also showed correlations with P300 and N170 amplitudes, with smaller pupil size corresponding to larger amplitude. Moreover, inter‐individual differences in task‐evoked pupil dilation between the congruent and incongruent conditions correlated with differences in reaction time and P300 amplitude, though these effects only approached significance. To summarize, our study provides evidence for a connection between task‐evoked pupil dilation and P300 amplitude at the single‐trial level, suggesting the involvement of the LC‐NE system in P300 generation.

Correlated P300b and phasic pupil‐dilation responses to motivationally significant stimuli

“…Previous studies examining the relation between pupil dilations and P300 in the context of the oddball task did not attempt to separate action-and stimulus-related components. It is interesting to note that the one study that reported correlated pupil-dilation and P300 responses (Chang et al, 2023) used a task that equated the action components across stimulus categories; for their interindividual correlation analyses, they estimated pupil responses by subtracting traces for incongruent and congruent trials, which effectively factored out the actionrelated component from pupil-dilation responses.…”

“…Since the 2011 review paper, several experiments have addressed this issue. To our knowledge, there is only one recent study reporting correlated P300 and pupil dilation responses in the context of a Stroop paradigm (Chang et al, 2023). However, all previous studies using the oddball paradigm failed to detect a significant association between the phasic pupil-dilation response elicited by an oddball stimulus and the amplitude of the P300 (Hong et al, 2014;Kamp & Donchin, 2015;LoTemplio et al, 2021;Murphy et al, 2011).…”

Investigating causal effects of pupil size on visual discrimination and visually evoked potentials in a Snellen eye chart task

“…Stimuli were viewed monocularly with the left eye while the right eye was covered with a patch, mimicking the standard practice of Snellen eye chart test. Following our previous study 25 , EEG 5 data were recorded and sampled at 1000 Hz using a 32-channel Brain Products system (actiCHamp, Brain Products), and the electrodes were positioned according to the standard international 10-20 system. A common vertex reference was placed between Cz and CPz.…”

“…Following our previous study for EEG offline-preprocessing 25 , the raw EEG data were analyzed in MATLAB using the Automagic pipeline 27 . We followed previously implemented procedures 28,29 .…”