Effects of arousal on cognitive control: empirical tests of the conflict-modulated Hebbian-learning hypothesis

Novelty and learning in cognitive control: evidence from the Simon task

While information that is associated with inappropriate responses can interfere with an ongoing task and be detrimental to performance, cognitive control mechanisms and specific contextual conditions can alleviate interference from unwanted information. In the spatial correspondence (Simon) task, interference has been consistently shown to be reduced by spatial non-correspondence in the previous trial (i.e., correspondence sequence effect, CSE); however the mechanisms supporting this sequential effect are not well understood. Here we investigated the role of novelty and trial-to-trial changes in stimulus and response features in a Simon task, observing similar modulation of CSE for novel and non-novel stimulus changes. However, changing the response modality from trial to trial dampened CSE, and this dampening was more pronounced when the probability of switch trials was higher, suggesting a role for long-term learning. The results are consistent with recent accounts, which indicate that spatial interference can be prevented by cognitive control mechanisms triggered by learned bindings.

The Pupil Knows: Pupil Dilation Indexes and Their Inhibitory Ability in Normal Aging

Pupil dilation is considered an index of cognitive effort, as the pupil typically dilates as the cognitive load increases. In this paper, we evaluated whether older adults demonstrate increased pupil size when performing tasks requiring cognitive inhibition. We invited 44 older and 44 younger adults to perform the Stroop task while their pupil dilation was recorded with eye-tracking glasses. The dependent variables were the number of accurate responses on the Stroop task as well as pupil size in the three conditions of the task (i.e., color naming, word reading, and the interference condition). The results demonstrated less accurate responses in the interference condition than in the color-naming or word-reading conditions, in both older and younger adults. Critically, larger pupil dilation was observed in the interference condition than in the color-naming and word-reading conditions, in both older and younger adults. This study demonstrates that pupil dilation responds to cognitive effort in normal aging, at least in the interference condition of the Stroop task.

Pupil dilation as an indicator of future thinking

BACKGROUND

The pupil typically dilates in reaction to cognitive load. In this study, we, for the first time, investigated whether future thinking (i.e., the ability to generate hypothetical scenarios in the future) would result in pupil dilation.

METHODS

We recorded pupil dilation of participants during two conditions: past and future thinking. In past thinking, we invited participants to retrieve past personal events, while in future thinking, we invited them to imagine an event that may occur in the future.

RESULTS

Analysis demonstrated a larger pupil size during future than past thinking. Results also demonstrated longer retrieval time of future events compared with past ones, suggesting that future thinking perhaps requires more cognitive load than for past thinking. Interestingly, retrieval times during past and future thinking were positively correlated with pupil size.

DISCUSSION

The finding that future thinking activates pupil dilation could be due to the fact that while both past and future thinking require retrieving information from memory, future, but not past, thinking additionally requires the ability to recombine this information into novel scenarios.

Emotion and conflict adaptation: the role of phasic arousal and self-relevance

Conflict adaptation reflects the increase in cognitive control after previous conflict between task-relevant and task-irrelevant information. Tonic (sustained) arousal elicited by emotional words embedded in a conflict task has previously been shown to increase conflict adaptation. However, the role of phasic (transient) emotional arousal remains unclear. In Experiment 1 (N = 55), we therefore investigated the effect of phasic arousal using a colour flanker task with negative, positive, and neutral words as stimuli. We hypothesised that phasic arousal elicited in this context will increase conflict adaptation in the subsequent trial. Indeed, when the words were positive or negative as compared to neutral, we observed increased conflict adaptation. In Experiment 2 (N = 54), we examined the role of the self-relevance by presenting words with a self-related pronoun ("my") or sender-related pronoun ("his"/"her"). We expected that emotional words with high self-relevance would lead to stronger effects of emotional arousal on conflict adaptation. Confirming this hypothesis, results showed that emotional words within a self-related context again increased conflict adaptation, whereas this effect was not observed in the sender-related context. Taken together, these results are the first to show that phasic arousal elicited by emotional words increases conflict adaptation, in particular when these words have high self-relevance.

Pupil dilation as an index of effort in cognitive control tasks: A review

Pupillometry research has experienced an enormous revival in the last two decades. Here we briefly review the surge of recent studies on task-evoked pupil dilation in the context of cognitive control tasks with the primary aim being to evaluate the feasibility of using pupil dilation as an index of effort exertion, rather than task demand or difficulty. Our review shows that across the three cognitive control domains of updating, switching, and inhibition, increases in task demands typically leads to increases in pupil dilation. Studies show a diverging pattern with respect to the relationship between pupil dilation and performance and we show how an effort account of pupil dilation can provide an explanation of these findings. We also discuss future directions to further corroborate this account in the context of recent theories on cognitive control and effort and their potential neurobiological substrates.

Differential effects of vestibular processing on orienting exogenous and endogenous covert visual attention

Recent research highlights the overwhelming role of vestibular information for higher order cognition. Central to body perception, vestibular cues provide information about self-location in space, self-motion versus object motion, and modulate the perception of space. Surprisingly, however, little research has dealt with how vestibular information combines with other senses to orient one's attention in space. Here we used passive whole body rotations as exogenous (Experiment 1) or endogenous (Experiment 2) attentional cues and studied their effects on orienting visual attention in a classical Posner paradigm. We show that-when employed as an exogenous stimulus-rotation impacts attention orienting only immediately after vestibular stimulation onset. However, when acting as an endogenous stimulus, vestibular stimulation provides a robust benefit to target detection throughout the rotation profile. Our data also demonstrate that vestibular stimulation boosts attentional processing more generally, independent of rotation direction, associated with a general improvement in performance. These data provide evidence for distinct effects of vestibular processing on endogenous and exogenous attention as well as alertness that differ with respect to the temporal dynamics of the motion profile. These data reveal that attentional spatial processing and spatial body perception as manipulated through vestibular stimulation share important brain mechanisms.

Conflict adaptation within but not across NoGo decision criteria: Event-related-potential evidence of specificity in the contextual modulation of cognitive control

From the standpoint of conflict-monitoring theory (Botvinick et al., 2001), detecting an incident of information-processing conflict should attenuate the disruptive influence of information-processing conflicts encountered subsequently, by which time cognitive-control operations will have been engaged. To examine the generality of this conflict-adaptation process across task dimensions, the present research analyzed event-related potentials in a Go/NoGo task that randomly varied the NoGo decision criterion applied across trials. Sequential analyses revealed reduced-amplitude fronto-central N2 and NoGo P3 responses on the second of two consecutive NoGo trials. Importantly, both of these conflict-adaptation effects were present only when the same NoGo decision criterion was applied across trials n and n-1. These findings support the theory that encountering information-processing conflict focuses attention on specific stimulus-response contingencies (Verguts & Notebaert, 2009) rather than engages general cognitive-control mechanisms (Freitas & Clark, 2015). Further implications for the generality of cognitive control are discussed.

Beta receptor-mediated modulation of the oddball P3 but not error-related ERP components in humans

RATIONALE

The P3 is a ubiquitous component of stimulus-driven neural activity that can be observed in scalp electrophysiological recordings. Multiple lines of evidence suggest an important role for the noradrenergic system in the generation of the P3. However, pharmacological studies of the P3 using noradrenergic manipulations have so far been limited to agents that affect α2-receptor signaling.

OBJECTIVES

The present study investigated whether β-adrenergic receptors are involved in the generation of the P3 and the error positivity (Pe), a component of the event-related potential that is elicited by errors and that bears many similarities to the P3.

METHODS

We used a double-blind, placebo-controlled, crossover design in which we examined in human participants (N = 16) the effect of a single dose of propranolol (80 mg) on the amplitudes of the P3 observed in visual and auditory oddball tasks and the Pe observed in a flanker task.

RESULTS

We found that P3s to auditory stimuli were increased in amplitude following treatment with propranolol. Propranolol also modulated the P3 to visual stimuli, but in a direction dependent on participants' level of trait anxiety: In participants with lower trait anxiety, propranolol resulted in a (non-significant) decrease in P3 amplitudes; in participants with higher trait anxiety, propranolol significantly enhanced P3 amplitude. Propranolol did not modulate the amplitude of the Pe or behavioral measures of conflict/error-related performance adjustments.

CONCLUSIONS

These results provide the first evidence for involvement of β-adrenergic receptors in P3 generation. We speculate that propranolol affected the P3 through actions at β2-receptors in the locus coeruleus.