Pupil diameter is not an accurate real-time readout of locus coeruleus activity

Megemont, Marine; McBurney-Lin, Jim; Yang, Hongdian

doi:10.7554/elife.70510

Cited by 83 publications

(96 citation statements)

References 108 publications

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“…This assumption is often justified on the basis of the physiological findings that LC neurons spike at the time of salient events ( 8 ) and that LC activity or microstimulation precedes pupil dilation ( 11 , 12 ). Some highly cited papers thus claim that it is possible to infer activity in the LC-NE system from pupil size ( 52 ). This consensus model is nearly identical to one that has been used in functional magnetic resonance imaging (fMRI), in which the strength of neural activity is inferred by regressing a prediction, the convolution of the hemodynamic response function with impulses at trial event times, on the fMRI signal.…”

Section: Discussionmentioning

confidence: 99%

A unified model of the task-evoked pupil response

2022

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The pupil dilates and reconstricts following task events. It is popular to model this task-evoked pupil response as a linear transformation of event-locked impulses, whose amplitudes are used as estimates of arousal. We show that this model is incorrect and propose an alternative model based on the physiological finding that a common neural input drives saccades and pupil size. The estimates of arousal from our model agreed with key predictions: Arousal scaled with task difficulty and behavioral performance but was invariant to small differences in trial duration. Moreover, the model offers a unified explanation for a wide range of phenomena: entrainment of pupil size and saccades to task timing, modulation of pupil response amplitude and noise with task difficulty, reaction time–dependent modulation of pupil response timing and amplitude, a constrictory pupil response time-locked to saccades, and task-dependent distortion of this saccade-locked pupil response.

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Section: Discussionmentioning

confidence: 99%

A unified model of the task-evoked pupil response

2022

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“…Long RTs can also result from involuntary bodily functions (e.g., sneezing or eye movements) or cases 3 Although the present work focuses on overt behavioral measures, recent research has also identified pupil diameter and its changes as potential physiological indicators of sustained attention . Pupil dilations may be indirectly related to LC-NE functioning (Aston-Jones & Cohen, 2005;Rajkowski et al, 1994; but see Megemont et al, 2022) which is linked to overall physiological arousal and attention.…”

Section: Limitations Of Objective Indicators Of Sustained Attentionmentioning

confidence: 99%

A Nomothetic Span Approach to assessing the Construct Validity of Sustained Attention Measures

Welhaf¹,

Kane²

2022

Preprint

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Sustained attention is frequently assessed using either objective behavioral measures, such as reaction-time variability during a task, or subjective self-report measures, such as rates of task-unrelated thought (TUT) during a task. The current studies examined whether the individual-difference overlap in these measures provides a more construct valid assessment of sustained attention ability than does either alone. Whereas prior research typically considered behavioral measures to provide convergent validity for TUT reports, we argue that they mutually validate each other; each measurement approach has its own sources of error, so their shared variance should best reflect the sustained attention construct. We reanalyzed two latent-variable studies where reaction-time variability and TUTs were measured in multiple tasks (Kane et al., 2016, Journal of Experimental Psychology: General, 145, 1017-1048; Unsworth et al., 2021, Journal of Experimental Psychology: General, 150, 1303-1331). These studies also included several nomological-network constructs that allowed for testing the convergent and discriminant validity of a general sustained attention factor. Confirmatory factor analyses assessing bifactor (preregistered) and hierarchical (non-preregistered) models, suggested that sustained attention can be modeled as the shared variance among objective and subjective measures. This sustained attention factor was related to working memory capacity, attention control, processing speed, task-specific motivation and alertness, and self-reported cognitive failures and positive schizotypy. Multiverse analyses of trial- and subject-level outlier decisions suggested that bifactor models of general sustained attention ability are less robust than hierarchical models. The results provide evidence for the general ability to sustain attention and provide suggestions for improving its measurement.

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“…It is likely that the component of the ongoing pupil signal that is behaviorally relevant constitutes a small part of the signal. In fact, studies describing the association between neural activity and ongoing pupil dilation events report significant but small correlations suggesting that a large proportion of the pupil variance remains unexplained ( Joshi et al, 2016 ; Megemont et al, 2022 ; Reimer et al, 2016 ).…”

Section: Discussionmentioning

confidence: 99%

Slow fluctuations in ongoing brain activity decrease in amplitude with ageing yet their impact on task-related evoked responses is dissociable from behavior

Ribeiro

2022

eLife

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In humans, ageing is characterized by decreased brain signal variability and increased behavioral variability. To understand how reduced brain variability segregates with increased behavioral variability, we investigated the association between reaction time variability, evoked brain responses and ongoing brain signal dynamics, in young (N=36) and older adults (N=39). We studied the electroencephalogram (EEG) and pupil size fluctuations to characterize the cortical and arousal responses elicited by a cued go/no-go task. Evoked responses were strongly modulated by slow (<2 Hz) fluctuations of the ongoing signals, which presented reduced power in the older participants. Although variability of the evoked responses was lower in the older participants, once we adjusted for the effect of the ongoing signal fluctuations, evoked responses were equally variable in both groups. Moreover, the modulation of the evoked responses caused by the ongoing signal fluctuations had no impact on reaction time, thereby explaining why although ongoing brain signal variability is decreased in older individuals, behavioral variability is not. Finally, we showed that adjusting for the effect of the ongoing signal was critical to unmask the link between neural responses and behavior as well as the link between task-related evoked EEG and pupil responses.

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Pupil diameter is not an accurate real-time readout of locus coeruleus activity

Cited by 83 publications

References 108 publications

A unified model of the task-evoked pupil response

A unified model of the task-evoked pupil response

A Nomothetic Span Approach to assessing the Construct Validity of Sustained Attention Measures

Slow fluctuations in ongoing brain activity decrease in amplitude with ageing yet their impact on task-related evoked responses is dissociable from behavior

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