Biology subjects

Laeng, B.

Publications and source records attributed to Laeng, B..

4 recordsLinked to original sources

bioRxiv2026

Pupil size reflects moment-to-moment fluctuations in mental imagery, but not (or hardly) individual differences in imagery

Previous research has shown that the eyes pupils are larger when imaging dark as compared to bright objects or scenes. Based on this, it has been claimed that pupil size is a sensitive marker of mental-imagery vividness. We investigated this claim in three experiments, conducted in two countries (Norway and The Netherlands; Ntotal = 115), in which participants read, listened, or freely imagined stories that evoked a sense of darkness or brightness. In addition, participants rated their imagery vividness after each story, as a measure of moment-to-moment fluctuations in imagery; and their imagery vividness in general, as a measure of individual differences in imagery. Overall, we found that darkness-evoking stories induced larger pupils than brightness-evoking stories, although this effect was highly variable and only statistically reliable for longer (> 1 min) audio stories. Importantly, we consistently found that this pupil-size difference (dark - bright) was largest for vividly imagined stories. Finally, we did not find any relationship between this pupil-size difference and individual differences in general in imagery. We conclude that the strength of pupil-size changes in response to imagined darkness or brightness reflects moment-to-moment fluctuations in imagery vividness within an individual rather than individual differences in imagery vividness as a personal trait.

neuroscience↗

bioRxiv2024

ILLUSORY LIGHT DRIVES PUPIL RESPONSES IN PRIMATES

In humans, the eye pupils respond to both physical light sensed by the retina and mental representations of light produced by the brain. Notably, our pupils constrict when a visual stimulus is illusorily perceived brighter, even if retinal illumination is constant. Yet, it remains unclear whether such perceptual penetrability of pupil responses is an epiphenomenon unique to humans or whether it represents an adaptive mechanism shared with other animals to anticipate variations in retinal illumination between successive eye fixations. To address this issue, we measured the pupil responses of both humans and macaque monkeys exposed to three chromatic versions (cyan, magenta, and yellow) of the Asahi brightness illusion. We found that the stimuli illusorily perceived brighter or darker trigger differential pupil responses that are very similar in macaques and human participants. Additionally, we show that this phenomenon exhibits an analogous cyan bias in both primate species. Beyond evincing the macaque monkey as a relevant model to study the perceptual penetrability of pupil responses, our results suggest that this phenomenon is tuned to ecological conditions since the exposure to a "bright cyan-bluish sky" may be associated with increased risks of dazzle and retinal damages.

animal behavior and cognition↗

bioRxiv2020

The ascending arousal system promotes optimal performance through meso-scale network integration in a visuospatial attentional task

Previous research has shown that the autonomic nervous system provides essential constraints over ongoing cognitive function. However, there is currently a relative lack of direct empirical evidence for how this interaction manifests in the brain at the macro-scale level. Here, we examine the role of ascending arousal and attentional load on large-scale network dynamics by combining pupillometry, functional MRI and graph theoretical analysis to analyze data from a visual motion-tracking task with a parametric load manipulation. We found that attentional load effects were observable in measures of pupil diameter and in a set of brain regions that parametrically modulated their BOLD activity and meso-scale network-level integration. In addition, the regional patterns of network reconfiguration were correlated with the spatial distribution of the 2a adrenergic receptor. Our results further solidify the relationship between ascending noradrenergic activity, large-scale network integration, and cognitive task performance. Author SummaryIn our daily lives, it is usual to encounter highly demanding cognitive tasks. They have been traditionally regarded as challenges that are solved mainly through cerebral activity, specifically via information-processing steps carried by neurons in the cerebral cortex. Activity in cortical networks thus constitutes a key factor for improving our understanding cognitive processes. However, recent evidence has shown that evolutionary older players in the central nervous system, such as brainstems ascending modulatory systems, might play an equally important role in diverse cognitive mechanisms. Our article examines the role of the ascending arousal system on large-scale network dynamics by combining pupillometry, functional MRI and graph theoretical analysis.

neuroscience↗

bioRxiv2018

Distinct neural mechanisms meet challenges in dynamic visual attention due to either load or spatial interference

When solving dynamic visuo-spatial tasks, the brain copes with perceptual and cognitive processing challenges. In the multiple-object tracking (MOT) task, the number of objects to be tracked (i.e. load) imposes attentional demands, but so does spatial interference from irrelevant objects (i.e. crowding). Presently, it is not clear whether load and crowding activate separate cognitive and physiological mechanisms. Such knowledge would be important to understand the neurophysiology of visual attention. Furthermore, it would help resolve conflicting views between theories of visual cognition, particularly concerning sources of capacity limitations. To address this problem, we varied the degree of processing challenge in the MOT task in two ways: First, the number of objects to track, and second, the spatial proximity between targets and distractors. We first measured task-induced pupil dilations and saccades during MOT. In a separate cohort we measured fMRI brain activity during MOT. The behavioral results in both cohorts revealed that increased load and crowding led to reduced accuracy in an additive manner. Load was associated with pupil dilations, whereas crowding was not. Activity in dorsal attentional areas and frequency of saccades were proportionally larger both with higher levels of load and crowding. Higher crowding recruited additionally ventral attentional areas that may reflect orienting mechanisms. The activity in the brainstem nuclei ventral tegmental area/substantia nigra and locus coeruleus showed clearly dissociated patterns. Our results constitute convergent evidence from independent samples that processing challenges due to load and object spacing may rely on different mechanisms.

neuroscience↗