Effects of pupillary light and darkness reflex on the generation of pro‐ And anti‐saccades

Abstract

Saccades are often directed toward a stimulus that provides useful information for observers to navigate the visual world. The quality of visual signals of a stimulus is influenced by global luminance, and the pupil constricts or dilates after a luminance increase or decrease, respectively, to optimize visual signals for further information processing. Although luminance level changes regularly in the real environment, saccades are mostly studied in the luminance-unchanged setup. Whether pupillary responses triggered by global luminance changes modulate saccadic behavior are yet to be explored. Through varying background luminance level in an interleaved pro-and anti-saccade paradigm, we investigated the modulation of pupillary luminance responses on the generation of reflexive and voluntary saccades. Subjects were instructed to either automatically look at the peripheral stimulus (pro-saccade) or to suppress the automatic response and voluntarily look in the opposite direction from the stimulus (anti-saccade). Level of background luminance was increased (light), decreased (dark), or unchanged (control) during the instructed fixation period. Saccade reaction time distributions of correct pro-and anti-saccades in the light and dark conditions were differed significantly from those in the control condition. Moreover, the luminance condition modulated saccade kinematics, showing reduced performances in the light condition than in the control condition, particularly in pro-saccades. Modeling results further suggested that both pupil diameter and pupil size derivative significantly modulated saccade behavior, though effect sizes were small and mainly mediated by intersubject differences. Together, our results demonstrated the influence of pupillary luminance responses on the generation of pro-and anti-saccades.

Differentiating global luminance, arousal and cognitive signals on pupil size and microsaccades

“…The pupil responds to affective and cognitive signals, in addition to its well‐known modulation by global luminance signals (Barbur et al, 1992; Cherng, Crevecoeur, & Wang, 2021; Loewenfeld, 1999; McDougal & Gamlin, 2015; Wang, Tworzyanski, et al, 2018). Larger pupil size is often obtained with higher levels of affective or cognitive processing (Bradley et al, 2008; Janisse, 1973; Kashihara et al, 2014; Morad et al, 2000; Oliva & Anikin, 2018; Partala & Surakka, 2003).…”

Pupil dynamics: A potential proxy of neural preparation for goal‐directed eye movement

“…Therefore, it may be natural that the nonselective attention modulates visually evoked pupillary constriction or dilation and movement latency. Pre‐target pupil dilation of greater magnitude in effortful anti‐saccade task accompanied saccades with shorter latency (Wang et al, 2015) and larger pupil size prior to the target appearance accompanied slightly longer pro‐saccade latencies (Cherng et al, 2020). Similarly, in a recent study on perceptual decision making, the average latency of a button press was greater when the baseline (i.e., before onset of the visual decision cue) pupil size was larger indicating a higher tonic baseline arousal level.…”

Investigating the role of human frontal eye field in the pupil light reflex modulation by saccade planning and working memory

“…Twenty-eight healthy participants (8 males, mean age: 28.1, SD: 3.8 years) from Taipei Medical University were recruited, who were the same participants of another study ( Hsu et al, 2021a ). Sample sizes were chosen based on our previous studies with comparable pupillary and saccadic responses and trial numbers per participant ( Wang et al, 2018 ; Hsu et al, 2020 , 2021a ; Cherng et al, 2021 ). Participants had normal or corrected-to-normal vision and were naïve regarding the purpose of the experiment.…”

“…Statistical tests were performed using ( JASP Team, 2019 ) and MATLAB (The MathWorks Inc., Natrick, MA, USA). Furthermore, following our previous pupil research ( Cherng et al, 2021 ; Hsu et al, 2021a ; Wang et al, 2021 ), we used a linear mixed model (LMM) to examine the impact of cTBS and other factors on the pupil constriction response that allowed us to include these variables as fixed effects while taking inter-participant variability into account ( Pinheiro and Bates, 2000 ).…”