Peysakhovich Vsevolod, Vachon François, Dehais Frédéric
ISAE-SUPAERO, Université de Toulouse, Toulouse, France.
Ecole de Psychology, Université Laval, Québec, Canada.
Int J Psychophysiol. 2017 Feb;112:40-45. doi: 10.1016/j.ijpsycho.2016.12.003. Epub 2016 Dec 12.
Pupillary reactions independent of light conditions have been linked to cognition for a long time. However, the light conditions can impact the cognitive pupillary reaction. Previous studies underlined the impact of luminance on pupillary reaction, but it is still unclear how luminance modulates the sustained and transient components of pupillary reaction - tonic pupil diameter and phasic pupil response. In the present study, we investigated the impact of the luminance on these two components under sustained cognitive load. Fourteen participants performed a novel working memory task combining mathematical computations with a classic n-back task. We studied both tonic pupil diameter and phasic pupil response under low (1-back) and high (2-back) working memory load and two luminance levels (gray and white). We found that the impact of working memory load on the tonic pupil diameter was modulated by the level of luminance, the increase in tonic pupil diameter with the load being larger under lower luminance. In contrast, the smaller phasic pupil response found under high load remained unaffected by luminance. These results showed that luminance impacts the cognitive pupillary reaction - tonic pupil diameter (phasic pupil response) being modulated under sustained (respectively, transient) cognitive load. These findings also support the relationship between the locus-coeruleus system, presumably functioning in two firing modes - tonic and phasic - and the pupil diameter. We suggest that the tonic pupil diameter tracks the tonic activity of the locus-coeruleus while phasic pupil response reflects its phasic activity. Besides, the designed novel cognitive paradigm allows the simultaneous manipulation of sustained and transient components of the cognitive load and is useful for dissociating the effects on the tonic pupil diameter and phasic pupil response.
长期以来，与光照条件无关的瞳孔反应一直与认知相关联。然而，光照条件会影响认知性瞳孔反应。以往的研究强调了亮度对瞳孔反应的影响，但亮度如何调节瞳孔反应的持续性和瞬态成分——紧张性瞳孔直径和相位性瞳孔反应，仍不清楚。在本研究中，我们调查了在持续认知负荷下亮度对这两个成分的影响。14名参与者执行了一项新颖的工作记忆任务，该任务将数学计算与经典的n-back任务相结合。我们研究了在低（1-back）和高（2-back）工作记忆负荷以及两种亮度水平（灰色和白色）下的紧张性瞳孔直径和相位性瞳孔反应。我们发现，工作记忆负荷对紧张性瞳孔直径的影响受到亮度水平的调节，在较低亮度下，随着负荷增加，紧张性瞳孔直径的增加幅度更大。相比之下，在高负荷下发现的较小的相位性瞳孔反应不受亮度影响。这些结果表明，亮度会影响认知性瞳孔反应——紧张性瞳孔直径（相位性瞳孔反应）在持续（分别为瞬态）认知负荷下受到调节。这些发现还支持了蓝斑系统之间的关系，推测其以紧张性和相位性两种放电模式发挥作用，与瞳孔直径有关。我们认为，紧张性瞳孔直径跟踪蓝斑的紧张性活动，而相位性瞳孔反应反映其相位性活动。此外，所设计的新颖认知范式允许同时操纵认知负荷的持续性和瞬态成分，并且有助于区分对紧张性瞳孔直径和相位性瞳孔反应的影响。
