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Cédric Lamirel, Jean-Michel Hupé, Jean Lorenceau; Pupil dynamics during bistable form/motion binding. Journal of Vision 2008;8(6):253. doi: 10.1167/8.6.253.
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© ARVO (1962-2015); The Authors (2016-present)
Endogeneous modification of the perception of otherwise unchanging visual stimuli, so called perceptual bistability, provides a heuristic to uncovering the cerebral networks of consciousness and awareness. Searching for physiological correlates of bistable perception, we recorded pupil variations during perceptual reports of bistable moving stimuli. Our findings reveal a modulation of pupil diameter tightly witnessing perceptual changes and motor decisions. Pupil dilates ∼300 ms before a button press signalling a flip from one perceptual state to another. Pupil dilation thus reflects a, yet unreported, change in phenomenal consciousness. Dissecting the perceptual, decisional, attentional and motor components of pupil activity in additional experiments, we found that the dynamics of pupil dilation is different with endogenously and exogenously driven alternations and has a strong motor component. Pupil diameter being controlled through sympathetic and parasympathetic antagonist activity, pupil dilation thus reveals the implication of subcortical structures during reports of bistable perception and opens a window to studying their activity. As changes in pupil size have the potential to activate retino-cortical pathways through changing retinal illumination, pupil dynamics should be taken into consideration when analysing cerebral activity recorded with imaging techniques, either to ensure that it is not the cause of the recorded signals, and/or to improve the signal-to-noise ratio.
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