scholarly journals The eyes have it: The pupillary light response as a physiological index of aphantasia, sensory and phenomenological imagery strength

2021 ◽  
Author(s):  
Lachlan Kay ◽  
Rebecca Keogh ◽  
Thomas Andrillon ◽  
Joel Pearson
Keyword(s):  
Recent Work ◽  
Cognitive Functions ◽  
Visual Imagery ◽  
Physiological Response ◽  
Light Response ◽  
Objective Measures ◽  
Light Responses ◽  
Physiological Index ◽  
Pupillary Light ◽  
Sensory Imagery

The pupillary light response is an important automatic physiological response that optimises light reaching the retina. Recent work has shown that the pupil also adjusts in response to illusory brightness and a range of cognitive functions, however, it remains unclear what exactly drives these endogenous changes. Here we show that the imagery pupillary light response correlates with objective measures of sensory imagery strength. Further, the trial-by-trial phenomenological vividness of visual imagery is tracked by the imagery pupillary light response. We also demonstrated that there was no evidence for an imagery pupillary light response in a group of individuals without visual imagery (aphantasia), however, they did show perceptual pupil light responses and pupil dilation with larger cognitive load. Our results provide evidence that the pupillary light response indexes the sensory strength of visual imagery and also provides the first physiological validation of aphantasia.

scholarly journals Living in Biological Darkness: Objective Sleepiness and the Pupillary Light Responses Are Affected by Different Metameric Lighting Conditions during Daytime

2019 ◽  
Vol 34 (4) ◽  
pp. 410-431 ◽  
Author(s):  
Jan de Zeeuw ◽  
Alexandra Papakonstantinou ◽  
Claudia Nowozin ◽  
Sophia Stotz ◽  
Mandy Zaleska ◽  
...  
Keyword(s):  
Light Exposure ◽  
Light Condition ◽  
Light Response ◽  
Light Spectrum ◽  
Light Responses ◽  
Lighting Condition ◽  
Lighting Conditions ◽  
Pupillary Light ◽  
Light Effects ◽  
Dim Light

Nighttime melatonin suppression is the most commonly used method to indirectly quantify acute nonvisual light effects. Since light is the principal zeitgeber in humans, there is a need to assess its strength during daytime as well. This is especially important since humans evolved under natural daylight but now often spend their time indoors under artificial light, resulting in a different quality and quantity of light. We tested whether the pupillary light response (PLR) could be used as a marker for nonvisual light effects during daytime. We also recorded the wake electroencephalogram to objectively determine changes in daytime sleepiness between different illuminance levels and/or spectral compositions of light. In total, 72 participants visited the laboratory 4 times for 3-h light exposures. All participants underwent a dim-light condition and either 3 metameric daytime light exposures with different spectral compositions of polychromatic white light (100 photopic lux, peak wavelengths at 435 nm or 480 nm, enriched with longer wavelengths of light) or 3 different illuminances (200, 600, and 1200 photopic lux) with 1 metameric lighting condition (peak wavelength at 435 nm or 480 nm; 24 participants each). The results show that the PLR was sensitive to both spectral differences between metameric lighting conditions and different illuminances in a dose-responsive manner, depending on melanopic irradiance. Objective sleepiness was significantly reduced, depending on melanopic irradiance, at low illuminance (100 lux) and showed fewer differences at higher illuminance. Since many people are exposed to such low illuminance for most of their day—living in biological darkness—our results imply that optimizing the light spectrum could be important to improve daytime alertness. Our results suggest the PLR as a noninvasive physiological marker for ambient light exposure effects during daytime. These findings may be applied to assess light-dependent zeitgeber strength and evaluate lighting improvements at workplaces, schools, hospitals, and homes.

scholarly journals Altered pupillary light response scales with disease severity in migrainous photophobia

Cephalalgia ◽  
2017 ◽  
Vol 37 (8) ◽  
pp. 801-811 ◽  
Author(s):  
Melissa M Cortez ◽  
Natalie A Rea ◽  
Lindsay A Hunter ◽  
Kathleen B Digre ◽  
KC Brennan
Keyword(s):  
Disease Severity ◽  
Pupil Size ◽  
Light Response ◽  
Light Sensitivity ◽  
Light Responses ◽  
Headache Severity ◽  
Pupillary Light ◽  
Affective Symptoms ◽  
Infrared Pupillometry ◽  
Diameter Change

Background Autonomic dysfunction and light sensitivity are core features of the migraine attack. Growing evidence also suggests changes in these parameters between attacks. Though sensory and autonomic responses likely interact, they have not been studied together across the spectrum of disease in migraine. Methods We performed digital infrared pupillometry while collecting interictal photophobia thresholds (PPT) in 36 migraineurs (14 episodic; 12 chronic; 10 probable) and 24 age and sex-matched non-headache controls. Quantitative pupillary light reflexes (PLR) were assessed in a subset of subjects, allowing distinction of sympathetic vs parasympathetic pupillary function. A structured questionnaire was used to ascertain migraine diagnosis, headache severity, and affective symptoms. Results Photophobia thresholds were significantly lower in migraineurs than controls, and were lowest in chronic migraine, consistent with a disease-related gradient. Lower PPT correlated with smaller dark-adapted pupil size and larger end pupil size at PPT, which corresponded to a reduced diameter change. On PLR testing, measures of both parasympathetic constriction and sympathetic re-dilation were reduced in migraineurs with clinically severe migraine. Conclusions In summary, we show that severity of photophobia in migraine scales with disease severity, in association with shifts in pupillary light responses. These alterations suggest centrally mediated autonomic adaptations to chronic light sensitivity.

scholarly journals RdgB2 is required for dim-light input into intrinsically photosensitive retinal ganglion cells

2015 ◽  
Vol 26 (20) ◽  
pp. 3671-3678 ◽  
Author(s):  
Marquis T. Walker ◽  
Alan Rupp ◽  
Rebecca Elsaesser ◽  
Ali D. Güler ◽  
Wenlong Sheng ◽  
...  
Keyword(s):  
Ganglion Cells ◽  
Light Response ◽  
Amacrine Cells ◽  
Bipolar Cells ◽  
Retinal Ganglion ◽  
Light Conditions ◽  
Light Responses ◽  
Pupillary Light ◽  
Dim Light ◽  
Light Input

A subset of retinal ganglion cells is intrinsically photosensitive (ipRGCs) and contributes directly to the pupillary light reflex and circadian photoentrainment under bright-light conditions. ipRGCs are also indirectly activated by light through cellular circuits initiated in rods and cones. A mammalian homologue (RdgB2) of a phosphoinositide transfer/exchange protein that functions in Drosophila phototransduction is expressed in the retinal ganglion cell layer. This raised the possibility that RdgB2 might function in the intrinsic light response in ipRGCs, which depends on a cascade reminiscent of Drosophila phototransduction. Here we found that under high light intensities, RdgB2− /− mutant mice showed normal pupillary light responses and circadian photoentrainment. Consistent with this behavioral phenotype, the intrinsic light responses of ipRGCs in RdgB2− /− were indistinguishable from wild-type. In contrast, under low-light conditions, RdgB2− /− mutants displayed defects in both circadian photoentrainment and the pupillary light response. The RdgB2 protein was not expressed in ipRGCs but was in GABAergic amacrine cells, which provided inhibitory feedback onto bipolar cells. We propose that RdgB2 is required in a cellular circuit that transduces light input from rods to bipolar cells that are coupled to GABAergic amacrine cells and ultimately to ipRGCs, thereby enabling ipRGCs to respond to dim light.

scholarly journals Melanopsin- and L-cone–induced pupil constriction is inhibited by S- and M-cones in humans

2018 ◽  
Vol 115 (4) ◽  
pp. 792-797 ◽  
Author(s):  
Tom Woelders ◽  
Thomas Leenheers ◽  
Marijke C. M. Gordijn ◽  
Roelof A. Hut ◽  
Domien G. M. Beersma ◽  
...  
Keyword(s):  
Ganglion Cells ◽  
Brightness Discrimination ◽  
Light Response ◽  
Inhibitory Input ◽  
Human Retina ◽  
Constant Intensity ◽  
Light Responses ◽  
Pupillary Light ◽  
Pupillary Constriction ◽  
Pupil Constriction

The human retina contains five photoreceptor types: rods; short (S)-, mid (M)-, and long (L)-wavelength–sensitive cones; and melanopsin-expressing ganglion cells. Recently, it has been shown that selective increments in M-cone activation are paradoxically perceived as brightness decrements, as opposed to L-cone increments. Here we show that similar effects are also observed in the pupillary light response, whereby M-cone or S-cone increments lead to pupil dilation whereas L-cone or melanopic illuminance increments resulted in pupil constriction. Additionally, intermittent photoreceptor activation increased pupil constriction over a 30-min interval. Modulation of L-cone or melanopic illuminance within the 0.25–4-Hz frequency range resulted in more sustained pupillary constriction than light of constant intensity. Opposite results were found for S-cone and M-cone modulations (2 Hz), mirroring the dichotomy observed in the transient responses. The transient and sustained pupillary light responses therefore suggest that S- and M-cones provide inhibitory input to the pupillary control system when selectively activated, whereas L-cones and melanopsin response fulfill an excitatory role. These findings provide insight into functional networks in the human retina and the effect of color-coding in nonvisual responses to light, and imply that nonvisual and visual brightness discrimination may share a common pathway that starts in the retina.

The pupillary light response reflects encoding, but not maintenance, in visual working memory.

2016 ◽  
Vol 42 (11) ◽  
pp. 1716-1723 ◽  
Author(s):  
Tessel Blom ◽  
Sebastiaan Mathôt ◽  
Christian N. L. Olivers ◽  
Stefan Van der Stigchel
Keyword(s):  
Working Memory ◽  
Visual Working Memory ◽  
Light Response ◽  
Pupillary Light

scholarly journals Deep learning-based pupil model predicts time and spectral dependent light responses

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Babak Zandi ◽  
Tran Quoc Khanh
Keyword(s):  
Deep Learning ◽  
Time Course ◽  
Light Response ◽  
Absolute Error ◽  
Light Responses ◽  
Temporal Prediction ◽  
Feed Forward Neural Networks ◽  
Self Learning ◽  
Pupil Light Response ◽  
Planckian Locus

AbstractAlthough research has made significant findings in the neurophysiological process behind the pupillary light reflex, the temporal prediction of the pupil diameter triggered by polychromatic or chromatic stimulus spectra is still not possible. State of the art pupil models rested in estimating a static diameter at the equilibrium-state for spectra along the Planckian locus. Neither the temporal receptor-weighting nor the spectral-dependent adaptation behaviour of the afferent pupil control path is mapped in such functions. Here we propose a deep learning-driven concept of a pupil model, which reconstructs the pupil’s time course either from photometric and colourimetric or receptor-based stimulus quantities. By merging feed-forward neural networks with a biomechanical differential equation, we predict the temporal pupil light response with a mean absolute error below 0.1 mm from polychromatic (2007 $$\pm$$ ± 1 K, 4983 $$\pm$$ ± 3 K, 10,138 $$\pm$$ ± 22 K) and chromatic spectra (450 nm, 530 nm, 610 nm, 660 nm) at 100.01 ± 0.25 cd/m2. This non-parametric and self-learning concept could open the door to a generalized description of the pupil behaviour.

Nervous control of light responses in the sea anemone, Calamactis praelongus

1976 ◽  
Vol 65 (1) ◽  
pp. 85-96
Author(s):  
P. S. Marks
Keyword(s):  
Light Response ◽  
Sea Anemone ◽  
Light Stimulation ◽  
Local Effects ◽  
Nervous Control ◽  
Light Responses ◽  
Nerve Net ◽  
Muscular Responses

1. The burrowing sea anemone, Calamactis praelongus, responds to light with local, non-nervous contractions of the column. There are also more extensive responses of the column and retractor muscles co-ordinated by nerve net pulses (NNP's) under pacemaker control. 2. NNP's occur in at least two types of bursts and in sequences which sometimes indicate a rotating site of pulse initiation. 3. Light-evoked NNP sequences can be tape recorded and used later to drive a stimulator to reproduce the original sequences in the same or different anemones, evoking muscular responses which approximate the originals. This technique separates the pacemaker-directed component of the light response from the local effects of light stimulation. 4. Isolated circular and parietal muscles contract slowly when stimulated by light or excited indirectly by NNP's. Retractor muscles are insensitive to light but produce rapid contractions when excited by closely spaced light-evoked NNP's. 5. A model for light responses is proposed which incorporates the characteristics of isolated muscles and intact anemones.

Dual effect of glycine on horizontal cells of the tiger salamander retina

1991 ◽  
Vol 66 (6) ◽  
pp. 1993-2001 ◽  
Author(s):  
S. Borges ◽  
M. Wilson
Keyword(s):  
Opposite Effect ◽  
Horizontal Cell ◽  
Light Response ◽  
Membrane Resistance ◽  
Horizontal Cells ◽  
Field Size ◽  
Dual Effect ◽  
Light Responses ◽  
Low Concentrations ◽  
High Concentrations

1. The effects of glycine on horizontal cells have been examined by microelectrode recording from superfused retinas isolated from the salamander. 2. Low concentrations of glycine (less than 50 microM) hyperpolarized horizontal cells and increased the magnitude of their light responses. Millimolar concentrations produced the opposite effect of depolarizing these cells and reducing their light response amplitudes. 3. In the presence of Co2+ and Mg2+ at concentrations sufficient to suppress the light response, millimolar glycine still exerted a depolarizing effect on horizontal cells, implying that this effect was largely a direct one on horizontal cell membranes. 4. Although both the rod and the cone contributions to horizontal cell light responses were reduced by millimolar glycine, rod input was reduced more, suggesting that millimolar glycine may also exert a presynaptic effect. 5. Strychnine (10 microns) antagonized the effects of millimolar glycine and, in the absence of exogenously applied glycine, caused horizontal cells to hyperpolarize and their light responses to increase in amplitude. This result implies that, in darkness, glycine is tonically released onto horizontal cells and maintains them in a state of partial depolarization. 6. The low-concentration effect of glycine was accompanied by an increased membrane resistance and receptive field size but no change in the balance of rod and cone input. 7. Low concentrations of glycine were often seen to cause a speeding of light responses, whereas high concentrations sometimes caused a slowing of response kinetics. Response kinetics were found to correlate with horizontal cell dark membrane potential so that, positive to -30 mV, depolarization slowed responses whereas kinetics at more negative values were largely independent of voltage.

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