Shining of light within the eye causes transmission via the optic nerve to synapse with neurones in the pre-tectal area rostral to the superior collicus (midbrain) forming the afferent pupillary response. One small pupil and one normal-sized one ( anisocoria ) A drooping eyelid. Dilator Pupillae- dilator muscle that is innervated by the sympathetic nervous system Pathway of Pupillary Light Constriction. Some signs to watch for include the following: Two small pupils. The contraction of the sphincter pupillae muscle, which leads to the constriction of the pupil (myosis). The type of symptoms you have can vary depending on what's causing the miosis. The present findings suggested that transient arousal drops, as denoted by the autonomic nervous modulation of pupil size, are involved in inducing the spontaneous perceptual switch of bistable stimuli.Īrousal Autonomic Bistable perception Nervous system Parasympathetic pathway Pupillometry.Ĭopyright © 2021 The Authors. Detecting whether you have a constricted pupil may or may not be obvious. The constriction of pupil occurs due to contraction of sphincter pupillae muscle and relaxation of dilator pupillae muscle. Furthermore, rapid pupil dilations with behavioral response are also mediated by the peripheral parasympathetic pathway. Pharmacological experiments confirmed that the pupil constriction disappeared when the peripheral parasympathetic pathway (pupil sphincter muscle) was blocked, but it remained intact when the peripheral sympathetic pathway (pupil dilator muscle) was manipulated. In the dark, they open wider or dilate to let in more light in bright light, they get smaller or constrict to prevent too much light from getting in. Since these muscles are innervated by the parasympathetic and sympathetic nervous systems, respectively, different parameters of the PLR can be used as indicators for either sympathetic or.

Such pupil constriction was not observed before the exogenous perceptual switch. The pupillary light reflex (PLR) describes the constriction and subsequent dilation of the pupil in response to light as a result of the antagonistic actions of the iris sphincter and dilator muscles. Here, we show that the pupils shrank a few seconds prior to the onset of the spontaneous perceptual switch. We hypothesized that increased fluctuations in spontaneous neural activity due to arousal reduction drive the perceptual switch.

However, it remains unclear what drives a spontaneous perceptual alteration. Perceptual rivalry of ambiguous stimuli reflects the interaction of neural activity among multiple cortical regions.

Constriction of pupil muscle