News tagged with eye

Related topics: brain · nerve cells · current biology · retina

Why we can't tickle ourselves

Some of us are more ticklish than others, but nearly everyone is unable to tickle themselves. The answer is tied to how we see and how we perceive movement.

May 23, 2016
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Case of palytoxin-related keratitis described

(HealthDay)—In a letter to the editor published online April 30 in Clinical and Experimental Ophthalmology, unilateral palytoxin-induced chemical keratitis is described after a coral expressed its toxin into the patient's ...

May 09, 2016
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Eye

Eyes are organs that detect light, and send signals along the optic nerve to the visual and other areas of the brain[citation needed]. Complex optical systems with resolving power have come in ten fundamentally different forms, and 96% of animal species possess a complex optical system. Image-resolving eyes are present in cnidaria, molluscs, chordates, annelids and arthropods.

The simplest "eyes", such as those in unicellular organisms, do nothing but detect whether the surroundings are light or dark, which is sufficient for the entrainment of circadian rhythms. From more complex eyes, retinal photosensitive ganglion cells send signals along the retinohypothalamic tract to the suprachiasmatic nuclei to effect circadian adjustment.

This text uses material from Wikipedia, licensed under CC BY-SA

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