Monday, 13 July 2015

Why Coloured Patterns and Shapes Appear When We Close Our Eyes?

Introduction

When we close our eyes, we get to see some colourful patterns and shapes coming before us against the dark background. This is commonly known as closed-eye visualization. In scientific circles, it is better referred to as photopsias or phosphenes. This is best explained as sudden bursts of bright colours appearing in all parts of the vision field. This happens when one closes his eyes or enters a dark room. This would have kept us wondering about this. Some people even go panicking about their eyes, thinking that the eyes have gone bad. In this blog, let us see what this phenomenon is all about.


Colourful Patters Before Eyes

The closed-eye visualization happens a person goes into a dark room or closes his eyes. It is called as phosphene. This occurs in different forms. In all, the neurologists and other scientists working on this phenomenon have categorized them into 15 categories. Some of them are quite common in perception when viewed. They usually come in most common categories such as triangles, spirals, stars, amorphous blogs, spots, etc. This phenomenon is primarily due to the emission of photons by normally functional neurons during cell metabolism. Normally, the neurons in thalamus, retina and visual cortex are always active. Hence, they spontaneously fire the photons and activate the neighbouring neurons. As a result of this, the atoms in retina absorb and with a lag re-emit the photons in different wavelengths. This chain absorption and emission gets relayed through different neuron cells to the visual cortex of the brain. Based on the patterns or colours this part of the brain receives, it decides whether it has received the real images or phosphenes. This neural excitation happens even when there is no photon. The nature of phosphenes generated depends upon the place from where the photon was fired. Accordingly, it could take different shapes, colours and patterns. This spontaneous excitation of neurons can happen due to a variety of factors. They are mechanical, magnetic, metabolic and electrical stimulations. Certain drugs, such as psilocybin, LSD, etc., also could make similar stimulations.


How Brain Interprets the Visual or Electrical Signal?

Due to the ongoing cell metabolism, the neurons fire photons that are captured by neighbouring neurons only to re-emit them in different frequencies or wavelengths. This chain of events gets relayed to the visual cortex of the brain in no time. The visual cortex tries to re-construct the image from whatever input it gets from the neurons that feed it. If the image re-constructed does not correspond to a real-time object, the visual cortex labels it as a phosphene. The frequency and colour pattern of emission depends upon the area from where it was fired as previously said. This can be used to state where there is hyperactivity of the neurons and the reason for such behaviour.


Thuruvananthapuram Bengaluru, Karnataka, India