You’ve All Seen Them: Phosphenes

What are phosphenes?

The other day, a former student of mine contacted me and wanted to know if I could explain to him what phosphenes were. He had recently come across that term, when he had tried to find an explanation for the coloured patterns that had appeared “in his head”, even though his eyes had been closed. The term ‘phosphene’ combines the Greek words ‘phos’ (= light) and ‘phainein’ (= to show) or ‘phenomenon’ and refers to images that are generated in the brain and that people “see” with closed eyes. The images are not stationary and usually consist of wavy, circular, striped or rapidly changing and usually multi-coloured cloud-like patters that can be frighteningly intense and may, in the past, have been the explanations for the visions that religious mystics have reported.

Visual patterns of these kinds are apparently more frequently experienced by children than adults, but they can and do occur in anyone’s brain and are likely to be present also in animals. But what are they, what causes them and how can their “existence” be proven, let alone be explained? They cannot, after all, be photographed, measured or counted.   – and yet, we do know they exist and manifest themselves in the sensations we describe as phosphenes. Following the publication of my 2009 book “Bioluminescence in Focus  – a collection of illuminating essays”, which contained one chapter on ultraweak photo emissions by Dr Bajpai, the Hungarian phosphene researcher Dr. István Bókkon approached me and we exchanged some ideas.

According to Bókkon the visual sensation of phosphenes is due to the intrinsic perception of ultraweak bioluminescent photon emissions. That biophotons are ‘real’ and do exist in all living organisms is an undisputed fact (and one of my blogs was devoted to them: “Biophotons do exist, but then so what?“), but questions as to their generation, role and indeed perception are still largely unanswered. Phosphenes can occur randomly, but are readily inducible by pressure (for example a blow on the head or a punch in the eye, causing the injured “to see stars”), by electrical and transcranial magnetic field stimulation, by psychotic conditions, and certain diseases (migraine for instance) and, of course, by innumerable drugs (such as nicotine, cocaine, amphetamine, morphine, etc.) as well as alcohol. All these different forms of stimulation, according to Bókkon, lead to oxidative damage and the production of free radicals and their cellular effects on lipid peroxidation, mitochondrial respiration, oxidation of the amino acids tyrosine and tryptophane residues in proteins. 

Electrical brain stimulation of the visual cortex with a few micro- to milli-amperes with electrodes were able to elicit phosphenes in sighted as well as blind people and since the brain does indeed generate ultraweak biophotons, the question is whether the amount and production of such biophotons are affected by the stimulation and whether the biophotons can be perceived. Bókkon suggests that the biochemical reactions elicited by the various forms of stimulation lead to an uncontrolled overproduction of free radicals, which are the main source of the ultraweak photon emissions, but depend on the neural activity and oxygen concentration in the brain. In several regions of the brain, the cerebral cortex, the pineal, the cerebellum, etc, molecules are present that can interact with the biophotons, thereby causing the sensation of phosphenes. He points out that opsins are not just the rhodopsin (i.e., the visual pigment in photoreceprive cells of our eye’s retina, giving us “vision”), but that multiple kinds of opsins, for example encephalopsin, neuropsins, etc. (all capable of interacting with photons), have been detected in multiple regions of the brain. 


Although undoubtedly a part of a human brain’s activity and function, phosphenes are difficult to investigate. We know they are there and can be generated, but to experimentally manipulate them, to quantitatively record and analyse them, still poses challenges that need to be mastered before one can assign a functional role to them, which according to some could eventually lead to “mind-to-mind communication technology” and help the blind to “see”. Wishful thinking? Who knows.  

© Dr V.B. Meyer-Rochow and http://www.bioforthebiobuff.wordpress.com, 2022. Unauthorized use and/or duplication of this material without express and written permission from this site’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to V.B Meyer-Rochow and http://www.bioforthebiobuff.wordpress.com with appropriate and specific direction to the original content.

Lowering their Heads and Facing East

Why do sunflowers behave this way?

Anyone who undertakes a train journey in late summer from Helsinki to Beijing (like I did quite some years ago), will see extensive fields of sunflowers before the train leaves Europe and enters Asian territory. What is remarkable about the sunflowers is that they all face one direction and observing that, I thought the sunflowers probably orient themselves towards the sun. But according to a recent study by Horvath and co-workers, this is not so, because following a short period of full bloom during which the flowers do orient towards the sun, they then gradually bend downward and become ‘locked’ in a direction to face the East. (Now the beautiful and patriotic song “The East is Red” 东方红, never mind the words, enters my head and reminds me of the time I heard it daily while spending 3 weeks in China by invitation of the Chinese Academy: you can guess how long ago that must’ve been!). However, sunflowers, which like many fruit and vegetable plants originated in the ‘New World’, have other reasons to turn eastward.

In the past, several reasons had been advanced to explain why after the flowering period sunflower inflorescences no longer track the sun, but remain east-oriented. Yet none have been tested reliably and the new explanation for the first time takes into consideration the place of origin of the sunflower plant, the astronomical data of the sun’s position, the meteorological data of diurnal cloudiness, the time-dependent elevation angle of mature sunflower heads and the absorption spectra of the inflorescence’s front and back. An earlier suggestion was that a non-skyward orientation of mature sunflower heads would make it more difficult for birds to peck at the seeds. While true, it does not explain why the flowers should face east. Another attempt to explain the eastward orientation was that it would reduce the heat load at noon, but west-facing flowers would have the same advantage, so why ‘east’? It has also been assumed that east-facing allows greater light reception in the morning and speeds up drying of morning dew, thereby reducing fungal attack. That an easterly orientation promotes attractiveness to pollinators has been suggested, but by the time the sunflower heads get ‘locked’ in the easterly position, pollination has long been finished and the idea that an easterly orientation and the lower head temperature could be advantageous for seed maturation was not supported experimentally.

What appears to be crucial is that there is a 10-50% surplus energy absorbed by an east-facing sunflower inflorescence compared with other directional orientations. This could indeed accelerate the evaporation of morning dew, but what is the easterly orientation due to? It has seemingly something to do with the region the sunflower plant evolved, namely Boone County in North America, which regularly encounters cloudy afternoons. If afternoons are cloudier than the mornings, then east-facing inflorescences have an energy advantage of around 10% over west-facing flowers and an up to 50% radiation excess over south-facing flowers, taking into consideration absorption spectra of the inflorescence and the back of the heads. Maximum radiation absorption should be advantageous for seed production and maturation. The easterly orientation seen even in domesticated European sunflowers is likely to be a genetic trait that evolved in response to the meteorologic conditions of cloudy afternoons in the region that sunflowers evolved in North America.

Given that solar panels are usually directed south and direct sunlight is most intense at noon, are sunflowers ill-adapted, or do sunflowers perhaps ‘know more’ than solar panel engineers? Sunflower heads are tilted, looking downward and under such conditions the lower angle of the sun in westerly and easterly position is crucially important. But adding afternoon cloudiness into the calculation is what then causes the East to turn into ‘the winning formula’ for Helianthus annuus (the sunflower).

© Dr V.B. Meyer-Rochow and http://www.bioforthebiobuff.wordpress.com, 2021.
Unauthorized use and/or duplication of this material without express and written permission from this site’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to V.B Meyer-Rochow and http://www.bioforthebiobuff.wordpress.com with appropriate and specific direction to the original content.

biology zoology blog benno meyer Making Sense of Sensors

Making Sense of Sensors

The Laws of Weber-Fechner and Bloch

Of the courses I teach, I love “Animal Senses and Behaviour” the most. A study of behaviour does not make much sense to me, unless we first examine how an individual detects a stimulus and that requires some knowledge about the sensory structures involved, namely their anatomical organization and their physiological (= functional) properties plus the nerve centres involved in processing. In this context the meaning of two so-called “laws”, known as Weber-Fechner Law and Bloch’s Law, are important. —>—>