Despite science having gone quite a long way these past few decades, researchers keep discovering new stuff that surprises and baffles them, including the fact that human brains emit a strange glow – that they can’t understand why.
Indeed, scientists have for the first time ever measured the brain’s faint glow, indicating a possible role of biophotons in cognition in what they refer to as ultraweak photon emissions (UPEs), according to a report by Scientific American published on June 16.
As it happens, life forms can generate their own light, ranging from the bioluminescence of glowworms and lamp-headed anglerfish and heat-induced radiation, all the way to these UPEs, where living tissues emit a continuous stream of low-intensity light or biophotons.
Why your brain is glowing – maybe
Researchers believe this light stems from energy-generating biomolecular reactions, creating photons as by-products. Furthermore, the more energy a tissue burns, the more light it produces, which means our brain should glow the brightest among all our body’s tissues.
Per the most recent study in this particular area, researchers detected biophotons emitted by the human brain from outside the skull for the first time in history. Interestingly, these emissions varied when participants carried out different cognitive tasks.
That said, the exact relationship between our brain’s activity and these variable photonic emissions has largely remained a mystery. In the view of the study’s authors, these particles of light may play a deeper role in the brain, which they have yet to uncover.
Notably, all matter emits photons due to having a temperature above absolute zero and radiating photons as heat, often with longer wavelengths than we can witness with our eyes. UPEs are more intense than this, their wavelengths in the visible or near-visible light range of the electromagnetic spectrum.
Considering the fact that living cells generate energy through metabolism, they produce oxygen molecules with excited electrons as by-products. When these electrons go back to a lower energy state, they produce photons in what is called radiative decay.
From a few photons to several hundred of them per square centimeter each second, researchers have been able to detect this radiative decay as a weak but steady stream of light through their study of biological tissues, including neurons in Petri dishes.
According to Nirosha Murugan, a physicist at Wilfrid Laurier University in Ontario and the study’s senior author:
“Scaling this up to humans, we wanted to know if those photons might be involved in some information processing or propagation [in the brain].”
Testing the brain glow
To this end, they brought 20 participants to a blacked-out room, fitted them with head caps studded with electroencephalography (EEG) electrodes to measure the brain’s electrical activity, and applied photon-amplifying tubes to detect UPEs around their heads.
They clustered these detectors over two brain regions – the occipital lobes in the back of the brain, responsible for visual processing, and the temporal lobes on each side of the brain, responsible for auditory processing. The researchers also placed separate UPE detectors facing away from the participants.
In Murugan’s words, “The very first finding is that photons are coming out of the head – full stop. It’s independent, it’s not spurious, it’s not random.”
Then, they tested how the intensity of these emissions changed depending on the nature of the cognitive task the participants were performing. As opposed to neurons in a dish and despite the brain being a metabolically intensive organ, UPE intensity didn’t increase.
On the other hand, the team did discover that the UPE signals would change only when participants switched cognitive tasks, like opening and closing their eyes, which indicates some sort of a link between brain processing and the biophotons it releases.
Commenting on this, Michael Gramlich, a biophysicist at Auburn University, who was not involved in the new study, said:
“I think this is a very intriguing and potentially groundbreaking approach [for measuring brain activity, though] there are still many uncertainties that need to be explored. (…) The essential question to address [is whether] UPEs are an active mechanism to alter cognitive processes or if UPEs simply reinforce more traditional mechanisms of cognition.”
In the future, Murugan and her team plan to use more precise sensor arrays to discover where in the brain these photons are coming from. They also hope to turn photoencephalography into a useful way to noninvasively measure brain states one day.
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