Extraocular Phototransduction: more than meets the eye? (part 2)

Ears_LightWe recently drew attention to the 1998 discovery at Cornell regarding the possibility of tweaking one’s cicadian rhythms by shining a bright light at the back of one’s knees. But continuing research into extraocular (outside the eye) light stimuli has turned to the possibility of a more direct route. Why not shine a light directly into one’s brain? Fortunately, there’s no need to resort to trepanning, because (at least) two convenient pathways already exist for brain illumination. Namely the ear canals. A research team from the University of Oulu, Finland (“Creating Innovation for the Future”) tested volunteers while they underwent blood oxygen level dependent (BOLD) functional magnetic resonance imaging scanning (fMRI) as a bright light was delivered via their external ear canal :

“Light was produced by two 3 W LEDs (main light spectrum peak at blue light 465 nm and a secondary peak at 550 nm) and delivered via 5 meters long polycarbonate colourless fiber optic light guides connected to ear-plugs in the subject’s ears while inside the scanner.”

Findings from the study :

“…suggest that the brain possesses photosensitive properties, which will have interesting implications for the modulation of brain function and understanding the basic physiology of the brain.”

But, the authors add :

“The mechanism for the phototransduction of the brain tissue remains to be discovered and we are currently investigating it in more depth.”

see: ‘Stimulating brain tissue with bright light alters functional connectivity in brain at the resting state’


[1] “ Some of the authors have conflicts of interests with a company, Valkee Ltd., that develops and sells devices for bright light stimulation via ear-canal. Authors’ connections with Valkee Ltd. are: Nissilä and Aunio are company founders. Nissilä, Aunio, Takala and Timonen are share-holders (varying from major to minor). Nissilä, Aunio and live-in partner of Starck are employed by Valkee Ltd. Valkee Ltd. did not have a role in the decision to submit the paper for publication.”

[2] The company, Valkee, has recently received a US patent for their invention ‘Portable Ear Light Device’ and also have a European patent pending for a Device and method for altering dopamine level from which the illustration above is taken.

[3] Many thanks to John Hoyland’s Feedback column in New Scientist, 10 May 2013 ‘Light up your Brain’ for drawing attention to the Valkee ear light.

BONUS : (unrelated, except via wordplay) ‘Me ears are alight’