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Do Brighter Species’ Brains Emit Redder Light?

Photon emissions in the brain are red-shifted in more-intelligent species, though scientists dispute what that means.

Alison F. Takemura

EXCITED LIGHT: Neurons stimulated with the neurotransmitter glutamate produce biophotons, ultraweak pulses of light. PIXABAY, GDJ

EDITOR'S CHOICE IN NEUROSCIENCE

The paper
Z. Wang et al., “Human high intelligence is involved in spectral redshift of biophotonic activities in the brain,” PNAS, 113:8753–58, 2016.

Brain aglow
Neurons can emit ultraweak photons when stimulated by the abundant neurotransmitter glutamate, and experiments suggest that the emitted light can travel along rat nerve fibers. Yet most researchers don’t believe there’s enough evidence to say whether these so-called biophotons act as communication signals, according to Michal Cifra, who studies the phenomenon at the Institute of Photonics and Electronics in the Czech Academy of Sciences.

Catching some rays
To test for a biological role for biophotons, a team in China analyzed brain slices from six species of roughly increasing intelligence: bullfrog, chicken, mouse, pig, rhesus monkey, and human. The group
doused the tissues with...

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