ON and OFF visual pathways in vertebrates first appeared during the Cambrian period

Retinal ON and OFF bipolar cells, along with novel metabotropic glutamate receptors, are present in lamprey.

• The study identifies the presence of distinct ON and OFF bipolar cells in lamprey.
• Novel metabotropic glutamate receptors are found on the dendrites of ON bipolar cells.
• The findings suggest that separate ON and OFF visual pathways may have originated in the vertebrate visual system over 500 million years ago during the late Cambrian.

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