The eyes have a surprise.
For decades, biology textbooks have stated that eyes communicate with the brain exclusively through one type of signaling pathway. But a new discovery shows that some retinal neurons take a road less traveled.
New research, led by Northwestern University, has found that a subset of retinal neurons sends inhibitory signals to the brain. Before, researchers believed the eye only sends excitatory signals. (Simply put: Excitatory signaling makes neurons to fire more; inhibitory signaling makes neurons to fire less.)
The Northwestern researchers also found that this subset of retinal neurons is involved in subconscious behaviors, such as synchronization of circadian rhythms to light/dark cycles and pupil constriction to intense bright lights.