Certain synapses strengthen upon coincident secretion of the neurotransmitter glutamate from a neighboring astrocyte, suggesting that astrocytes contribute to learning.

A light-activated enzyme with a flavin chromophore is found in several bacterial species, and in one of these it regulates light-stimulated macrophage infection.

Visual and sensory stimuli that mimic subjects viewing themselves from a distance produced a center of awareness (or sense of self) outside their bodies.