soliton: (physics) a quantum of energy or quasiparticle that can be propagated as a traveling wave in nonlinear systems and is neither preceded nor followed by another such disturbance; does not obey the superposition principle and does not dissipate
traveling wave: a wave in which the medium moves in the direction of propagation of the wave
serotonin: a neurotransmitter involved in e.g. sleep and depression and memory