Chemical synapses also serve to amplify neuronal signals, so that even a small presynaptic nerve terminal can alter the response of a large postsynaptic cell.
As for ultrastructure, quantitative analysis showed that NPY-IR amacrine cell processes were most often presynaptic to NPY negative amacrine cell processes (49.7%) and ganglion cell dendrites (49.3%).
Recently, transporter, that is a sort of protein located in the presynaptic membrane, vesicle membrane and glia cell membrane, has been the study hotspot of neuroscience.