Axo-axonic synapse
An axo-axonic synapse is a type of synapse, formed by one neuron projecting its axon terminals onto another neuron's axon.
from Wikipedia
軸索(Axon)どうしのシグナル伝達
樹状突起(Dendrite)どうしの場合はDendrodendritic synapse
化学シナプス(Chemical synapse)
電気シナプス(Electrical synapse)