This book focuses in the most recent findings regarding electrical synapses in the spinal cord circuitry, we review from the mechanisms of presynaptic inhibition of sensory reflexes, distribution of electrical synapses in motoneurones and spinal interneurones, to the role of electrical synapses in spinal function and possible implications for primary afferent processing. The introduction will guide you through the history on the discoveries of electrical and synaptic transmission in the spinal cord and how these important findings have shaped our most recent ideas on electrical transmission in the adult spinal cord.