Synaptic failure was the loss of the synaptic functions of the brain. Following an attack, Vedek Bareil suffered from a synaptic failure and was treated by Doctor Julian Bashir aboard Deep Space 9. He applied direct neuro-stimulation to the brainstem but the left temporal lobe was showing massive signs of synaptic failure. (DS9: "Life Support") Paris experienced in one of his flashbacks that twenty-five microliters of acetylcholine were not helping Ahni Jetal and she got a massive synaptic failure. (VOY: "Latent Image")