Discovery of Neurotransmitters

Otto Loewi's 1921 frog heart experiment definitively proved that neurons communicate via chemical messengers, not just electrical signals. The discovery led to the identification of dopamine, serotonin, GABA, and others, with over 50% of psychiatric drugs today targeting these neurotransmitters. Its foundational role is reflected in more than 20,000 studies involving synaptic transmission, establishing a pillar of modern neuroscience.