For more than a century, neuroscience has been built around a neuron-centered worldview. The heroes of this story are familiar neurotransmitters: dopamine, serotonin, norepinephrine, acetylcholine, glutamate, and GABA. Textbooks describe neurons communicating across synapses in brain circuits using these specialized chemical messengers. The vast ‘connectome’ network of axons and dendrites was believed to determine mental events. Neurons were viewed as the only true informatio