The Song of the Cell: An Exploration of Medicine and the New Human

by Siddhartha Mukherjee

Serotonin, Greengard and other researchers had found, doesn’t only act as a “fast” neurotransmitter, and depression isn’t just a malfunctioning neuronal circuit that can be reset by increasing serotonin in the synapse. Rather, serotonin sets off a “slow” signal in neurons—biochemical signals that come on cat’s feet—including altering the activity and function of several intracellular proteins that Greengard’s lab had identified. Paul believes that these proteins, which modify neuronal activity, are crucial to the slow signaling in neurons that regulate mood and emotional homeostasis. In his earlier work, he had shown that one such factor, called DARPP-32, is critically responsible to the way a neuron responds to another transmitter, called dopamine, which is involved in many other neurological functions, including our mind’s response to reward and addiction.