A role for serotonin in long-term memory

Yale scientists have discovered a new mechanism for strengthening synapses that store long-term memories. Applying the neurotransmitter serotonin to pre-synaptic and post-synaptic cells in the sea slug Aplysia strengthened the synapse if both cells received the serotonin within 15 minutes of each other. Researchers had previously determined that serotonin, which is linked to aggression and depression in mammals, also would strengthen synapses when applied in sufficient quantities to pre-synaptic cells. In the more recent experiments, the researchers applied to both pre-synaptic and post-synaptic cells amounts of serotonin too small to induce long-term memory when applied to one cell alone. “It’s a new way of signal processing within a cell that is different than what we had thought of before,” said neurobiologist Carolyn Sherff, Ph.D., a postdoctoral associate and co-author of the study with Thomas Carew, Ph.D., professor of psychology and molecular, cellular and developmental biology. Their study was published Sept. 17 in the journal Science.