Scientists discovered that fruit flies store memories using postsynaptic changes at cholinergic synapses, similar to how humans use postsynaptic mechanisms at glutamate synapses. Specific acetylcholine receptor subunits (α5 and α2) in brain cells called M4/6 neurons are required for different stages of memory formation. The research shows that fundamental memory storage mechanisms are conserved across evolution despite differences in the chemical messengers used.