Probing synaptic signaling with quantum dots.

Synapses are the principal substrates of neuronal communication in the brain. Neuroscientists are trying to understand how the remodeling of synapses at the molecular level leads to changes in learning and memory. The lateral movement of neurotransmitter receptors is emerging as an important mechanism in the control of synaptic transmission. However, our understanding of the spatial dynamics of membrane receptors at synapses has been limited largely because of a lack of appropriate tools to resolve single receptors in living cells. Fluorescent quantum dots represent promising probes to monitor individual synaptic receptors in living neural circuits. Bats and colleagues (Bats, Groc, and Choquet, Neuron 53, 719, 2007) used quantum dots to track the ins and outs of glutamate receptors at synapses, showing that the receptors bring company as they diffuse in the synapse to become trapped via their partner's local connections. Their study sheds new light on the mechanisms used by synapses to change their efficacy, which may impact on our understanding of the cellular and molecular basis of learning and memory.