Learning and memory are processes that link experience with behavior and therefore play central roles in our daily experience. That there exists a physical basis for these processes seems at first hard to imagine - except for the fact that physical disruptions in the brain, such as stroke or disease, can make them go wrong.
This week, researchers report that by making targeted genetic disruptions that disable a key neurotransmitter receptor in the fruit fly, they have uncovered an important clue to the physiological mechanisms at work in learning and memory.
The subject of the study was the so-called NMDA receptor - a neurotransmitter receptor possessing special properties that could make it especially useful in learning and memory. In particular, past work has shown that NMDA receptors can respond in a special way to concurrent events on both sides of a synapse. Acting in this way as "coincidence detectors," NMDA receptors may help neurons form stronger or weaker connections with each other depending on whether they are repeatedly stimulated together. Neuroscientists strongly suspect that this process - called synaptic plasticity - of modulating the strength of synaptic connections on the basis of experience forms an elemental, neuron-level basis for learning and memory.