Recent advances in high-resolution microscopy and image analysis have made it possible for researchers to "look under the hood of the molecular engine," to view nerve cells and the interaction among components of their basic cytoskeletal structures and among nerve cells in general. Study of the images has led to some unexpected findings, particularly regarding the adult brain, according to Shelley Halpain, associate professor in the Department of Cell Biology at The Scripps Research Institute in La Jolla, CA.
"We have found that the synapses themselves are motile and undergo metamorphoses that we consider to be very surprising in a mature person," Halpain said. "The idea that the mature brain is plastic is quite new. If we could find out more about this capacity for restructuring and reorganization, we could probably harness that information to promote recovery from diseases that involve synaptic abnormalities." Halpain added that the brain cells of children and young adults are considerably more active than those of older adults.
Neurons-the brain has billions of them-first migrate from their place of birth to appropriate locations within the brain. Each neuron then grows a long axon, which transmits messages from the neuron to other nerve cells, using chemical messengers called neurotransmitters. Dendrites, which also extend out from the new neuron, are charged with bringing messages to the neuron from other nerve cells. The tentacle-like axons and dendrites form synapses with other axons and dendrites, eventually "wiring up" the brain.
Halpain and two colleagues will discuss the role of "motility," or movement, in the development of neurons, as well as the way in which the nerve cells' "signaling machiner