In a paper published in the November 30 issue of the journal Cell, researchers from UCSD's Divisions of Biology and Physical Sciences describe their achievement, a "Holy Grail" for neuroscientists who have long sought concrete evidence for how nerve connections in the brain are changed temporarily and permanently by our experiences.
"The long-term memories stored in our brain last our entire lives, so everybody had assumed that there must be lasting structural changes between neurons in the brain," says Michael A. Colicos, a postdoctoral fellow at UCSD and the lead author of the paper. "Although there's been a lot of suggestive evidence to indicate that this is the case, it's never before been directly observed."
"While most people assumed that some sort of rearrangement of nerve cell connections took place in the brain, this was extremely difficult to demonstrate experimentally," says Yukiko Goda, a professor of biology at UCSD who headed the research team, which included Michael J. Sailor, a professor of chemistry and biochemistry at UCSD, and Boyce E. Collins, a postdoctoral fellow in Sailor's lab. "Some investigators saw increases in the number of synapses in the brain in response to stimuli, while others saw no changes. There are a billion synapses in a cubic centimeter of brain tissue, so no one could tell for certain whether the statistical comparisons of synapse density between one sample and another showed a real increase."
To resolve this problem, the UCSD researchers focused their attention on individual nerve cells, specifically neurons from the hippocampus-the
Contact: Kim McDonald
University of California - San Diego