A Taiwan-based research team has made a major breakthrough in the understanding of brain function by identifying two neurons in charge of long-term memory formation in the fruit fly.
“The fruit fly brain, with about 100,000 neurons, is far less complicated than the human brain, which has about 100 billion neurons, but their general structures are similar, as are memory and learning behaviors,” said team leader Chiang Ann-shyn, a professor of life sciences and director of National Tsing Hua University’s Brain Research Center, at a Feb. 13 news conference at the National Science Council.
“Thus we can use the fruit fly brain, and behavior, to help us understand our own brain and how it forms long-term memories.”
Having spent the past seven years compiling high-resolution 3-D images of fruit fly brains, Chiang and his colleagues searched the brains for neurons involved in long-term memory formation, using a temperature-sensitive toxin they developed that blocks protein synthesis, as earlier research showed that long-term memory depends on the production of new proteins.
They found that turning off protein synthesis in two specific neurons, the dorsal-anterior-lateral neurons, stopped the fruit flies from developing new long-term memories.
This finding came as a surprise, Chiang said, as the DAL neurons are located outside the mushroom body, or corpora pendunculata, the part of the insect brain where long-term memory formation was previously believed to take place.
When the team inhibited protein synthesis in the mushroom body, however, the flies still formed long-term memories, indicating that the DAL neurons are the crucial site.
Further work using colored proteins showed that two genes—calcium/calmodulin-dependent protein kinase II and period genes—in the DAL neurons are responsible for the necessary new protein synthesis, he added.
Better understanding of how specific neurons, genes and proteins function in long-term memory could help scientists in search of new drugs for neurodegenerative diseases such as Alzheimer’s and Parkinson’s, Chiang said.
The results of the team’s research have been published in the latest issue of the journal Science. (THN)
Write to Kwangyin Liu at kwangyin.liu@mail.gio.gov.tw