A research team from National Tsing Hua University (NTHU) has mapped the neural pathways that mediate between external sensory signals and the behavior in a fruit fly’s brain, which could bring researchers closer to understanding how the human brain is wired.
Funded by the National Science Council, the research team led by Chiang Ann-shyn (江安世), a professor of life sciences and director of NTHU’s Brain Research Center, said that although the human brain has more than 100 billion neurons, while a fruit fly’s has only about 100,000, they share similar basic behaviors and gene regulation mechanisms, so understanding the functions of a fruit fly’s brain can provide clues to that of a human.
Using fruit flies, which can sense carbon dioxide, the team discovered that contrary to previous assumptions that sensory signals are transmitted through a single neural pathway, they found that three parallel neural pathways activate when a fly senses carbon dioxide, and also mapped the functions of these pathways.
“When a fly senses a lower concentration of carbon dioxide, it only activates the first pathway that leads it to perform an avoidance behavior. But if it senses a higher concentration of carbon dioxide, all three pathways are activated, with the third pathway repressing the first, causing the signal to go via the second pathway,” said Lin Hui-hao (林暉皓), a team member and lead author of a research paper on the study published in Science magazine this month.
Giving the example of railway trains switching tracks, Chiang said they found that the third pathway serves as a “shunting” mechanism mediating signals and responses in the fly’s neural pathways.
Chiang said that if researchers can determine whether the mechanisms work the same on the fly’s other senses, and if human brains operate in the same way, the discoveries could help decode mechanisms in the human brain and prevent or cure diseases such as Alzheimer’s, Parkinson’s or Huntington’s.