1202 GMT November 19, 2019
New technologies have fueled the quest to map all the neural connections in the brain to understand how these networks processes information and control behavior, scifeeds.com said.
Mark Alkema, an associate professor of neurobiology at UMass Medical School turned to the nematode C. elegans to find answers. A tiny worm with only 302 neurons, it is the only animal for which its neural road map has been completely defined.
In this study, Alkema and colleagues sought to determine if flipping the sign of a synapse from inhibitory to excitatory in the worm's brain was enough to reverse a behavior. To do this, they analyzed nematode touch response which C. elegans employ to escape from carnivorous fungi that use hyphal nooses to catch nematodes. During this response neurotransmitters are released that activate an inhibitory ion channel. This causes the worm to relax its head and quickly reverse direction away from the predator.
The researchers replaced the inhibitory ion channel with an excitatory version of the channel in a live nematode.
"Surprisingly, the engineered channel does not affect development of and is properly incorporated into the neural circuits of the worm brain," said Alkema. "Cells that are normally inhibited in the brain now get activated.
"What was most striking is that we were able to completely reverse behavior by simply switching the sign of a synapse in the neural network," explained Alkema. "Now the animal contracts its head and tends to move forward in response to touch. This suggests that the neural wiring diagram is remarkably stable and allows these types of changes.
"Our studies indicate that switching the sign of a synapse not only provides a novel synthetic mechanism to flip behavioral output but could even be an evolutionary mechanism to change behavior," said Alkema.