Professor Katsuo Tokunaga of the Graduate School of Life and Environmental Sciences, University of Tsukuba, and Takatoshi Honda, a graduate student and a research fellow of the Japan Society for the Promotion of Science (DC1), created a transgenic Drosophila and directly connected the neural circuit with light and heat. By activating, we succeeded in artificially forming reward memory in the brain of a living individual.We elucidated the neural circuit mechanism in the brain that learns by associating different information.
In "federated learning," known as Pavlov's dog, animals associate external stimuli that cause learning behavior (conditional stimuli) with stimuli that cause innate reactions (unconditional stimuli), and conditions are based on their memories. It becomes possible to predict the existence of unconditional stimuli from stimuli.Although such classical conditioning has been widely reported in the animal kingdom, a comprehensive understanding of the neural circuits on which associative learning behavior is woven has not been achieved so far.
Therefore, in this research, by combining cutting-edge technologies called optogenetics and thermogenetics, the neural circuit that conveys odor is light, and the neural circuit that conveys reward is heat. Create a genetically modified Drosophila that can be manipulated by.Using the larva as a model, we attempted to identify the neural circuit that supports associative learning behavior.
As a result of the demonstration, it was found that when the genetically modified larvae created were given physical stimuli such as light and heat to activate the neural circuit at the same time, associative memory was artificially formed.This is the result of experimentally showing that the neural circuit of associative memory, which has been theoretically proposed so far, actually functions in the brain of a living individual.
In this study, we succeeded in identifying the smallest functional neural circuit unit that supports associative learning, and the nerves that control the higher-order behavior "learning and memory" that is conserved across organisms, from insects to humans. It is expected as a new technology that can approach the circuit at the single nerve cell level.
In addition, since this experimental method directly activates neural circuits, the time required for conditioning has been significantly reduced, and the conventional behavioral experiment system has been dramatically improved.It is considered that such a method can be applied to behavioral analysis of risk genes, etc., which are presumed to cause impaired learning and memory function, and efficient drug screening.
