It has been said that the volume of the human brain does not increase in adults, but in recent years it has been reported that the volume of the hippocampus and cerebellum changes due to the acquisition of new skills in adults. There is a change.It was also known that the nucleus accumbens of the brain is involved in reward and motivation for skill acquisition.In 2011, the research group succeeded in training marmosets to use tools to feed when they were motivated, and it was said that the sense of accomplishment for the task was related.

　This time, the research team trained four female marmosets for a year, using rake-like tools to feed them in various positions beyond their reach.Taking a magnetic resonance image (MRI) of the brain while training with increasing difficulty step by step.As a result of analysis by a method called digital brain structure image analysis technology (VBM), volume increase of the nucleus accumbens and visual cortex (posterior brain) was observed only during the training period.Changes in the visual cortex are related to visual movement control that moves while looking at the tool, and changes in the nucleus accumbens are associated with activation when the difficult task is achieved because it increased in the latter half of the training when the difficulty of training increased.

　This achievement is significant in that it shows the possibility of advancing the cognitive evolution of primates by creating a neural basis for continuous learning through learning and its success.In the application to humans, it is expected to develop educational methods that are enjoyable by voluntarily tackling studies and tasks, and to develop intervention methods for mental and neurological disorders that show diminished motivation such as depression.