日本名古屋大学研究人员识别出一种名为orexin neurons的脑细胞，在维持动机行为中起关键作用。[1] 该研究由医学研究生院副教授水口浩之和名誉教授山田清文主导，发表于《美国国家科学院院刊》2026年第123卷第27期。[1]
研究人员通过对遗传改造大鼠的实验阐明了这些神经元的功能机制。[1] 当激活orexin neurons时，大鼠在进度比测试中达到更高的断点，表明其为获得奖励愿意投入更多工作；反之，抑制这些神经元的活动则导致大鼠达到的断点更低，动机减弱。[1] 利用纤维光度法监测显示，orexin神经元在预期奖励时活动增加，奖励到达后活动下降，但当预期的奖励未出现时，神经元活动保持在较高水平。[1] 研究人员采用光遗传学技术在大鼠预期奖励时选择性地抑制这些神经元，导致动物表现出更低的动机行为，进一步确认了其活动与动机强度的因果关系。[1]
这一发现可能有助于深化对抑郁症、成瘾和注意力缺陷多动障碍等病症中动机缺失现象的理解。[1]
Researchers at Nagoya University have discovered that specialized brain cells called orexin neurons play a crucial role in sustaining motivated behavior.[1] Led by Associate Professor Hiroyuki Mizoguchi and Professor Emeritus Kiyofumi Yamada from the university's Medical Research Institute, the team conducted experiments on genetically modified rats to understand how these neurons regulate motivation.[1] The findings, published in the Proceedings of the National Academy of Sciences (PNAS) Volume 123, Issue 27, may offer insights into motivation deficits associated with depression, addiction, and ADHD.[1]
In behavioral tests, rats with activated orexin neurons showed significantly higher breakpoints on a progressive ratio test, meaning they were willing to work harder to obtain rewards.[1] Conversely, when orexin neuron activity was suppressed, the animals achieved lower breakpoints and displayed diminished motivation.[1] Using fiber photometry, researchers observed that orexin neuron activity increased when rats anticipated a reward and declined once the reward was delivered; when anticipated rewards failed to materialize, the neurons maintained elevated activity levels.[1] Further experiments employing optogenetics—a technique that uses light to control neural activity—revealed that suppressing orexin neurons specifically during reward anticipation caused animals to exhibit reduced motivated behavior.[1]