Nagoya researchers identify orexin neurons as key drivers of sustained motivation

Researchers at Nagoya University's Graduate School of Medicine discovered that orexin neurons play a pivotal role in maintaining motivated behavior. By engineering orexin-Cre rats, they could precisely manipulate these cells and observe changes in a progressive-ratio food-reward test. Activation of orexin neurons raised the breakpoint, indicating greater willingness to work, whereas targeted degeneration lowered it.

Fiber-optic recordings showed that orexin activity spikes during reward expectation and stays elevated when the reward fails to appear, intensifying with increased effort. Optogenetic inhibition at the moment of expectation reduced task performance, while additional excitation did not further enhance motivation, suggesting a necessary but not limitless role for orexin. The findings, published in PNAS, may help explain motivational deficits seen in depression, addiction and ADHD and point to new therapeutic targets.