Scientists Identify Orexin Neurons That Help Rats Stay Motivated

Motivation - or its absence - influences our daily lives in both major and minor ways. Whether we are switching careers or simply changing television channels, our choices are shaped by what drives us and by the rewards we value.

A new study in PNAS, led by researchers at Nagoya University in Japan, has found that neurons producing the chemical orexin play a key part in rats’ motivation to obtain food rewards.

These cells sit in the brain’s hypothalamus. Earlier research has associated them with wakefulness, energy use and, indeed, motivation. The team behind the new work set out to examine that motivational connection more closely.

"A potential mechanism for translating expectations into sustained action."

– Neuroscientist Hiroyuki Mizoguchi

Orexin neurons and food-reward motivation

The experiments revealed orexin’s moment-by-moment influence, showing how closely it is involved in judging whether a potential reward justifies the effort needed to earn it - a central calculation in motivation.

Watch the study video on YouTube.

"Our observations highlight that orexin activities are implicated in the motivational process in rats and that dynamic changes in activation of orexin neurons may be involved in reward-seeking behavior based on reward prediction," write the researchers in their published paper.

"In particular, orexin neuron response depends on degree/size of effort; these changes may indicate expectation for incentive against one's efforts."

Using genetic modifications, the researchers could artificially increase or restrict the activity of orexin-producing neurons. During food-reward tests, rats worked harder to obtain food when their orexin neurons were activated, but stopped trying sooner when those neurons were inhibited.

Real-time observations of naturally occurring orexin neuron activity also showed that it rose before rats received a reward, then fell after the reward was delivered. When a reward was anticipated but failed to arrive, orexin activity stayed elevated.

Rats were tested on tasks and rewarded with food. (Dong et al., PNAS, 2026)

The more work the rats had to do for a reward, the greater the activity in these neurons. This indicates that orexin activity could potentially serve as a marker for the effort involved in seeking an expected reward.

"Our study demonstrated significant changes in orexin neuron activity depending on expected rewards and the effort required, suggesting a potential mechanism for translating expectations into sustained action," says neuroscientist Hiroyuki Mizoguchi of Nagoya University.

How orexin activity affects persistence

In additional experiments, the scientists manipulated orexin neuron activity while rewards were expected. Lowering activity appeared to reduce motivation, while raising it did not correspond with greater motivation.

The neurons may therefore be needed to maintain motivation at a particular baseline, rather than functioning precisely like a dial that can simply be turned up or down.

"Therefore, orexin is crucial for linking predicted expectations with motivated behavior," write the researchers. "Moreover, optimization of orexin activity is necessary to overcome difficulties during motivated behaviors."

Naturally, these findings must still be applied to the human brain. However, people also possess an orexin system, making this a significant avenue for future work on committing to a task and remaining committed to it.

Disrupted motivation is associated with several mental health disorders, including depression and addiction. A better understanding of how orexin works in the brain could also help improve treatment for these conditions.

That prospect remains distant. The researchers next plan to investigate the incoming and outgoing brain circuits linked to orexin neurons, to establish the natural sequence of events that switches them on or off.

Related: One Brain Chemical May Be Key to Breaking a Habit, Study Finds

Motivation is such a basic force behind behaviour that any further insight into its workings is likely to have broad implications.

"A better and further understanding of orexinergic mechanisms underlying motivated behaviors would provide insights into the ways that motivation can be developed, and the disorders can be overcome," write the researchers.

The research was published in Proceedings of the National Academy of Sciences.

This article was fact-checked and edited by Rebecca Dyer. Although we take pride in our process, we are only human. If you notice an error, please let us know.