Light-reward study points to a brain route for learning new skills
University of Otago researchers say a rodent study shows how a visual cue can gain reward value and help train future actions.
By Priya Raghavan · Science Reporter
3 min read
A flash of light paired with a reward changed how rodents' brains processed that visual signal, according to a University of Otago-led study. The finding matters because it identifies a cellular route by which a neutral cue can become meaningful during learning.
The study, led by University of Otago—Ōtākou Whakaihu Waka researchers and published in Nature Communications, examined a modern version of classical conditioning. Instead of pairing a bell with food, as Ivan Pavlov did in his 1890s experiments with dogs, the researchers paired a light flash with a reward in rodents.
How a cue becomes meaningful
According to the University of Otago, the work showed how a stimulus with no built-in reward value can acquire positive significance after repeated pairing with something rewarding. Professor John Reynolds, the study's lead author from the university's Department of Anatomy, said the brain looks for links between actions, cues and valuable outcomes so useful patterns can become habits.
Reynolds said the researchers saw the visual response strengthen in the superior colliculus, a sensory brain region involved in early visual processing. According to the university, that stronger response persisted unless the light was repeatedly shown without the reward.
The researchers reported that dopamine and serotonin were both needed for the strengthening process in the superior colliculus. Dopamine is closely tied to reward learning, while serotonin is among the major neurochemicals involved in brain signaling.
Once the visual signal had strengthened, Reynolds said, it began passing through the superior colliculus in a way that directly promoted dopamine release in areas involved in learning reward-seeking actions. The University of Otago said that finding connects the learned value of the light cue with the brain systems that help animals learn what to do to obtain a reward.
A link between two kinds of learning
The study addresses two forms of learning commonly discussed in neuroscience. Classical conditioning involves learning that one event predicts another, such as a cue predicting a reward. Operant conditioning involves learning that a particular action can produce a reward.
According to Reynolds, the new work suggests the reward value formed through classical conditioning can feed into later action learning. The university said the study is believed to be the first report of a cellular mechanism directly connecting classical and operant conditioning.
Reynolds said scientists still do not fully understand the neural mechanisms behind sensory conditioning by reward, despite more than a century of research after Pavlov's experiments. He said the new result was notable because the effect was found in the superior colliculus, an older visual brain structure, rather than being centered in the cerebral cortex.
The paper, titled “The superior colliculus gates dopamine responses to conditioned stimuli in visual classical conditioning,” lists Yan-Feng Zhang and colleagues as authors. It was published in Nature Communications with the DOI 10.1038/s41467-026-72167-4.
This story draws on original reporting from Medical Xpress.