Brain signals thought to predict events may instead track time

Neuroscientists have long believed that certain brain signals predict upcoming events. This idea has been a key part of neuroscience, as it helps explain how the brain builds internal models to learn and anticipate what comes next. However, a new study challenges this long-held interpretation. Instead of being predictive signals, these neural ramps may simply be the brain tracking the passage of time.

Farzaneh Najafi, an assistant professor at Georgia Tech's Institute for Neuroscience, says the findings could change our understanding of how the brain represents time. The team designed experiments with mice to test if the neural ramps were indeed predicting events. They presented the mice with both predictable and unpredictable stimuli, hoping to see a difference in neural activity. However, the results showed that even when the events were predictable, the neural activity remained largely the same.

The study found that the neural ramps were present even in naive mice, which had never seen the stimuli before. This suggests that these signals are not related to predicting future events, but rather to encoding the time that has elapsed. The researchers propose that the brain might be using these signals to "relax" from the past, rather than building up anticipation for future events.

This finding challenges the notion that there are specialized areas in the brain dedicated to time tracking. Instead, it suggests that timing may emerge from the intrinsic properties of neurons themselves. The study opens up new questions about when and where these signals might emerge in the brain, and whether they can be detected in more complex tasks or in different brain regions.