Do you ever have the feeling that you correctly predicted something a few instants before it happened? It is not a superpower but a skill that allows humans to be more successful in navigating the world. Researchers from the University of California, Berkeley have looked at how this happens and discovered that the brain has two timekeeping mechanisms for making short-term predictions.
One of the mechanisms, known as interval timing, relies on past experiences and is connected to the brain's cerebellum. The other one relies on rhythm and is connected to the basal ganglia. Both the cerebellum and the basal ganglia are important regions of the brain linked to movement and cognition. The findings are reported in the Proceedings of the National Academy of Sciences.
“Whether it’s sports, music, speech or even allocating attention, our study suggests that timing is not a unified process, but that there are two distinct ways in which we make temporal predictions and these depend on different parts of the brain,” lead author Assaf Breska, a postdoctoral researcher in neuroscience at UC Berkeley, said in a statement.
The team reached these conclusions by studying how Parkinson’s patients and people suffering from cerebellar degeneration dealt with temporal cues and stimuli. They had to predict when a green flashing square would appear while watching sequences of green, red, and white squares on a screen. One sequence had a steady rhythm and the other had a more complex pattern. Parkinson’s patients were much better at the complex pattern one, while cerebellar degeneration patients were good at the rhythmic one.
“We show that patients with cerebellar degeneration are impaired in using non-rhythmic temporal cues while patients with basal ganglia degeneration associated with Parkinson’s disease are impaired in using rhythmic cues,” senior author Richard Ivry commented.
These results could be very useful for helping sufferers of both conditions. Environments and environmental cues could be modified to make life easier for people with Parkinson’s or cerebellar degeneration. The study provides convincing evidence that humans have at least two internal timing mechanisms, challenging previous theories.
“Our results suggest at least two different ways in which the brain has evolved to anticipate the future,” explained Breska. “A rhythm-based system is sensitive to periodic events in the world such as is inherent in speech and music. And an interval system provides a more general anticipatory ability, sensitive to temporal regularities even in the absence of a rhythmic signal.”