How the brain measures time
Washington: In a new study, researchers have found a small population of neurons that is involved in measuring time, which is a process that has traditionally been difficult to study in the lab.
In the study, researchers at the University of Minnesota’s Center for Magnetic Resonance Research (CMRR) developed a task in which monkeys could only rely on their internal sense of the passage of time. Their task design eliminated all external cues which could have served as “clocks.”
The monkeys were trained to move their eyes consistently at regular time intervals without any external cues or immediate expectation of reward.
The researchers found that despite the lack of sensory information, the monkeys were remarkably precise and consistent in their timed behaviours.
This consistency could be explained by activity in a specific region of the brain called the lateral intraparietal area (LIP).
Interestingly, the researchers found that LIP activity during their task was different from activity in previous studies that had failed to eliminate external cues or expectation of reward.
“In contrast to previous studies that observed a build-up of activity associated with the passage of time, we found that LIP activity decreased at a constant rate between timed movements,” lead researcher Geoffrey Ghose said.
“Importantly, the animals’ timing varied after these neurons were more, or less, active. It’s as if the activity of these neurons was serving as an internal hourglass,” he said.
By developing a model to help explain the differences in timing signals they see relative to previous studies, their study also suggests that there is no “central clock” in the brain that is relied upon for all tasks involving timing.
Instead, it appears as though each of the brain’s circuits responsible for different actions are capable of independently producing an accurate timing signal.
The study has been published in the journal PLOS Biology.