Unlike the precise ticking of mechanical and digital clocks, our brains maintain a decentralized and flexible sense of time, thought to be shaped by the dynamics of neural networks spread across the brain.

Stone in a lake How do our brains perceive time?

In this “internal clock” hypothesis, our brains keep time by relying on consistent patterns of activity that develop in groups of neurons during behavior.

Joe Patton, the study’s senior author, likens this to throwing a stone into a lake: “Every time a stone is thrown into a lake, ripples form outward on the surface in a repeatable pattern. By examining the patterns and locations of these ripples, one can infer When and where was the stone dropped into the water?

Just as the speed at which ripples move can vary, the pace at which these patterns of activity progress in neural populations can also change. “Our lab was one of the first to show a close connection between how quickly or slowly these neural ‘spikes’ develop and time-dependent decisions,” Patton says.

Distinguish between different time periods

In the new study; The researchers trained mice to distinguish between different time periods. They found that activity in the striatum, a deep brain area, follows predictable patterns, changing at different speeds.

This means that neural activity within the striatum is linked to the perception of time, as the observed patterns indicate that the rate at which activity develops in that brain region is related to how the mice subjectively experience the passage of time.

Brain manipulation

But scientists are well aware of the famous rule in science which states that correlation does not equal causation. So; The researchers manipulated the brains of mice.

Researchers say that manipulating neural activity to change perception and perception of time is crucial for several reasons:

By artificially slowing or speeding up patterns of neural activity, researchers can gain insights into how the brain’s internal timing mechanisms work. This research provides causal evidence for the brain’s involvement in time perception and processing.

To determine causality, the team turned to an old-school technique that all neuroscientists know: temperature.

In previous studies; Scientists use temperature to manipulate the temporal dynamics of behaviors. Cooling a particular area of ​​the brain slows down behavior, while heating it speeds it up without changing its structure.

It’s akin to changing the tempo of a piece of music without affecting the notes themselves, the researchers say: “We thought the temperature could be ideal because it would likely allow us to change the speed of neural dynamics without disrupting their pattern.”

To test this tool on mice, they developed a thermoelectric device intended to warm or cool the striatum located deep in the brain; While recording neural activity at the same time.

In these experiments, mice were anesthetized, so the researchers used optogenetics; It is a technique that uses light to stimulate specific cells – creating waves of activity in the striatum.

The researchers found that cooling the striatum actually led to an expansion of the activity pattern, while heating it led to a contraction of activity, without disturbing the pattern of the brain waves themselves.

In other words; The researchers were able to manipulate mice’s perception of time by heating or cooling areas of the brain.

This does not just mean that there is a neural basis for time perception; It also means that it can be manipulated and controlled in external ways.

Causal relationship

Manipulating neural activity allowed researchers to establish causal relationships between brain activity, behavior, and perception of time; By demonstrating that changing neural activity can distort mice’s judgment of time duration, researchers can now establish a direct link between specific neural processes and time perception.

This study also confirms – experimentally and systematically – the validity of the term individual experience of the passage of time, which scientists and philosophers have long talked about.

Time can seem to fly

When we engage in a fun activity, time can seem to fly by. In contrast, when we are bored or engaged in a monotonous task, time may seem to drag on; Our emotional state can also affect our perception of time. In intense or emotionally charged situations, time may seem to slow down or speed up.

For example, during moments of fear or excitement, time may seem to pass more slowly. The study says that subjective perception of time has a neural basis.