The same neurotransmitter involved in infatuation and reward advances or delays the internal clock depending on our expectations
When we expect something raring a tryst, for example, time seems to tediously slow. And when the desired situation comes, they spend hours in a sigh. Something similar happens with the perception of time as we grow: in childhood clock seems very slow but compliments fifty accelerates . Why the estimation of time changes with the situation, the stage of life or even in some pathologies such as Parkinson?
All these examples point in the same direction, as reflected in research published in the journal “Science ” , pointing responsible to dopamine , the neurotransmitter involved in love, reward, motivation and movement , among other functions. The idea is not new.
The old hypothesis of “clock dopamine” left in the hands of this substance the measure of “subjective” or psychological time , as it is estimated for a wait. The ability to accurately measure these periods depends on factors such as motivation, attention and emotions, as illustrated by the previous examples.
However, unlike vision or hearing, the trial on time is not linked to any organ of the senses. But his estimate is crucial for survival in all species. From an animal that forages in open at the mercy of predators, our life in the city, to decide or not to cross a road at the approach of a vehicle ground.
It was suspected that the neurons that produce dopamine, located in the midbrain, had an important role as regulators of this internal clock, but needed to find the direct link between those neurons signals and transmitted over time . To fill that gap, neuroscientists Champalimaud Center for the Unknown (Lisbon) looked the activity of these neurons in mice trained to calculate whether an interval between two acoustic signals was shorter or longer than a second and a half. Oddly enough, after months of training, the mice were very competent to estimate it .
In parallel, the activity of dopaminergic neurons was measured and found that transient inhibition or activation could slow down or accelerate the time estimate. If stimulated to produce more dopamine, mice tended to underestimate the time , and if shuttered, tended to overestimate it . “This, together with naturally occurring signals observed in the previous experiment shows that the activity of these neurons is sufficient to alter the perception of time,” the researchers explain.
Can we extrapolate this result to humans? It is possible, but the problem, researchers say, is that observed in mice “can not be said to be a perception, since animals can not express what they felt.” However, they point to two facts that could corroborate . The first, “the ability of young lovers , with his brain flooded with dopamine, to stay up all night talking, not noticing the passage of time.” And the second, more scientific, the estimated time much slower in people with Parkinson ‘s , a disease in which there is a deficit of dopamine precisely.