How from birth do we perceive the passage of time? A team from the Lyon Neuroscience Research Center has looked into the subject in newborn rats. We know that in adults, it is the stratium, a cerebral structure, which is strongly involved in the notion of time. But how does it happen at birth?
To find out, the researchers put the pups through a two-week experiment in the lab. An odor was sent for 20 seconds followed by a small electric shock to a first group of pups. In the second group, a shock was sent regardless of the smell. The repetition of these actions made it possible to measure the immobility and their breathing rate of the animals, two characteristics of fear.
As a result, the animals accustomed to receiving the blow just after the smell managed to anticipate and be “afraid of the smell”, particularly when the shock approached, unlike the others. In other words, the first rats learned to perceive the notion of the time that elapsed between the smell and the shock.
Alternative brain circuits to find
It remains to be seen how this materializes at the level of the brain and in particular within the striatum in these animals. And there surprise. This does not occur during the experiment, contrary to what occurs in adult rats. The striatum is still too immature to function in pups. “This result (…) suggests that there are alternative structures allowing the implementation of the representation of time from an early stage”, explains Anne-Marie Mouly, co-author of the work, quoted by inserm. So what part of the brain is mobilized to perceive time? “The amygdala or even the olfactory cortex, (…) already mature at this age, could for example be involved”.
Research will continue to identify precisely the nature of these alternative brain circuits. Ultimately, neuroscientists could then understand the cognitive distortions observed in certain diseases, such as Parkinson disease or the one by Huntington.
