The magic of movies is all the work of a small area of the brain that
transforms individual frames into the illusion of moving images
, without interruptions between one and the other.
Now this fundamental structure has finally been identified in the
superior colliculus
, vital not only for watching a film but above all for the
dynamic perception of the world around us
.
The result is due to a study by the Champalimaud research center in Lisbon published in the journal Nature Communications, which opens new avenues for the understanding and treatment of visual impairments, optic nerve diseases, stroke and autism.
The speed at which flashes of light must follow each other for the brain to perceive them as a steady light rather than a flashing light is known as the '
flicker fusion threshold'
and varies greatly between different animals: for example, birds have a much higher threshold compared to humans, and can therefore also detect extremely fast movements.
However, using different methods to measure this threshold usually results in different results.
To shed some light on the issue, researchers coordinated by Noam Shemesh therefore chose to combine brain scans with functional magnetic resonance imaging, experiments to evaluate behavior and electrical recordings of brain activity.
The goal was to observe the brain when it switches from the perception of single flashes to that of a fixed light and identify the regions involved in this process.
All the data collected by doing experiments with mice pointed to the same area: the superior colliculus.
“At lower light frequencies, each flash seems to be processed by this structure as an important novelty – explains Rita Gil, co-author of the study together with Mafalda Valente – but when the frequency increases beyond a certain threshold, the superior colliculus seems to decide that the stimulus is no longer new or noteworthy and therefore reduces its activity, making it perceived as continuous".
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