🧠 Our brain deceives us: it alters what our eyes see

Contrary to what is often believed, our vision does not passively capture the world like a camera. Neuroscientists have discovered that what animals see is in reality constantly transformed by their actions and by what they feel.

The prefrontal cortex, a brain region essential for decision-making, is at the heart of this process. An MIT study, published in Neuron, shows that this area sends tailored signals to the parts of the brain dedicated to vision and movement. These signals are adjusted instantaneously based on the animal's activity, such as its level of alertness or whether it is moving, which allows for the constant refinement of perception.


The study focused on two specific areas of the prefrontal cortex: the anterior cingulate area (ACA) and the orbitofrontal cortex (ORB). Each maintains privileged connections with key regions: the vision area (VISp) and the movement area (MOp). For example, when an animal is more awake, the ACA sends signals for the visual area to detect more details. Conversely, the ORB seems to act as a filter, reducing visual activity when alertness becomes very high, likely to avoid an information overload.

To identify these connections, researchers used brain imaging techniques. They placed mice in front of changing images while letting them run on a wheel. Sometimes, a light puff of air altered their level of alertness. Meanwhile, neuron activity was recorded in the four studied brain regions, revealing the exchanges occurring there.

The analysis of the recordings showed that the ACA transmits detailed information about the images, notably contrasts, and is very sensitive to the level of wakefulness. The ORB, on the other hand, only activates at very high levels of alertness. Regarding movement, both areas inform the motor cortex of the speed of movement, but for vision, they simply signal whether the mouse is active or not, which indicates distinct functions.


To verify the role of these circuits, scientists temporarily blocked communication between the ACA/ORB and the visual area. This experiment confirmed that they modulate vision in opposite ways depending on whether the animal is moving or its state of alertness. The brain thus uses these pathways to accentuate or, conversely, set aside certain information, depending on the situation.

These results illustrate an important principle: the prefrontal cortex does not send a single signal to the entire brain. Each sub-region sends specialized messages to specific areas to reshape their activity. This allows the brain to constantly adjust perception and action according to the individual's state, offering new perspectives for understanding functions like attention.