The insular cortex treats pain and gives lessons to the brain
Acute pain, for example, when you hit your leg against a sharp object, is an uncomfortable feeling. Thanks to her, we learn to avoid situations that can be dangerous. This phenomenon called learning by fear helps animals and humans to survive. But which part of the brain warns other areas of painful events for this learning to take place?
We have known for some time that an area of the brain called amygdala plays an important role in learning through fear. Scientists at Ralf Schneggenburger's laboratory at EPFL today discovered that the transmitter of these "warnings" was the insular cortex. Located at the bottom of the lateral groove of the brain, this part of the brain is associated with the coding of the sensations of our body. Moreover, the neurons of the insular cortex are related to those of the amygdala, but the function of this cerebral connection had been little studied before.
As the insular cortex of mice is similar to that of humans, scientists have done their research on rodents. They have engineered light-activated ion channels into specific brain neurons in mice. This allowed them to stop the electrical activity of neurons in the insular cortex by sending short pulses of laser light during the event involving learning by fear.
The researchers found that the mice were almost no longer afraid of a slight electric shock to their paws when they deactivated the insular cortex during the painful situation. In addition, the ability of mice to learn from the painful event has been greatly reduced.
The study demonstrates that, in addition to informing our brain of physical pain, the insular cortex can send a strong signal to other brain regions involved in forming the memory of the unpleasant event. "Since deactivation of the insular cortex suppresses the unpleasant sensation usually associated with the pain event, our study suggests that neurons in this area are responsible for this subjective sensation and induce a learning process in other areas of the body. brain, "explains Ralf Schneggenburger.
