Portuguese scientists have identified brain structures responsible for stress reaction in rats in that moment, when she hears that her relatives had ceased to make noise. For this they used the techniques of optogenetics and pharmacological inhibition of neurons: rats individually disconnected amygdala, the average geniculate nucleus of the thalamus and the ventral part of the temporal cortex, did not show a stress reaction to the sudden silence — unlike their counterparts in the control group. How this system works, yet to be explored, write the scientists in the journal PLoS Biology.
Animals to protect themselves from predators, you have to be very careful and carefully monitor the appearance of signals that can mean danger. Such signals can be the noise of leaves, the bright spot in the grass or running in all directions relatives. But for some types, who are guided by rumor, a signal of danger can be the lack of any signal at all. A few years ago scientists led by Ana Pereira (Pereira Ana) from the Center Champalimaud in Lisbon foundthat rats as a signal of danger from neighbors use sharply the silence: for them, it means that another animal was paralyzed with fear.
In the new work, the researchers decided to determine the neural mechanism for this reaction is responsible. In their experiment, took part 22 rats in the first day, uncontrolled was shocked, to cause them stress. The next day they individually ran into the cage where they could move freely. At this time, they included the sounds of the movements of other rats, and then abruptly turned off and monitor whether the rats to be afraid and to stand still.
Seven rats in the neurons of the amygdala (area of the brain responsible for processing negative emotional stimuli) introduced the inhibitory archirodon (ArchT), which can optogenetics to activate the green light. These rats did not react to the cessation of noise from other rats and stood in contrast to the rats from the control group, those who did not enter ArchT.