So mice are often found to be pretty chill, to eat what they find and to be generally not that aggressive. However, firing a laser at it’s amygdala makes it go psycho…
Ivan de Araujo, a neurobiologist at Yale University came across a study done in 2005, stating that the amygdala was active during hunting and feeding in rats. This was found to be odd, as the amygdala research is mainly focused on defensive or submissive emotions.
After more research, a sort of switch was discovers in a mice’s amygdala, which when activated, switches on their predatory instinct. In the past, researchers used a technique called optogenetics to alter memories and make mice thirsty. De Araujo used this technique when working with the mice.
Predatory behaviours such as grabbing and biting are familiar to all, but the brain circuits necessary for this to take place are unknown. We know that the central amygdala produces fear and it is activated when hunting. The researchers wanted to know if they amygdala was responsible for these behaviours.
Researches injected the mice with a virus that made their brains sensitive to blue light. Then, they used a tiny optic fibre to shine a blue laser onto its amygdala. This prompted the animal to tense its neck and jaw muscles, and this behaviour didn’t occur when other ares in the brain were stimulated.
When the laser was switched on, the mice hunted everything in their path, from crickets to bottle caps, and even hunted when nothing was present. The researchers thought that “maybe it is jut generalised aggression, or maybe we made them very hungry”. To see if this was true, or to see if the behaviour was actually caused by the light stimulation, they did further tests.
Further tests concluded that there are two pathways in the amygdala that work in tandem to execute a hunt;
- The first controls prey pursuit (PAG)
- The second controls bite accuracy (PCRt)
Targeting PAG with a laser made the mouth either move faster or slower, and targeting the PCRt made the mice’s bite stronger or weaker. When both were stimulate, the mouse stopped whatever it was doing and hunted anything it could find, and proceeded to give a lethal bite.
The mice, however, are able to tell the difference between friend and foe, as when other mice were there, it was curious but made no attacks. This proves that predation is a complex behaviour and the amygdala is involved. It suggests also that because the mice didn’t just attack everything in sight, that other parts of the brain are involved,, helping the amygdala to stay ‘in check’.
Here is a video of the mice’s behaviours;
Where from here?
Maybe this neuron activation can be used to make an army of lethal human killing machines ready for the next war, or maybe we can just defeat enemies with our psycho rats.
I think that whatever science decides to do with this discovery, that we know the brain gets more and more complex the further we delve in.
As Aristotle said;
“The more you know, the more you realise how little you know.”
psychomashup 