In theory, the behaviour of animals has often been reduced to particular circuitry in the brain. Likewise, the amygdala, which can literally be defined as an ‘almond’ shaped region within the brain, has often been linked with predatory behaviours and its associated emotional and motivational outcomes in several animals.

Now using the cutting-edge technique of optogenetics, it seems the researchers from Yale University have managed to successfully control predatory behaviour in mice via a switch in the form of two distinct sets of neurons in the amygdala. This technique involved inducing these particular neurons to activate using a laser light, and so can be used to control the activation by turning the light on and off.

On January 12, the study published its results in the scientific journal Cell, identifying the neurons in the central nucleus of the amygdala that respectively control the motor actions of hunting, like running and speed, along with the other region coordinating the neck and jaw muscles critical for the biting in mice.

Lead author Dr Ivan de Araujo, a psychiatric researcher at the School of Medicine at Yale explains how the turning on the target neurons, lead to the rodents to mindlessly pursue and aggressively attack any object in their line of sight, including conventional and artificial preys like insects to even everyday objects such as bottle caps and wooden sticks. However, this effect was limited to stimuli that were a smaller than the size of mice themselves and therefore they did not feel compelled to attack other mice or the handlers.

Moreover, these two areas controlling pursuit and biting of prey were also functional independently, whilst the level of hunger the rodents displayed was a significant factor in the level of aggression displayed during the pursuit.

This has resulted in Dr Araujo to conclude that perhaps this circuitry is more critical in the primal motivation and drive to find food as oppose to more aggressive behavioural responses.

“My take on this is that predatory behaviour is more related to food intake itself,” he stated. He further concludes “I would be a little hesitant to associate this with aggression.”

The study carries implications in understanding the evolutionary role of the amygdala in aiding jawed predatory animals, like humans, to efficiently catch their prey and allow them to settle at the top of the food chain.

Palwasha Najeeb, Correspondent (Science)

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