NEURAL MECHANISM UNDERLYING MOTIVATION TO APPROACH HUMANS IN MICE SHOWING ACTIVE TAMENESS

Neural circuits dictating anxiety, social behaviour, and fear responses are essential for an animal’s survival. These behaviours are observed to be affected during the domestication process. A hallmark of domesticated animals is their tendency to voluntarily approach and interact with humans. This behaviour is known as active tameness. My study aimed to explore the neurobehavioral basis of active tameness gained during domestication.
In this study, I use wild-derived heterogeneous stock (WHS) mice selectively bred to show active tameness. To examine the effects of selective breeding, WHS mice were subjected to a battery of tests designed to explore various aspects of their behaviour. Selective pressure for active tameness significantly influenced social behaviour. Tame mice exhibited heightened sociability and a strong preference for non-aggressive interactions even in stressful social situations. Their territorial aggression, however, was conserved. These behavioural changes did not show any sex-specific effect. Notably, other traits such as exploratory behaviour, anxiety, or preference for novel stimuli were unaffected.
Neural network driving active tameness was mapped using c-Fos, an early gene marker of neuronal activation. I observed reduced activity in the dorsal premamillary nucleus (PMd), dorsomedial hypothalamus (DMH), and ventromedial hypothalamus (VMH) of tame mice, regions typically activated during threat responses. This decreased activation suggests that an altered threat circuit may be a central mechanism enabling tameness.