Essentials: The Biology of Aggression, Mating & Arousal | Dr. David Anderson

Dr. David Anderson provides a comprehensive overview of the neurobiology underlying emotional states and behaviors. He begins by defining emotions as internal states that control behavior, distinguishing them from simple feelings and emphasizing their neurobiological rather than psychological nature. Anderson explains that emotional states have key properties like persistence (outlasting triggering stimuli) and generalization (applying across different contexts).

A significant portion focuses on aggression research, particularly work on the ventromedial hypothalamus (VMH). Anderson describes two types of aggression identified by Nobel laureate Walter Hess: defensive rage and predatory aggression. His lab's work using optogenetics revealed that offensive aggression in male mice is actually rewarding - they will work to get opportunities to fight. Surprisingly, the neurons controlling aggression are located very close to fear neurons in the VMH, with fear being able to shut down offensive aggression.

Anderson challenges common misconceptions about hormones, explaining that aggression neurons are marked by estrogen receptors, not testosterone receptors. Testosterone's effects on aggression are largely mediated through its conversion to estrogen via aromatization. In females, aggression only occurs during the maternal period when nursing pups, and distinct neural populations control mating versus fighting behaviors.

The discussion covers the role of tachykinins, neuropeptides that increase dramatically during social isolation and promote aggression, fear, and anxiety. Anderson describes promising research showing that drugs blocking tachykinin receptors can reverse the effects of social isolation in mice. Finally, he addresses the brain-body connection in emotions, explaining how the vagus nerve creates bidirectional communication between the brain and organs, contributing to the somatic experience of emotions.